Expansive laminoplasty for myelopathy in ossification of the longitudinal ligament

Risk factors for closure of lamina after open-door laminoplasty

Object

This retrospective study was conducted to evaluate the prevalence and clinical consequences of postoperative lamina closure after open-door laminoplasty and to identify the risk factors.

Methods

Eighty-two consecutive patients with cervical myelopathy who underwent open-door laminoplasty without plates or spacers in the open side (Hirabayashi's original method) were included (62 men and 20 women with a mean age of 62 years and a mean follow-up of 1.8 years). In 67 patients the cause of cervical myelopathy was spondylotic myelopathy, and in 15 it was caused by ossification of posterior longitudinal ligament. Radiographic measurements were made of the anteroposterior diameters of the spinal canal and vertebral bodies from C3–6, and the presence of kyphosis were assessed. Lamina closure was defined as ≥ 10% decrease in the canal-to-body ratio at the final follow-up compared with that immediately after surgery at ≥ 1 vertebral level. The impact of lamina closure on neck pain, patient satisfaction, Japanese Orthopaedic Association scores, and recovery rates were also evaluated.

Results

The mean canal-to-body ratio at C3–6 was 0.69–0.72 preoperatively, 1.25–1.28 immediately after surgery, and 1.18–1.24 at the final follow-up examination. Lamina closure was observed in 34% of patients and was not associated with sex, age, or cause of myelopathy, but was significantly associated with the presence of preoperative kyphosis (p = 0.014). Between patients with and without lamina closure, there was no significant difference in preoperative (9.7 ± 3.1 vs 10.6 ± 2.5) and postoperative (13.7 ± 2.4 vs 13.1 ± 2.7) Japanese Orthopaedic Association scores, recovery rates (53.9 ± 29.9% vs 44.3 ± 29.5%), neck pain scores (3.5 ± 0.7 vs 3.3 ± 1.0), or patient satisfaction level (4.0 ± 1.4 vs 4.8 ± 1.0).

Conclusions

Lamina closure at ≥ 1 vertebral level occurred in 34% of patients. Although patients with lamina closure obtained equivalent recovery from myelopathy in a short-term follow-up, they tended to be less satisfied with surgery compared with those who did not have closure. The only significant risk factor identified was the presence of preoperative cervical kyphosis, and preventative methods for lamina closure, therefore, should be considered for patients with preoperative kyphosis.

Diabetes and smoking as prognostic factors after cervical laminoplasty

We reviewed 87 patients who had undergone expansive cervical laminoplasty between 1999 and 2005. These were divided into two groups: those who had diabetes mellitus and those who did not. There were 31 patients in the diabetes group and 56 in the control group. Although a significant improvement in the Japanese Orthopaedic Association score was seen in both groups, the post-operative recovery rate in the control group was better than that of the diabetic group. The patients’ age and symptom duration adversely affected the rate of recovery in the diabetic group only. Smoking did not affect the outcome in either group. A logistic regression analysis found diabetes and signal changes in the spinal cord on MRI to be significant risk factors for a poor outcome (odds ratio 2.86, 3.02, respectively). Furthermore, the interaction of diabetes with smoking and/or age increased this risk.

We conclude that diabetes mellitus, or the interaction of this with old age, can adversely affect outcome after cervical laminoplasty. However, smoking alone cannot be regarded as a risk factor.

Clinical feasibility of minimally invasive cervical laminoplasty

Minimally invasive approaches to the cervical spine for lateral disc herniation or foraminal stenosis have recently been described. Lower rates of blood loss, decreased narcotic dependence, and less tissue destruction as well as shorter hospital stays are all advantages of utilizing these techniques. These observations can also be realized with a minimal access approach to cervical laminoplasty. Multiple levels of the cervical spine can be treated from a posterior approach with the potential to decrease the incidences of postoperative axial neck pain and kyphotic deformity. In this report the authors present a concise history of the open laminoplasty technique, provide data from previous cadaveric studies (6 cases) along with recent clinical experience for minimally invasive laminoplasty, and describe the advantages and challenges of this novel procedure.

Brachial neuritis: an under-recognized cause of upper extremity paresis after cervical decompression surgery

STUDY DESIGN

Case series.

OBJECTIVE

To identify an alternative etiology for the development of upper extremity weakness after cervical spine surgery.

SUMMARY OF BACKGROUND DATA

The development of proximal upper extremity paresis after cervical decompression surgery is commonly diagnosed as postoperative C5 palsy. Symptoms most commonly consist of weakness involving the deltoid and/or biceps brachii muscles, and in many patients there is also associated pain in the shoulder region with or without sensory deficits. Interestingly, the onset of symptoms is often delayed until days to weeks after surgery. The pathogenic mechanisms underlying postoperative C5 palsy remain unclear, although direct injury to the nerve root during surgery or a traction injury from a tethering phenomenon are frequently cited. These explanations seem unlikely, however, given the delayed onset of symptoms.

METHODS

Two patients who underwent cervical decompression surgery with subsequent development of shoulder pain associated with proximal upper extremity weakness are presented.

RESULTS

Based on clinical presentation and nerve conduction/EMG studies, both patients were diagnosed with brachial neuritis. This article describes an alternative diagnosis for the constellation of symptoms typically attributed to postoperative C5 palsy. Specifically, brachial neuritis is a type of peripheral neuropathy that involves the sudden onset of pain in the shoulder girdle followed by weakness, most commonly of the deltoid and spinati muscles.

CONCLUSION

Brachial neuritis appears to be an under-recognized cause of delayed-onset shoulder pain associated with upper extremity weakness that develops as a consequence of the stress of surgery rather than as a complication of surgical technique.

Open-door Laminoplasty With Suture Anchor Fixation for Cervical Myelopathy in Ossification of the Posterior Longitudinal Ligament

Expansive laminoplasty was developed to achieve posterior spinal cord decompression while preserving cervical spine stability. In the classic Hirabayashi procedure, the lamina door is tethered open by sutures between the spinous process and facet capsule or paravertebral muscle. The authors present a modified technique, which enhances secure fixation and prevents restenosis owing to hinge closure. Twenty-seven patients (7 females, 20 males) with cervical myelopathy secondary to ossification of the posterior longitudinal ligament were enrolled. Each patient underwent unilateral open-door laminoplasty with suture anchor fixation. Tying and fixation of the sutures onto the holed lateral mass screws was used instead of the conventional method. Radiography, magnetic resonance imaging, and computed tomography scanning were used for imaging studies. The Nurick score was used to assess myelopathy severity, whereas the Japanese Orthopedic Association score was adopted to compare clinical outcome before and after surgery. Mean follow-up period was 38 months (range, 18 to 60). Ten patients had 5 levels of decompression (C3-7), and 17 patients had 4 (C3-6, 12 patients; C4-7, 5 patients). All patients experienced functional improvement of at least 1 Nurick score after surgery. The Japanese Orthopedic Association score increased significantly from 7.5+/-3.2 before surgery to 13.2+/-1.6 at final follow-up. Postoperative radiography and computed tomography scan demonstrated significantly increased sagittal diameter and canal expansion. No neurologic deterioration owing to hinge reclosure or major surgery-related complications were observed. In conclusion, unilateral open-door laminoplasty with suture anchor fixation effectively maintains expansion of the spinal canal and resists closure while preserving alignment and stability. This modified technique has a low complication rate and provides marked functional improvement in patients with cervical myelopathy owing to ossification of the posterior longitudinal ligament.

C5 Palsy After Laminectomy and Posterior Cervical Fixation for Ossification of Posterior Longitudinal Ligament

OBJECTIVE

To investigate the imaging findings correlated with C5 root palsies in the patients undergoing laminectomy and lateral mass screw fixation for ossification of posterior longitudinal ligament (OPLL), and clarify its pathogenic mechanism.

METHODS

The series included 49 patients with OPLL. Characteristics of preoperative and postoperative x-ray, computed tomography, and magnetic resonance images were compared between the patients with and those without C5 root palsies.

RESULTS

Postoperative C5 root palsies occurred in 9 patients 6 to 64 hours postoperatively. They tended to have increased cervical lordosis and severe OPLL. However, there was no significant positive correlation with an increase in T2-weighted hyperintense foci on magnetic resonance studies.

CONCLUSIONS

The tethering effect on the root seemed to be the main pathogenic mechanism of C5 root palsies in this study.

