Ossification of the posterior longitudinal ligament--a roentgenologic and clinical investigation

Neurological complications of ankylosing spondylitis: neurophysiological assessment

Studies examined the neurological involvement of ankylosing spondylitis (AS) are limited. This study aimed to assess the frequency of myelopathy, radiculopathy and myopathy in AS correlating them to the clinical, radiological and laboratory parameters. Included were 24 patients with AS. Axial status was assessed using bath ankylosing spondylitis metrology index (BASMI). Patients underwent (a) standard cervical and lumbar spine and sacroiliac joint radiography, (b) somatosensory (SSEP) and magnetic motor (MEP) evoked potentials of upper and lower limbs, (c) electromyography (EMG) of trapezius and supraspinatus muscles. Patients' mean age and duration of illness were 36 and 5.99 years. Bath ankylosing spondylitis metrology index mean score was 4.6. Twenty-five percent (n = 6) of patients had neurological manifestations, 8.3% of them had myelopathy and 16.7% had radiculopathy. Ossification of the posterior (OPLL) and anterior (OALL) longitudinal ligaments were found in 8.3% (n = 2) and 4.2% (n = 1). About 70.8% (n = 17) had >or=1 neurophysiological test abnormalities. Twelve patients (50%) had SSEP abnormalities, seven had prolonged central conduction time (CCT) of median and/or ulnar nerves suggesting cervical myelopathy. Six had delayed peripheral or root latencies at Erb's or interpeak latency (Erb's-C5) suggesting radiculopathy. Motor evoked potentials was abnormal in 54% (n = 13). Twelve (50%) and five (20.8%) patients had abnormal MEP of upper limbs and lower limbs, respectively. About 50% (n = 12) had myopathic features of trapezius and supraspinatus muscles. Only 8.3% (n = 2) had neuropathic features. We concluded that subclinical neurological complications are frequent in AS compared to clinically manifest complications. Somatosensory evoked potential and MEP are useful to identify AS patients prone to develop neurological complications.

Neuropathic bladder dysfunction in patients with ossification of the posterior longitudinal ligament

BACKGROUND

Ossification of the posterior longitudinal ligament (OPLL) may cause neuropathic bladder dysfunction due to spinal cord involvement. OPLL, unlike a traumatic spinal cord lesion, progresses insidiously and sometimes affects longer cord segments. As the manifestation of bladder dysfunction may depend on the development of OPLL, we studied the relationship between bladder function and roentgenographic changes in the spinal canals of OPLL patients.

PATIENTS AND METHODS

Eighteen surgical candidates (11 males and 7 females, 34 to 85 years old) were studied urodynamically. Sixteen underwent CO2-filling cystometry, uroflowmetry and measurement of their residual urine volume. Cystometry was omitted in the remaining 2 patients. The vertical extent of OPLL and the degree of stenosis in the spinal canal was estimated by x-ray films and CT.

RESULTS

The cystometric study revealed detrusor hyperreflexia in 2 patients and areflexic or underactive detrusors in 5 patients. Intermittent flows or considerable amounts of residual urine were also observed in the arefilexia/underactive group. Uroflowmetry showed a normal flow with little residual urine in both patients in whom cystometry was omitted. Bladder sensation was maintained in all patients. The occurrence of abnormal detrusor activity had no relationship to the degree of canal stenosis, while the occurrence of an areflexic or underactive detrusor correlated with the vertical extent of OPLL.

CONCLUSION

Although detrusor hyperreflexia is common in an upper spinal cord lesion, attention should also be paid to the development of detrusor underactivity in patients with a wide vertical extent of OPLL.

Ossification of the posterior longitudinal ligament in three geographically and genetically different populations of ankylosing spondylitis and other spondyloarthropathies

STUDY DESIGN

Cross sectional.

RESEARCH QUESTIONS

(a) Is any clinical variable of ankylosing spondylitis (AS) associated with the presence of ossification of the posterior longitudinal ligament (OPLL)? and (b) Is OPLL present in patients with AS from different geographical or genetic backgrounds?