Assessing Range of Cervical Rotation After Laminoplasty Using Axial CT

PURPOSE

Although many authors have reported on cervical range of motion after laminoplasty, they have focused on flexion and extension based on lateral radiographs, not on axial rotation. In this study, we assessed cervical rotation from C1 to T1 after laminoplasty using computed tomography.

PATIENTS AND METHODS

Eighteen consecutive patients with cervical myelopathy who had undergone laminoplasty were observed. Patient was placed in the supine position on the computed tomography scan table. After the scans in this neutral position were completed, the patient actively rotated his neck as far as possible taking care that the shoulders remained in the horizontal plane. We measured the C1 to T1, C1 to C2, and C2 to T1 rotation angles preoperatively, and at 2 weeks and 6 months after surgery.

RESULTS

The average C1 to T1 rotation angles preoperatively were 46 degrees on the right and 45 degrees on the left. The percentage of C1 to C2 rotation during global cervical rotation (C1 to T1) was 62%. C1 to T1 rotation angle significantly decreased at two weeks after surgery but recovered to almost preoperative levels (11% decreases) by 6 months after surgery with no difference between right and left motion. The average C2 to T1 subaxial rotation angles did not significantly decreased after surgery.

CONCLUSIONS

Rotation angle after laminoplasty decreased slightly at 2 weeks after surgery but recovered almost to preoperative levels by 6 months. Subaxial rotation (C2 to T1) angles did not significantly decreased after surgery.

Importance of preserving the C7 spinous process and attached nuchal ligament in French-door laminoplasty to reduce postoperative axial symptoms

A comparative clinical trial was conducted to clarify the importance of preserving the C7 spinous process and attached nuchal ligament for the reduction of the axial symptoms after French-door laminoplasty in cervical spondylotic myelopathy patients. Forty-one cervical spondylotic myelopathy patients were enrolled. French-door laminoplasty from C3 to C7 in 22 patients (group 1), and from C3 to C6 in 19 patients (group 2) was performed. The whole structure of the C7 spinous process and the attached nuchal ligament were preserved in group 2. The pre- and post-operative evaluation regarding severity of clinical symptoms was assessed using the Japanese Orthopaedic Association (JOA) score. Pre-operative and subjective outcome regarding axial symptoms were also assessed using a visual analog pain scale questionnaire (VAS: 10-0, where a higher score indicates greater pain) at 1- and 2-year follow-up. Non-parametric testing (Mann-Whitney's U test) was used to establish differences between the two groups for categorical data (P < 0.05). There was no significant difference between the two groups in pre- and post-operative JOA score. The mean VAS was 5.6 +/- 1.4 in group 1, 5.4 +/- 1.7 in group 2 pre-operatively, and 6.4 +/- 1.7 in group 1 and 2.4 +/- 1.9 in group 2 at 1-year follow-up. The mean VAS score at 2-year follow-up exhibited 6.2 +/- 1.9 in Group 1, 2.3 +/- 1.8 in group 2. There was no significant difference in VAS between the two groups before surgery (P = 0.506), but significant differences were noticed at 1-year and 2-year follow-up (P < 0.05), indicating the presence of significantly fewer post-operative axial symptoms in group 2. Laminoplasty of the entire C7 structure is not necessary to obtain satisfactory recovery based on JOA score. Preservation of the C7 spinous process and the attached nuchal ligamentous structures is important to reduce post-laminoplasty axial symptoms.

Postoperative segmental C5 palsy after cervical laminoplasty may occur without intraoperative nerve injury: a prospective study with transcranial electric motor-evoked potentials

STUDY DESIGN

Intraoperative neurophysiologic monitoring with transcranial electric motor-evoked potentials was performed on patients who underwent cervical laminoplasty at a university hospital in a prospective study.

OBJECTIVE

To evaluate the usefulness of intraoperative spinal cord monitoring with transcranial electric motor-evoked potentials for prediction of the occurrence of segmental motor paralysis after cervical laminoplasty.

SUMMARY OF BACKGROUND DATA

Segmental motor paralysis occasionally occurs among patients who undergo expansive laminoplasty for cervical myelopathy, and it has been attributed to nerve root lesions caused by either a traumatic surgical technique or a tethering effect after decompression.

METHODS

Sixty-two consecutive patients (47 men and 15 women; mean age 64 years [range 32-89]) who were scheduled to undergo cervical laminoplasty under intraoperative spinal cord monitoring with transcranial electric motor-evoked potentials were included in this study. Transcranial electrical stimulations were delivered through pin-type electrodes, and the evoked potentials were recorded over the deltoid, biceps, and triceps muscles in the bilateral upper extremities and thoracic spinal cord.

RESULTS

Intraoperative evoked potentials were successfully recorded in all muscles in 57 patients (92%), and incomplete evoked potentials were recorded in the remaining 5 patients. No critical decrease in the amplitude of the evoked potentials was observed in any of the 62 patients. All patients showed sufficient postoperative recovery from their clinical symptoms; however, postoperative transient C5 palsy occurred in 3 patients.

CONCLUSIONS

No abnormalities were observed on transcranial electric motor-evoked potential monitoring, even in those patients who developed postoperative transient C5 palsy. These results suggest that the development of postoperative C5 palsy after cervical laminoplasty is not associated with intraoperative injury of the nerve root or the spinal cord, although the precise mechanism of its development is still unclear. Surgeons should be aware that C5 palsy is a possible complication of cervical laminoplasty, even in the absence of intraoperative nerve injury.

Long-term results of expansive open-door laminoplasty for cervical myelopathy--average 14-year follow-up study

STUDY DESIGN

Retrospective case series on long-term follow-up results of original expansive open-door laminoplasty for cervical myelopathy due to cervical spondylosis (CSM) and ossification of posterior longitudinal ligament (OPLL).

OBJECTIVES

To elucidate efficacy and problems of original open-door laminoplasty to improve future surgical outcomes.

SUMMARY OF BACKGROUND DATA

Little information is available on long-term outcomes of original open-door laminoplasty without grafts, implants, or instruments.

METHOD

The study group included 80 patients who underwent original open-door laminoplasty and were followed for minimum 10 years. Clinical results, including Japanese Orthopedic Association scores, recovery rates, occurrences of complications, and long-term deterioration were investigated. Cervical alignments, type of OPLL, cervical range of motion, anteroposterior diameter of spinal canal, and progression of OPLL were assessed on plain radiographs. Spinal cord decompression was verified on magnetic resonance imaging.

RESULTS

Average Japanese Orthopedic Association score and recovery rate improved significantly until 3 years after surgery and remained at an acceptable level in both cervical spondylosis and OPLL patients with slight deterioration after 5 years. Segmental motor palsy developed in 8 patients. Late deterioration, mainly lower extremity motor score decline, developed in 8 CSM and 16 OPLL patients. Overall cervical range of motion decreased by 36%. Patients with cervical lordosis decreased gradually in both patient groups. Such changes in alignments did not affect surgical results in CSM patients, while OPLL patients with preoperative kyphosis had lower recovery rates than those with straight and lordotic alignments. OPLL progression that was detected in 66% of patients did not affect clinical results. Although infrequent, magnetic resonance imaging revealed atrophy of spinal cord, spinal cord compression at adjacent segments due to degenerative changes and OPLL progression.

CONCLUSIONS

Long-term results of open-door laminoplasty without bone graft, graft substitutes, or instruments were satisfactory. However, segmental motor paralysis, kyphosis, established before and after surgery, OPLL progression, and late deterioration due to age-related degeneration remain challenging problems.

Prediction of spinal canal expansion following cervical laminoplasty: a computer-simulated comparison between single and double-door techniques

STUDY DESIGN

Laminoplasty was simulated using a computer-assisted technique to assess the amount of canal expansion.

OBJECTIVES

This study was designed to clarify the relationship between laminoplasty opening size and increase in sagittal canal diameter, increase in canal area, and the angle of the opened lamina following laminoplasty, and to determine whether a spinous process-splitting laminoplasty achieves the similar canal expansion as a single open-door method.

SUMMARY OF BACKGROUND DATA

Single and double-door cervical laminoplasty (SDCL and DDCL, respectively) have been widely used in the treatment of multilevel stenotic conditions. However, the relationship between laminoplasty opening size and spinal canal expansion following laminoplasty, and the comparison of postoperative spinal canal expansion between single and double-door techniques have not been well investigated.

METHODS

SDCL and DDCL, based on preoperative computerized tomography scans of 34 patients who had undergone the laminoplasty surgery, were simulated using a computer-assisted technique. Laminoplasty with an opening size of 6, 8, 10, 12, 14, 16, and 18 mm were simulated to determine the amount of canal enlargement with the various opening size.

RESULTS

Sagittal diameter, canal area, and lamina angle were increased steadily following either single or double-door laminoplasty with the door opened from 6 to 18 mm. Significant positive correlation was found between laminoplasty opening size and increase in sagittal diameter (R2 = 0.969 and P = 0.001 in SDCL; R2 = 0.926 and P < 0.001 in DDCL), increase in canal area (R2 = 0.961 and P < 0.001 in SDCL; R2 = 0.937 and P < 0.001 in DDCL), and lamina angle (R2 = 0.959 and P < 0.001 in SDCL; R2 = 0.943 and P < 0.001 in DDCL). No significant correlation was observed between preoperative sagittal diameter and increase in sagittal diameter of the spinal canal, whereas significant positive correlation was found between preoperative cross-section area and increase in cross-section area of the spinal canal. The differences between postoperative canal increase in sagittal diameter and canal area for the single versus double-door technique were statistically significant when the door was opened by more than 12 mm (P < 0.05).

CONCLUSIONS

Our investigation provides insight into canal expansion after laminoplasty. The increased amount of canal following laminoplasty can be predicted by the regression equations. This may allow preoperative determination of the optimal size of the opening needed to establish adequate canal space for the spinal cord. Both single and double-door techniques of laminoplasty provide sufficient room for posterior migration of the spinal cord, although gaining different canal expansion.

Laminoplasty: a review of its role in compressive cervical myelopathy

BACKGROUND CONTEXT

The currently accepted surgical treatments for compressive cervical myelopathy include both anterior and posterior decompression. Anterior approaches including multilevel discectomy with fusion or vertebral corpectomy with strut grafting, both with and without instrumentation, have enjoyed successful outcomes, but have been associated with select postoperative complications. Laminoplasty has been developed to decompress the spine posteriorly while avoiding the spinal destabilization seen after laminectomy.

PURPOSE

The purpose of this article is to provide a review of the various techniques, biomechanical basis, predictive value of imaging modalities, clinical outcomes, and postoperative complications associated with cervical laminoplasty.

STUDY DESIGN

A review of the literature.

METHODS

A comprehensive literature review using Medline was performed identifying relevant articles that addressed the techniques, clinical outcomes, and complications after cervical laminoplasty, as well as preoperative radiographic predictors of outcome.

RESULTS

The various modifications of cervical laminoplasty have generally been associated with excellent clinical outcomes when used for myelopathy secondary to cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL). Recent long-term studies have identified issues with this technique including axial neck pain, canal restenosis, nerve root palsy, diminished cervical motion, and loss of cervical lordotic alignment.

CONCLUSIONS

Cervical laminoplasty remains a reliable procedure for posterior decompression of the spine, but the optimal approach to cervical myelopathy must take into account both patient and disease characteristics, as well as the capabilities and experience of the surgeon.

Quantitative prediction of spinal cord drift after cervical laminectomy and arthrodesis

STUDY DESIGN

Retrospective review of radiographic parameters.

OBJECTIVES

To identify preoperative radiographic parameters that may be quantitatively predictive of postoperative spinal cord drift after cervical laminectomy and arthrodesis.

SUMMARY OF BACKGROUND DATA

Cervical laminectomy and arthrodesis can be an effective method to treat anterior compressions of the spinal cord if there is a sufficient posterior spinal cord drift after surgery. Preoperative cervical alignment has shown some correlations to the degree of spinal cord shift, but whether this and other preoperative radiographic parameters can be used to quantitatively predict the amount of spinal cord drift is unclear.

MATERIALS AND METHODS

Preoperative and postoperative radiographs (radiographs, MRIs, and CT) of patients who had cervical laminectomy and arthrodesis were reviewed retrospectively. Various radiographic parameters, including sagittal alignment, longitudinal distance index, space available for the spinal cord at cephalad or caudad levels, and distance from apex of the lordosis to the C2-C7 vertical line were measured. In the first cohort of patients, these parameters were correlated with mean postoperative spinal cord shift to identify any relationships. In the second cohort of patients, the identified association was used on preoperative imaging studies to attempt quantitative prediction of the postoperative spinal cord shift.

RESULTS

Space available for the spinal cord at the level immediately cephalad to the laminectomized segments had high correlations (R = 0.94) to the postoperative spinal cord shift. This association was used to quantitatively predict postoperative spinal cord shift within 11% +/- 6% of the measured value. If 4 mm of mean postoperative spinal cord shift is desired, the ratio to the available space and anterior posterior diameter of the spinal cord should be approximately 2.0.

CONCLUSION

Relative stenosis at the level directly cephalad to the laminectomized level can affect the degree of postoperative spinal cord shift. Preoperative axial imaging studies should be closely scrutinized to ensure that adequate space is available at the cephalad adjacent level to allow sufficient cord shift after decompressive laminectomy and arthrodesis.

Open-door laminoplasty for cervical myelopathy resulting from adjacent-segment disease in patients with previous anterior cervical decompression and fusion

STUDY DESIGN

This is a retrospective study of patients with cervical myelopathy resulting from adjacent-segment disease who were treated by open-door expansive laminoplasty.

OBJECTIVES

The purpose of this study was to evaluate the effectiveness of laminoplasty for cervical myelopathy resulting from adjacent-segment disease.

SUMMARY OF BACKGROUND DATA

Adjacent-segment disease is one of the problems associated with anterior cervical decompression and fusion. However, the optimal surgical management strategy is still controversial.

METHODS

Thirty-one patients who underwent open-door expansive laminoplasty for cervical myelopathy resulting from adjacent-segment disease and age- and sex-matched 31 patients with myelopathy who underwent laminoplasty as the initial surgery were enrolled in the study. The pre- and postoperative Japanese Orthopedic Association scores (JOA scores) and the recovery rate were compared between the two groups.

RESULTS

The average JOA scores in the patients with adjacent-segment disease and the controls were 9.2 +/- 2.6 and 9.4 +/- 2.3 before the expansive laminoplasty and 11.9 +/- 2.8 and 13.3 +/- 1.7 at the follow-up examination, respectively; the average recovery rates in the two groups were 37.1 +/- 22.4% and 50.0 +/- 21.3%, respectively (P = 0.04). The mean number of segments covered by the high-intensity lesions on the T2-weighted magnetic resonance images was 1.87 and 0.9, respectively (P = 0.001).

CONCLUSIONS

Moderate neurologic recovery was obtained after open-door laminoplasty in patients with cervical myelopathy resulting from adjacent-segment disc disease, although the results were not as satisfactory as those in the control group. This may be attributed to the irreversible damage of the spinal cord caused by persistent compression at the adjacent segments.

Segmental instability in cervical spondylotic myelopathy with severe disc degeneration

STUDY DESIGN

A retrospective study was conducted.

OBJECTIVE

To investigate relationships between severe disc degeneration (SDD) and segmental instability in cervical spondylotic myelopathy (CSM) and to discuss surgical treatment for CSM with severe disc degeneration.

SUMMARY OF BACKGROUND DATA

Information on relationships between segmental instability and spinal cord compression in CSM with severe disc degeneration is scarce.

METHODS

Radiographs and magnetic resonance images of patients with CSM with (n = 42) and without (n = 75) SDD were reviewed retrospectively. Cervical instability and spinal cord compression factors were analyzed. Outcomes of anterior cervical decompression and fusion (ACDF) and expansive laminoplasty (ELAP) were evaluated in medical records of follow-up clinics.

RESULTS

Segmental instability was found in 71.4% of patients with SDD and 22.7% of patients without SDD. Spinal cord compression was found at the intervertebral space of SDD and upper adjacent disc space. The recovery rate of ACDF and ELAP was 60.8% and 57.1%, respectively.

CONCLUSION

The upper adjacent vertebra above SDD has inclination of segmental instability. There is static spinal cord compression in intervertebral spaces of SDD and dynamic compression in upper adjacent intervertebral spaces. Multilevel anterior cervical decompression and fusion or expansive laminoplasty should be used for surgical treatment.

Delayed segmental motor paralysis following laminoplasty: two case reports

STUDY DESIGN

Two patients who experienced the onset of segmental motor paralysis several years after laminoplasty are presented.

OBJECTIVES

To discuss the mechanism of development of delayed segmental motor paralysis following laminoplasty.

SETTING

A department of orthopaedic surgery in Japan.