METHODS

Three groups were assembled: (1) a prospective group of 103 consecutive AS patients from two community based rheumatology clinics from Guadalajara, who were evaluated using: a questionnaire with disease characteristics variables; clinical assessment by a neurologist; lateral radiographic views of the cervical spine and somatosensory evoked potentials (SSEP). (2) Fifty one spondyloarthropathies (SpA) patients from Mexico city whose cervical spine films were retrospectively reviewed. (3) Thirty nine AS patients from Edmonton, Canada whose cervical spine films were retrospectively reviewed and compared with 72 controls.

RESULTS

Group 1: 74% of the 103 patients were men and 86% were HLA-B27 positive. The mean age was 35 years, and mean (SD) disease duration 10 (8) years. OPLL was reported in 16 patients (15.5%; 95% CI 9, 22). OPLL was statistically associated with older age (p = 0.001), longer disease duration (p = 0.001), clinical myelopathy (p = 0.03), worst functional index (p = 0.042), restricted axial movement measurements (all p < 0.001), radiological sacroilitis (p < 0.001 for linear association), osteitis pubis (p = 0.009), hip involvement (p = 0.006 for linear association), and abnormal SSEP (p = 0.008). Group 2: 92% of 51 patients were men; the mean age was 30 years and the mean (SD) disease duration 11 (7) years. OPLL was reported in 15 (29%, 95% CI 17, 41) patients (nine AS, two psoriatic arthritis, three juvenile AS, and one Reiter's syndrome). Group 3: 95% of the 39 patients were men; the mean of age was 46 years and disease duration of 18 (10) years. OPLL was reported in nine (23%; 95% CI 10, 36) patients, including one with psoriatic arthritis, and two with Crohn's disease. OPLL was observed in two of the control group.

CONCLUSIONS

The prevalence of OPLL in AS and SpA is higher than previously recognised and seems to be associated with variables identifying more severe axial disease.

Ossification of posterior longitudinal ligaments: evaluation with MRI

Ossification of the posterior longitudinal ligament is a special subcategory of degenerative disease responsible for compression of the spinal cord. On MR images, T2-weighted sequences are the most effective to evaluate both spinal cord compression due to the ossification and abnormal signal intensity of the cord. Although ossification of the ligaments is well demonstrated on CT and plain radiographs, MRI noninvasively provides useful information about the degree and extent of spinal cord compression, as well as the character of the ossification.

Cervical spine stenosis secondary to ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) is a well-documented cause of cervical spine stenosis and myelopathy among Japanese patients. Reports of OPLL in North Americans are rare. Choices of diagnostic method and treatment for this entity remain controversial. The authors report the results of management of 20 patients in the United States with symptomatic OPLL of the cervical spine. These represented 10% to 20% of patients operated on over the last 3 years for myelopathy secondary to structural spinal compression. Most of these OPLL patients were Caucasian (60%), male (male:female 4:1), and middle-aged (median age 47.5 years). Six had previously undergone laminectomy or discectomy. Cervical roentgenograms and standard myelography occasionally suggested the diagnosis. Axial computerized tomography (CT) metrizamide myelography with small interslice intervals proved invaluable for diagnosis and operative planning. Magnetic resonance imaging was not necessary for diagnosis. Retrovertebral calcification extended over one to five bodies (mean 2.75). The mass ranged in size from 5 to 16 mm in anteroposterior diameter and reduced the residual canal diameter to a mean (+/- standard deviation) caliber of 9.42 +/- 2.41 mm (mean narrowing ratio 0.44 +/- 0.12). Anterior cervical decompression by medial corpectomy and discectomy with fusion uniformly reduced preoperative myelopathy. Complications were limited to transient neurological deterioration in two patients, recurrent laryngeal nerve palsy in one, and halo device pin site infections in two. At a mean postoperative interval of 15 months, improvement was seen in each category of deficit: extremity weakness, hypesthesia, hypertonia, and urinary dysfunction. All fusions produced solid unions. It is concluded that OPLL of the cervical spine is an unexpectedly prevalent cause of myelopathy among patients treated in the United States. Thin-section axial CT metrizamide myelography with small interslice intervals is essential for the investigation of patients who may have OPLL. Anterior decompression and stabilization by medial corpectomy, discectomy, removal of the calcified mass, and fusion is a safe and effective method of treatment.