METHODS

One patient experienced motor weakness in his deltoid and biceps muscles on the left side 5 years after laminoplasty. The other patient noticed motor weakness in his deltoid and biceps on the right side 7 years after laminoplasty. CT myelography revealed posterior spur formation and hypertrophic facet joints on the hinged side at the C4-C5 level in both patients.

RESULTS

Posterior foraminotomy was performed at the C4-C5 level on the hinged side in both patients. Postoperatively, motor weakness in the deltoid and biceps muscles was improved in both patients.

CONCLUSIONS

Although spondylotic changes, including spur formation and disc herniation, have occasionally developed in operated segments after laminoplasty, few patients have required additional surgery for treatment of relapse of neurological deficits. It has been believed that spinal cord is rarely compressed by the spondylotic changes since it shifts posteriorly in the enlarged spinal canal. However, laminoplasty disturbs the facet joints since the medial portion of dorsal cortex and cancellous bone in facet joints is drilled out to make a trough. Facet joints disturbed in this fashion undergo degeneration over time after surgery. Nerve roots may occasionally be compressed by degenerated facet joints and spurs that have developed at the entrance of root canal, resulting in segmental motor paralysis several years after laminoplasty. Careful long-term observation is necessary after this procedure.

Spinal stenosis due to ossified lumbar lesions

OBJECT

Spinal stenosis due to lumbar ossified lesions is a rare pathological entity. The authors retrospectively evaluated the clinical features and surgical results associated with cases involving lumbar ossified lesion-induced stenosis.

METHODS

Data obtained in 20 surgically treated patients with lumbar hyperostotic spinal stenosis were included. To evaluate the background of the disease, body mass index and general complications were assessed. Whole-spine radiological examination was conducted. The presence of ossification of the posterior longitudinal ligament or ossification of the ligamentum flavum was evaluated. Surgical results were classified according to the Japanese Orthopaedic Association (JOA) scale. In the patients in whom neurological deterioration was observed during follow up, the causes of deterioration were reviewed. Seven patients (35%) were obese and six patients (30%) suffered diabetes mellitus. Twelve patients harbored coexisting cervical and/or thoracic ossified lesions. The overall mean JOA score improved from 10.2 to a peak of 22.5; at last follow-up examination the mean JOA score was 20.9. In female and older patients with a long history of preoperative symptoms, a low preoperative JOA score, and other spinal lesions, recovery tended to be poorer. Recovery was poor in one patient, and neurological deterioration due to coexisting ossified spinal lesions occurred in another patient during the follow-up period.

CONCLUSIONS

Because coexisting ossified lesions were frequently seen, whole-spine analysis is recommended. Early diagnosis and appropriate treatment are important to achieve a better surgical outcome.

Is posterior spinal cord shifting by extensive posterior decompression clinically significant for multisegmental cervical spondylotic myelopathy?

STUDY DESIGN

Posterior cervical spinal cord shifting after selective single laminectomy associated with partial laminotomies was compared with that after bilateral open-door laminoplasty between the C3 and C7 levels in relation to the clinical results of each procedure.

OBJECTIVES

To investigate the clinical significance of posterior spinal cord shifting after extensive cervical laminoplasty.

SUMMARY OF BACKGROUND DATA

Current techniques used for cervical laminoplasty for multisegmental cervical spondylotic myelopathy (CSM) are consecutively performed between the C3 and C6 or C7 levels with expectation that the spinal cord will shift backward to keep it clear of anterior compression. However, the clinical significance of the posterior spinal cord shifting remains controversial, and there has been no report verifying it by comparing limited posterior decompression procedures with conventional extensive ones.

METHODS

Twenty-six patients with consecutive 2- to 3-level CSM who underwent selective laminoplasty (Group A) were enrolled in the study, and among 56 CSM patients who underwent bilateral open-door laminoplasty between the C3 and C7 levels, 25 who had consecutive 2- or 3- level stenosis identified by preoperative magnetic resonance imaging were used as controls (Group B). The recovery rate was calculated using preoperative and postoperative Japanese Orthopedic Association (JOA) scores for each patient, and for each patient's magnetic resonance imaging, the postoperative cervical curvature index was obtained according to Ishihara's method and the magnitude of postoperative backward shifting of the spinal cord was measured.

RESULTS

There was no significant difference between the subjects in Groups A and B with respect to the spinal curvature index, preoperative JOA scores, and recovery rate, but the magnitude of the postoperative posterior shifting of the spinal cord was greater for those in Group B than for those in Group A. There was no correlation between the recovery rate and posterior shifting of the spinal cord for each group, and no correlation was also found between the curvature index and posterior shifting of the spinal cord.

CONCLUSIONS

The outcome of posterior decompression surgery for multisegmental CSM is not correlated with the magnitude of postoperative backward shifting of the spinal cord. Extensive and consecutive decompression performed in conventional cervical laminoplasties is therefore not always necessary for multisegmental CSM.

Long-term results after expansive open-door laminoplasty for the segmental-type of ossification of the posterior longitudinal ligament of the cervical spine: a comparison with nonsegmental-type lesions

OBJECT

The segmental-type of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine is distinct from other types in its morphological features. Whether the results of expansive open-door laminoplasty for the segmental-type are different from those for other types remains unclear. To clarify this issue, the long-term results after surgical treatment of segmental-type OPLL were compared with those of other types.

METHODS

Clinical results were documented in 57 patients who underwent expansive open-door laminoplasty and were followed for a minimum of 7 years, results were quantified using the Japanese Orthopaedic Association (JOA) scoring system to determine function. Segmental-type OPLL was observed in 10 patients (Group 1) and other types in 47 patients (Group 2). Preoperative JOA scores were not significantly different between the two groups. As many as 5 years after surgery, clinical results were favorable and maintained in both groups, and no significant intergroup difference in postoperative JOA scores was observed; however, after 5 years postoperatively, JOA scores decreased in both groups. The decrease was greater in Group 1, and a significant intergroup difference in JOA scores was demonstrated when analyzing final follow-up data. In Group 1, the authors found that the degree of late-onset deterioration relating to cervical myelopathy positively correlated with the cervical range of motion.

CONCLUSIONS

The long-term results of expansive open-door laminoplasty in the treatment of segmental-type OPLL were inferior to those for other types. Cervical mobility may contribute to the development of late deterioration of cervical myelopathy.

Technical Improvements and Results of Open-door Expansive Laminoplasty with Hydroxyapatite Implants for Cervical Myelopathy

OBJECTIVE:

A new, modified technique of cervical open-door laminoplasty with hydroxyapatite implants was developed to enlarge the spinal canal in stable fashion yet preserve the architecture of the cervical spine and surrounding tissues. To assess the efficacy of this technique, a retrospective review of neurological and radiological outcomes after cervical laminoplasty was conducted.

METHODS:

Clinical charts and cervical x-rays of 151 patients with cervical stenotic myelopathy were reviewed. Patients were treated with the cervical laminoplasty between May 2001 and January 2002. The patient group comprised 69 women and 82 men ranging in age from 30 to 86 years (mean, 63 yr). Neurological outcomes were evaluated according to the Japanese Orthopaedic Association grade. To assess alignment and mobility of the cervical spine, the C2–C7 angle was used.

RESULTS:

The average Japanese Orthopaedic Association grade was 8.1 ± 2.5 before surgery and 15.2 ± 1.5 at 1 year after surgery (P &lt; 0.01). No neurological complications were observed. The average C2–C7 angle at the neutral position increased from 8.3 ± 11.7 degrees before surgery to 14.9 ± 11.6 degrees at 1 year after surgery (P &lt; 0.01). The range of motion between C2 and C7 was 36.9 ± 12.5 degrees and 29.1 ± 10.8 degrees before and 1 year after surgery, respectively.

CONCLUSION:

A new modified technique of cervical open-door laminoplasty described herein offers some solutions to the problems associated with conventional techniques of cervical laminoplasty.

Multicenter study investigating the postoperative progression of ossification of the posterior longitudinal ligament in the cervical spine: a new computer-assisted measurement

OBJECT

Ossification of the posterior longitudinal ligament (OPLL) often progresses after surgery, and this may cause late-onset neurological deterioration. There have been few studies, however, to clarify any correlation between progression and clinical outcome, partly because of the lack of studies involving reliable and reproducible methods by which detection of progression is made possible. The authors conducted a multicenter study to investigate the occurrence of postoperative progression and to elucidate the possible risk factors in a large-scale patient population, and a novel computer-assisted measurement method was used to provide the basis for future clinical studies.

METHODS

The authors analyzed lateral plain radiographs obtained immediately and at 1 and 2 years after surgery in 131 patients who underwent posterior decompression at 13 institutions. The x-ray films were transformed via scanner into digital images; the length and thickness of ossifications were measured using a new computer-assisted measurement system, and the incidence of progression was determined. Odds ratios for progression according to age group and types of OPLL were determined and compared to elucidate significant risk factors of progression.

CONCLUSIONS

This is the first multicenter study to investigate the incidence of OPLL progression after posterior decompression by using a standardized measurement method. The rate of postoperative progression at 2 years was 56.5%, which was comparable with results reported in other studies. Progression occurred more frequently in younger-age rather than in older-age patient populations at both 1 and 2 years postoperatively. Mixed-type and continuous-type OPLL progressed more frequently than the segmental-type lesion at 2 years. The results of the present study could serve as basis for future studies to assess the efficacy of drug therapy to prevent OPLL progression.

Computer-assisted measurement of the size of ossification in patients with ossification of the posterior longitudinal ligament in the cervical spine

BACKGROUND

Progression of ossification of the posterior longitudinal ligament in patients may lead to serious neurological deterioration. A government-funded study group established a manual method of measurement on plain radiographs to detect progression of the ossified lesion. However, this method did not gain wide acceptance because it was time-consuming and complicated, for which drawings of many lines and points are required. We have applied a computer-assisted measurement system to this task and have evaluated inter- and intraexaminer reliability, showing that it is quicker to use and more accurate than the manual method.

METHODS

Eight board-certified spine surgeons, acting as the examiners, measured the sizes of the ossified lesions on nine lateral cervical spine radiographs using the computer-assisted measurement system. Following insertion of digitized radiographic image data into a computer, the corners of the vertebral bodies on the displayed images are marked by the examiners, and the software automatically sets reference lines and points. The examiners identify upper, lower, and posterior margins of the ossified lesions, and the software calculates the dimensions of the ossified lesions. Data obtained from eight examiners for length and thickness underwent rigorous statistical analysis by calculating the intraclass correlation coefficients with 95% confidence intervals (CIs) to determine interexaminer reliability and Pearson's correlation coefficients between the two measurements by the same examiner to determine intraexaminer reliability.

RESULTS

The intraclass correlation coefficients were 0.927 and 0.968 with 95% CIs of 0.883-0.955 and 0.956-0.978 for measurements of length and thickness, respectively, of the ossified lesions. The Pearson's correlation coefficients for the two measurements by the same examiners were 0.943-0.985 for length and 0.957-0.991 for thickness.

CONCLUSIONS

The inter- and intraexaminer reliability using this measurement system was excellent. The method can detect progression of ossification of the posterior longitudinal ligament (OPLL) on plain radiographs with high precision and could become a standard method for measuring the size of OPLL.

Can laminoplasty maintain the cervical alignment even when the C2 lamina is contained?

STUDY DESIGN

Retrospective case-controlled study of cervical laminoplasty.

OBJECTIVE

To evaluate the alignment and clinical result by laminoplasty when the C2 lamina is contained or retained.

SUMMARY OF BACKGROUND DATA

Resection of the C2 lamina was reported to progress to kyphosis after laminectomy. Laminoplasty was reported to inhibit kyphosis. But no study has ever shown if the alignment is retained when laminoplasty also included the C2 lamina.

METHODS

Seventy-two patients with cervical spondylotic myelopathy undergoing laminoplasty were analyzed. Follow-up averaged 4.0 years. The outcome was assessed by the Cobb angle between C2 and C7, and the motor function scores of the upper and lower extremities for cervical myelopathy were made by the Japanese Orthopedic Association. Patients were stratified into three groups depending on the handling of the C2 lamina: fully split (S group; n = 17), C2 dome-like laminotomy (D group; n = 19), and intact (I group; n = 36). Change of the C2-C7 angle was compared by the analysis of variance and post hoc test. The association between the alignment and the motor scores was analyzed.

RESULTS

Upper/lower score increased from 2.4/2.0 to 3.4/2.9, respectively. The C2-C7 angle decreased in S group: -8.3 degrees , D group: -5.2 degrees , and I group: -1.5 degrees . The cervical alignment deteriorated significantly in S group compared with the I group (P < 0.01). The C2-C7 angle change or postoperative C2-C7 angle had no significant correlation with the postoperative upper and lower m-JOA scores or score change.

CONCLUSIONS

Subaxial laminoplasty maintained the alignment. But if laminoplasty included the C2 lamina, the alignment worsened.

Clinical outcomes following cervical laminoplasty for 204 patients with cervical spondylotic myelopathy

BACKGROUND

Laminoplasty is a well-recognized technique for decompressing the cervical spine in cases of spondylotic myelopathy and ossification of the posterior longitudinal ligament. This technique, originally popularized in Asia, is becoming more widespread, but to date there have been few reports of clinical series from North American centers.

METHODS

Retrospectively we reviewed (1986-2001) 204 cases of open door laminoplasty. All patients presented with symptoms and magnetic resonance imaging (MRI) findings consistent with myelopathy secondary to multisegmental cervical stenosis with spondylosis and underwent decompression from C3 to C7. Improvement in myelopathy was assessed with the Nurick Score.

RESULTS

Average age was 63 years (range 36 to 92). Follow-up averaged 16 months. Postoperatively, Nurick scores improved by 1 point in 78 patients, 2 points in 37 patients, 3 points in 7 patients, and 4 points in 5 patients; 74 patients experienced no improvement, and 3 patients deteriorated by one point. There was no statistical difference in myelopathy outcomes when comparing patients older and younger than 75 years of age. In two patients there was radiographic progression of kyphosis, but in no case was subsequent fusion required. Six patients without neck pain preoperatively developed new intractable neck pain after surgery.

CONCLUSIONS

Open door expansile laminoplasty is a safe and effective method for treating cervical spondolytic myelopathy. Laminoplasty is thus an alternative to anterior surgery that can be accomplished quickly with minimal blood loss, minimizing risks in elderly patients.

Long-term results of expansive open-door laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine

OBJECT

Numerous surgical procedures have been developed for treatment of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine, and these can be performed via three approaches: anterior, posterior, or combined anterior-posterior. The optimal approach in cases involving OPLL-induced cervical myelopathy, however, remains controversial. To address this issue, the authors assessed the benefits and limitations of expansive open-door laminoplasty for OPLL-related myelopathy by evaluating mid- and long-term clinical results.

METHODS

Clinical results obtained in 72 patients who underwent expansive open-door laminoplasty between 1983 and 1997 and who were followed for at least 5 years were assessed using the Japanese Orthopaedic Association (JOA) scoring system. The mean preoperative JOA score was 9.2 +/- 0.4; at 3 years postoperatively, the JOA score was 14.2 +/- 0.3 and the recovery rate (calculated using the Hirabayashi method) was 63.1 +/- 4.5%, both having reached their highest level. These favorable results were maintained up to 5 years after surgery. An increase in cervical myelopathy due to progression of the ossified ligament was observed in only two of 30 patients who could be followed for more than 10 years. Severe surgery-related complications were not observed. Preoperative JOA score, age at the time of surgery, and duration between onset of initial symptoms and surgery affected clinical results.

CONCLUSIONS

Mid-term and long-term results of expansive open-door laminoplasty were satisfactory. Considering factors that affected surgical results, early surgery is recommended for OPLL of the cervical spine.

The nuchal ligament restrains cervical spine flexion

STUDY DESIGN

A biomechanical study using a cadaver model was conducted to define the function of the nuchal ligament in the restraint of flexion of the cervical spine.

OBJECTIVE

To test the hypothesis that surgical resection of the nuchal ligament significantly reduces the structural restraints to cervical flexion.

SUMMARY OF BACKGROUND DATA

Although previous studies have examined the role of the posterior ligaments and capsules on cervical stability, no prior study has quantified the biomechanical significance of the nuchal ligament. The clinical significance may include progressive loss of lordosis or even kyphosis after trauma or posterior surgical procedures such as laminectomy, laminoplasty, or tumor resection.

METHODS

Cervical spines from the occiput to the first thoracic vertebra were harvested from 12 human cadavers. Specimens were tested under 3 conditions: all ligaments intact, after resection of the nuchal ligament, and then after additional resection of the supraspinous, interspinous, and yellow ligaments. Flexion moments were applied; load and displacement were measured. Changes in flexion range of motion and tangent stiffness between treatment conditions were statistically compared.

RESULTS

The flexion range increased 28% after removing the nuchal ligament. After subsequent resections, the flexion range increased 52% compared with intact (P <0.005). Tangent stiffness decreased 27% after nuchal ligament resection; after all resections, stiffness was 35% lower than intact (P <0.05).

CONCLUSION

Resection of the nuchal ligament increased the flexion range of motion and decreased stiffness in flexion. Injury to the nuchal ligament may increase the risk of cervical spine instability and malalignment.

Suspended laminoplasty for wide posterior cervical decompression and intradural access: results, advantages, and complications

Object. Cervical laminoplasty is a recognized technique commonly used for multilevel posterior cervical decompression, and it is favored over laminectomy for maintaining spinal stability. Traditional hinge techniques, however, limit lateral exposure on one side and can limit dural exposure. The authors present their experience with a modified laminoplasty technique incorporating complete laminectomy and placement of titanium miniplate instrumentation. This method allows wide bilateral posterior decompression and unobscured dural access.

Methods. Twenty-eight patients (mean age 57 years) underwent cervical laminoplasty during a 4-year period. Twenty-seven patients presented with progressive cervical myelopathy. Seventeen patients (61%) had degenerative spondylotic stenosis; nine (32%) underwent resection of an intradural neoplasm. A mean of 3.5 levels were exposed and reconstructed. The follow-up period ranged from 4 months to 4 years (mean 15 months). The mean angular extension—flexion displacement measured between C-1 and C-7 was unchanged postoperatively, with preserved mobility across laminoplasty-treated segments in all patients. The anteroposterior diameter of the spinal canal increased 3.6 mm (27.2%) postoperatively (p = 0.004). In one patient an asymptomatic postoperative kyphosis developed. There were five cases of postoperative infection. One superficial infection resolved after intravenous antibiotic therapy alone, and four deep infections required surgical reexploration.

Conclusions. The advantages of this technique over other laminoplasty methods include wide lateral spinal canal and intradural access, as well as preserved motion with partial restoration of the posterior tension band.

Open-door Cervical Expansile Laminoplasty

CERVICAL LAMINOPLASTY IS becoming a popular technique for the treatment of cervical myelopathy that is the result of multilevel canal stenosis. Many variations in this technique, which was originally created in Japan, have been developed, all with the goal of increasing canal space and reconstructing the posterior bony arch. We describe our extensive experience with this procedure for the treatment of cervical spondylotic myelopathy.

C5 palsy after decompression surgery for cervical myelopathy: review of the literature

STUDY DESIGN

A literature review was conducted to integrate and compile available reports on postoperative C5 palsy.

OBJECTIVES

To review the clinical features, possible pathogenesis, and procedures for treatment and prevention of postoperative C5 palsy as a complication of surgery for cervical compression myelopathy.

SUMMARY OF BACKGROUND DATA

Although postoperative C5 palsy develops in approximately 5% of patients after decompression surgery of the cervical spine, its pathogenesis and the options for prevention and treatment remain unidentified and many controversies exist.

METHOD

We reviewed and analyzed papers published from 1986 to 2002 regarding C5 palsy as a postoperative complication. Statistical comparisons were made when appropriate.

RESULTS

Postoperative C5 palsy is reported to occur in an average of 4.6% of patients after surgery for cervical compression myelopathy. No significant differences were noted between patients undergoing anterior decompression and fusion and laminoplasty, nor were distinctions apparent between unilateral hinge laminoplasty and French-door laminoplasty, or between cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament. Two theories were put forth to account for the pathogenesis of C5 palsy: nerve root injury and segmental spinal cord disorder. Neither of these hypotheses has been consistently supported and evidence to refute each hypothesis can be found in the literature. Recently, surgeons have advocated foraminotomy combined with laminoplasty to prevent or treat C5 palsy, but further studies into the efficacy of this procedure are needed. Although patients with C5 palsy generally have a good prognosis for neurologic and functional recovery, those with severe paralysis require significantly longer recovery times when compared to more mild cases.

CONCLUSION

The incidence of postoperative C5 palsy has been reported at 4.6% after surgery for cervical compression myelopathy and this value has not varied with different surgical procedures or disease etiologies. The pathogenesis of postoperative C5 palsy remains unclear at the present time. Patients with postoperative C5 palsy generally have a good prognosis for functional recovery, but the severely paralyzed cases required significantly longer recovery times than the mild cases.

Pathomechanism of myelopathy and surgical results of laminoplasty in elderly patients with cervical spondylosis

STUDY DESIGN

Clinical and radiologic analyses in elderly patients with cervical myelopathy.

OBJECTIVE

To investigate the pathomechanism of cervical myelopathy and the surgical results of laminoplasty in elderly patients older than 70 years old.

SUMMARY OF BACKGROUND DATA

To date, there have been no reports on the pathomechanism of cervical myelopathy in elderly patients. Further, the surgical results and postoperative complications of laminoplasty have not been fully evaluated in elderly patients.

METHODS

Eighty-nine patients who underwent cervical laminoplasty were reviewed. The patients were divided into 2 groups according to the age at the time of operation (the elderly patient group: 20 patients who were older than 70 years old, and the control group: 69 patients who were younger than 69 years old). Pre- and postoperative neurologic status (the Japanese Orthopedic Association score) and postoperative complications were compared between the two groups. Radiologic features were also examined.

RESULTS

There was no statistical difference in the recovery rate of Japanese Orthopedic Association score between the elderly patient group and the control group. Activities of daily living improved in the elderly patients. Several complications, such as delirium and worsening hypertension, were found in the elderly patient group. In the preoperative radiographs, the incidence of either retrolisthesis or anterolisthesis in the elderly patient group was significantly higher than that in the control group.

CONCLUSIONS

Retrolisthesis and anterolisthesis are often the cause of myelopathy in elderly patients. Surgical decompression for cervical myelopathy was beneficial even in elderly patients older than 70 years old. Laminoplasty achieves stability of the cervical spine, and this procedure is reasonable for the treatment.

Preventing C5 palsy after laminoplasty

STUDY DESIGN

The incidences of postoperative C5 palsy between a group treated by a standardized diagnostic and surgical treatment and a control group treated by a different cervical laminoplastic technique were prospectively compared.

OBJECTIVE

To investigate the cause, risk factors, and prevention of C5 palsy after laminoplasty for cervical myelopathy.

SUMMARY OF BACKGROUND DATA

No one factor could predict postoperative C5 palsy, although postoperative C5 palsy is a clinically significant complication of cervical laminoplasty.

METHODS

One hundred eleven patients who underwent laminoplasty for cervical myelopathy were studied. Seventy-four patients who consulted two spinal surgeons (two of the authors) were placed into Group A. Thirty-seven patients who consulted the other two spinal surgeons (the other two authors) were placed into Group B. There were no statistical differences between the two groups for age at operation, gender, spinal disorders, preoperative neurologic severity, and length of the follow-up period. All patients in Group A underwent preoperative electromyographic testing. Patients with no electromyographic abnormalities underwent a standard midsagittal laminoplasty. Those with preoperative electromyographic abnormalities, reflecting a subclinical radiculopathy, underwent a modified en bloc laminoplasty with microcervical foraminotomy done at each level of the EMG abnormality. All Group B patients underwent midsagittal laminoplasty without preoperative electromyographic testing. Microcervical foraminotomy was performed for C5 root in 11 patients (14.9%) of Group A.

RESULTS

No patients in Group A and three patients (8.1%) in Group B experienced postoperative C5 palsy. This difference was statistically significant (P = 0.035, Fisher's exact method).

CONCLUSIONS

Electromyography is a sensitive predictor of postoperative C5 palsy after laminoplasty. This complication may be avoided by performing selective foraminotomy in addition to posterior central canal decompression. Preexisting subclinical C5 root compression is a cause of C5 palsy after posterior cervical decompression for myelopathy.

Adjacent segment disease: an uncommon complication after cervical expansile laminoplasty: case report

OBJECTIVE AND IMPORTANCE

Adjacent segment disc disease is a well-described phenomenon that occurs after anterior cervical spinal fusion. One of the advantages of cervical laminoplasty over anterior approaches is that although the treated segments are stiffened, no formal fusion is performed. This is thought to reduce the biomechanical stresses placed on adjacent levels and thus decrease the likelihood of adjacent level degeneration.

CLINICAL PRESENTATION

A 62-year-old man presented with myelopathy attributable to cervical spondylosis and underwent a C3-C7 laminoplasty. Improvements in gait were followed 2 years later by symptomatic disc degeneration and spinal cord compression at T1-T2, which rendered him wheelchair bound.

INTERVENTION

The patient was treated with a laminectomy at the level of stenosis accompanied by posterior instrumentation and fusion from C5 to T3. This resulted in clinical improvement, and the patient was returned to his baseline ambulatory status.

CONCLUSION

Adjacent segment disease is an uncommon complication that occurs after laminoplasty. Careful attention to preserving facet joint motion in the cervical spine may minimize the stresses placed on adjacent motion segments.

Surgery for postarthrodesis adjacent–cervical segment degeneration

Anterior cervical decompression and fusion has gained popularity because of its applicability to a variety of cervical spine disorders. The authors of long-term follow-up studies have demonstrated the development of degenerative changes in segments adjacent to fusion. So-called adjacent-segment disease causes symptomatic deterioration in up to 25% of the patients who have undergone anterior cervical decompression and fusion for cervical spondylotic myelopathy. The causes of this condition are debated in the literature. The authors provide a review of the available literature on the pathogenesis, prevention, and treatment of postarthrodesis adjacent-segment degenerative disease.

Operative treatment of the patient with neck pain

Most patients with axial neck pain and cervical radiculopathy can be managed conservatively. Surgical intervention for radiculopathy is considered only when conservative management has failed unless the neurologic deficits are very significant. In cases of myelopathy, surgery may be considered earlier, but if the myelopathy is mild, conservative treatment and close observation are still appropriate. For patients with axial neck pain, surgery is generally not considered except for rare cases caused by single- or two-level degenerative disk disease with severe and unrelenting pain. There are many surgical options for the patients with the degenerative cervical spine, but the indications are different. Surgical intervention involves a complete understanding of the disease process both from physical examination and from radiographic studies. If surgery is undertaken without appropriate clinical correlation, poor results often occur. Although the operative planning is the responsibility of the surgeon. the referring physician should also have some awareness of the basic principles behind the different surgeries.

Local kyphosis reduces surgical outcomes of expansive open-door laminoplasty for cervical spondylotic myelopathy

STUDY DESIGN

This retrospective study analyzed the effects of cervical alignment on surgical results of expansive laminoplasty (ELAP) for cervical spondylotic myelopathy (CSM).

OBJECTIVE

To determine the limitation of posterior decompression by ELAP for CSM in the presence of local kyphosis.

SUMMARY OF BACKGROUND DATA

Several studies have reported that cervical malalignment affected surgical outcomes of ELAP. However, there has been no report to demonstrate crucial determinants of surgical outcomes of ELAP for CSM in relation to cervical sagittal alignment.

METHODS

The study group comprised 114 patients who underwent ELAP for CSM. All were followed up for more than 2 years. The Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy (full score, 17 points) was used to evaluate surgical outcomes for each patient 2 years after surgery. Statistical analysis with multivariate logistic regression models was used to ascertain the risk factors affecting postoperative surgical outcomes.

RESULTS

The average JOA scores were 9.9 points before surgery and 14 points 2 years after surgery. The recovery rate was 60.2%. Statistical analysis showed that signal intensity change on MRI and local kyphosis were the most crucial risk factors for poor surgical outcomes. Calculated with the logistic regression model, the highest risk of poor recovery was local kyphosis exceeding 13 degrees.

CONCLUSIONS

The influence of cervical malalignment on neurologic recovery after ELAP for CSM was shown. When patients have local kyphosis exceeding 13 degrees, anterior decompression or posterior correction of kyphosis as well as ELAP should be considered. Expansive laminoplasty for CSM is best indicated for patients with local kyphosis less than 13 degrees.

Laminectomy and Posterior Cervical Plating for Multilevel Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament: Effects on Cervical Alignment, Spinal Cord Compression, and Neurological Outcome

OBJECTIVE

Multilevel anterior decompressive procedures for cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament may be associated with a high incidence of neurological morbidity, construct failure, and pseudoarthrosis. We theorized that laminectomy and stabilization of the cervical spine with lateral mass plates would obviate the disadvantages of anterior decompression, prevent the development of kyphotic deformity frequently seen after uninstrumented laminectomy, decompress the spinal cord, and produce neurological results equal or superior to those achieved by multilevel anterior procedures.

METHODS

We retrospectively reviewed the records of 38 patients who underwent laminectomy and lateral mass plating for cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament between January 1994 and November 2001. Seventy-six percent of patients had spondylosis, 18% had ossification of the posterior longitudinal ligament, and 5% had both. Clinical presentation included upper extremity sensory complaints (89%), gait difficulty (70%), and hand use deterioration (67%). Spasticity was present in 83%, and weakness of one or more muscle groups was seen in 79%. Spinal cord signal abnormality on sagittal T2-weighted magnetic resonance imaging (MRI) was seen in 68%. Neurological evaluation was performed using a modification of the Japanese Orthopedic Association Scale for functional assessment of myelopathy, the Cooper Scale for separate evaluation of upper and lower extremity motor function, and a five-point scale for evaluation of strength in individual muscle groups. Lateral cervical spine x-rays were analyzed using a curvature index to determine maintenance of alignment. Each surgically decompressed level was graded on a four-point scale using axial MRI to assess the adequacy of decompression. Late follow-up was conducted by telephone interview.

RESULTS

Laminectomy was performed at a mean 4.6 levels. Follow-up was obtained at a mean of 30.2 months after the procedure. The score on the modified Japanese Orthopedic Association scale improved in 97% of patients from a mean of 12.9 preoperatively to 15.58 postoperatively (P&lt; 0.0001). In the upper extremities, function measured by the Cooper Scale improved from 1.8 to 0.7 (P&lt; 0.0001), and in the lower extremities, function improved from 1.0 to 0.4 (P&lt; 0.0002). There was a statistically significant improvement in strength in the triceps (P&lt; 0.0001), iliopsoas (P&lt; 0.0002), and hand intrinsic muscles (P&lt; 0.0001). X-rays obtained at a mean of 5.9 months after surgery revealed no change in spinal alignment as measured by the curvature index. There was a decrease in the mean preoperative compression grade from 2.46 preoperatively to 0.16 postoperatively (P&lt; 0.0001). There was no correlation between neurological outcome and the presence of spinal cord signal change on T2-weighted MRI scans, patient age, duration of symptoms, or preoperative medical comorbidity.

CONCLUSION

Multilevel laminectomy and instrumentation with lateral mass plates is associated with minimal morbidity, provides excellent decompression of the spinal cord (as visualized on MRI), produces immediate stability of the cervical spine, prevents kyphotic deformity, and precludes further development of spondylosis at fused levels. Neurological outcome is equal or superior to multilevel anterior procedures and prevents spinal deformity associated with laminoplasty or noninstrumented laminectomy.

Cervical laminoplasty: a critical review

OBJECT

The technique of cervical laminoplasty was developed to decompress the spinal canal in patients with multi-level anterior compression caused by ossification of the posterior longitudinal ligament or cervical spondylosis. There is a paucity of data confirming its superiority to laminectomy with regard to neurological outcome, preserving spinal stability, preventing postlaminectomy kyphosis, and the development of the "postlaminectomy membrane."

METHODS

The authors conducted a metaanalysis of the English-language laminoplasty literature, assessing neurological outcome, change in range of motion (ROM), development of spinal deformity, and complications. Seventy-one series were reviewed, comprising more than 2000 patients. All studies were retrospective, uncontrolled, nonrandomized case series. Forty-one series provided postoperative recovery rate data in which the Japanese Orthopaedic Association Scale was used for assessing myelopathy. The mean recovery rate was 55% (range 20-80%). The authors of 23 papers provided data on the percentage of patients improving (mean approximately 80%). There was no difference in neurological outcome based on the different laminoplasty techniques or when laminoplasty was compared with laminectomy. There was postlaminoplasty worsening of cervical alignment in approximately 35% and with development of postoperative kyphosis in approximately 10% of patients who underwent long-term follow-up review. Cervical ROM decreased substantially after laminoplasty (mean decrease 50%, range 17-80%). The authors of studies with long-term follow up found that there was progressive loss of cervical ROM, and final ROM similar to that seen in patients who had undergone laminectomy and fusion. In their review of the laminectomy literature the authors could not confirm the occurrence of postlaminectomy membrane causing clinically significant deterioration of neurological function. Postoperative complications differed substantially among series. In only seven articles did the writers quantify the rates of postoperative axial neck pain, noting an incidence between 6 and 60%. In approximately 8% of patients, C-5 nerve root dysfunction developed based on the 12 articles in which this complication was reported.

CONCLUSIONS

The literature has yet to support the purported benefits of laminoplasty. Neurological outcome and change in spinal alignment are similar after laminectomy and laminoplasty. Patients treated with laminoplasty develop progressive limitation of cervical ROM similar to that seen after laminectomy and fusion.

Treatment of multilevel cervical spondylotic myeloradiculopathy with posterior decompression and fusion with lateral mass plate fixation and local bone graft

This is a retrospective review of 32 patients with multilevel cervical myelopathy treated by laminectomy and lateral mass plate fusion. The prognosis of surgically treated myelopathy is evaluated as well as prognostic factors for recovery of myelopathy. Diagnoses included cervical spondylosis or ossification of the posterior longitudinal ligament. Final follow-up was at 15.2 months (mean) postoperatively. Myelopathy was graded preoperatively and postoperatively by the system of Nurick. All patients had preoperative radiographs and magnetic resonance imaging (MRI). The presence of abnormal T2-weighted MRI signal (myelomalacia) was noted. Postoperative studies included flexion-extension radiographs to assess fusion and MRI to evaluate decompression of neural elements and resolution of myelomalacia. Severity of preoperative Nurick myelopathy, presence of myelomalacia, and age were evaluated as potential prognostic indicators for surgically treated myelopathy. Mean Nurick score improved from 2.6 (range 1-4) to 1.8 (range 0-3) postoperatively (p < 0.0001). Twenty-two patients (71%) had improvement in Nurick grade of at least one point, and nine showed no improvement. No patients had deterioration of Nurick grade. Preoperative myelomalacia was noted in 15 (47%) patients, and all 15 had residual myelomalacia postoperatively. Severe myelopathy, age, and myelomalacia had no prognostic value for improvement of myelopathy. Complications included pseudarthrosis (3%), wound infection (9%), and transient C5 palsy (6%). This study demonstrates excellent outcomes from laminectomy and fusion in multilevel cervical myelopathy. A high rate of improvement of myelopathy was observed, neurologic deterioration did not occur, and complication rates were low. Severe myelopathy and myelomalacia on preoperative MRI had no prognostic value.

Multilevel subtotal corpectomy and interbody fusion using a fibular bone graft for cervical myelopathy due to ossification of the posterior longitudinal ligament

A retrospective study of the outcomes of multilevel anterior decompression and interbody fusion for cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL) was performed to both investigate the long-term results and assess the cause of late deterioration. Twenty-seven patients (mean age, 58.1 years) underwent this procedure and were followed for at least 5 years. The severity of the clinical symptoms was described using the scoring system for cervical myelopathy proposed by the Japanese Orthopaedic Association (JOA score). The average preoperative JOA score was 7.7, and the score at final follow-up was 13.4 with a recovery rate of 62.0%. A delayed deterioration was attributed to a thoracolumbar lesion other than a compromising alteration of the cervical spine. Consequently, this method of treatment for OPLL could stop the progress of ossification and keep a physiological cervical alignment and thus provide good long-term results.

Complications of multilevel cervical corpectomies and reconstruction with titanium cages and anterior plating

The ideal surgical treatment of multilevel cervical spondylosis remains unclear. This study analyzed the complications in using titanium cages and plating to reconstruct multilevel cervical corpectomies. This was a retrospective analysis of 21 consecutive patients who had multilevel cervical corpectomies and reconstruction with titanium cages and anterior plating. Sixteen had 2-level, one had 2.5-level, three had 3-level, and one had 3.5-level corpectomies. All had reconstruction with titanium cages and anterior plating. Thirty-three percent of the patients developed complications. Radiographs revealed bony consolidation in 95% of patients. Reconstructing multilevel cervical corpectomies with titanium cages and plating is associated with complications. Advantages include rigid immobilization and the avoidance of iliac crest bone graft harvesting. Major complications are largely the result of failures of the cage and plate construct, especially in patients with osteopenic bone. Supplemental posterior stabilization may be considered for cases with spasticity or greater than 2-level corpectomies with profound osteoporosis.

Minimally invasive cervical expansile laminoplasty: an initial cadaveric study

OBJECTIVE

Expansile laminoplasty has been successfully used to treat cervical myelopathy attributable to canal stenosis. However, detachment of the posterior cervical muscles is thought to contribute to postoperative axial neck pain and kyphosis. Minimizing the amount of muscular dissection might reduce the likelihood of these sequelae.

METHODS

Six human cadaveric spines were used to assess the feasibility of a minimally invasive laminoplasty technique. A 22-mm tubular dilator port was used to access the lamina-facet junctions from C2 to C7, through bilateral stab incisions at C4-C5 and C5-C6. Troughs at the lamina-facet junctions were drilled bilaterally, and the contiguous laminae were lifted en bloc from one side. Ten-millimeter rib allograft spacers were inserted to maintain a gap on the open side.

RESULTS

Exposure of six cervical levels was easily accomplished with two small incisions on each side. Drilling was achieved without dural violations. The midsagittal spinal canal diameter was increased by a mean of 38% and the spinal canal area was increased by an average of 43% at the level of C5.

CONCLUSION

A minimally invasive approach for cervical laminoplasty could be performed in human cadavers. The measured increases in spinal canal space approximated those demonstrated to be associated with stabilization or improvement of neurological status.

Techniques in cervical laminoplasty

BACKGROUND CONTEXT

Laminoplasty provides an alternative to anterior procedures or multilevel laminectomy for patients with multilevel spinal stenosis and myeloradiculopathy.

PURPOSE

To review the techniques, results and complications of cervical laminoplasty.

STUDY DESIGN

The three basic variations of laminoplasty are the single open door, the French door or midline and the Z-plasty technique. These techniques and their outcome are discussed in detail.

RESULTS

The recovery rate after laminoplasty ranges from 50% to 70% without statistical superiority of any one technique over another. Closure of opened laminae, temporary nerve root deficit, decreased neck range of motion and axial pain are the main complications of laminoplasty.

CONCLUSIONS

Good to excellent long-term clinical results can be expected for the appropriately selected patients regardless of the specific technique used.

Segmental motor paralysis after expansive open-door laminoplasty

STUDY DESIGN

A retrospective study was conducted to investigate patients in whom segmental motor paralysis developed after expansive open-door laminoplasty for cervical myelopathy.

OBJECTIVE

To propose the involvement of the spinal cord as a possible mechanism in the development of segmental motor paralysis.

SUMMARY OF BACKGROUND DATA

Segmental motor paralysis is seen occasionally in patients who undergo expansive open-door laminoplasty for cervical myelopathy, and has long been attributed to nerve root lesions caused by either traumatic surgical techniques or a tethering effect induced by excessive posterior shift of the spinal cord after decompression. Involvement of spinal cord pathology is not suggested in the English literature.

METHODS

The study group consisted of 15 patients (11 men and 4 women) in whom postoperative segmental motor paralysis developed after expansive open-door laminoplasty during a minimum follow-up of 2 years. Their average age at the time of surgery was 56 years. Characteristics of the paralysis, clinical symptoms, recovery rates calculated using pre- and postoperative Japanese Orthopedic Association scores, and radiographic findings including pre- and postoperative magnetic resonance images were analyzed retrospectively and compared with those of 126 patients without segmental paralysis who underwent expansive open-door laminoplasty.

RESULTS

The paralysis occurred mainly, but not only, at C5, and eight patients had multilevel involvements predominantly in the hinge side, whereas two patients had paralysis on both sides. The paralysis had developed after an average of 4.6 days. Of the 15 patients, 14 reported severe numbness or dysesthesia in their hands before surgery, and their average recovery rate for upper extremity sensory disturbance was lower than for those without paralysis. Postoperative magnetic resonance imaging showed the presence of a T2 high-signal intensity zone in the spinal cord of all the patients. The level of such abnormal signal areas corresponded to the level of paralyzed segments in 10 of the 15 patients. Paralysis resolved completely in 11 patients.

CONCLUSIONS

Delayed onset of paralysis, dysesthesiain the upper extremities, and the presence of T2 high-signal intensity zones suggest that a certain impairment in the gray matter of the spinal cord may play an important role in the development of postoperative segmental motor paralysis.