Cervical Spondylotic Amyotrophy Treated by Anterior Decompression-Three Case Reports-

A Case of Cervical Spondylotic Amyotrophy Mimicking Amyotrophic Lateral Sclerosis

Cervical spondylotic amyotrophy (CSA) is a rare clinical condition characterized by weakness and atrophy of the upper limb with minimal to no associated sensory deficits. The detection of the disease is based on clinical features at presentation, neurological examination, electrophysiological studies, and imaging. The proposed pathophysiological mechanisms include selective damage to the ventral root or anterior horn cells of the spinal cord. Depending on the muscle groups that are involved, CSA is broadly classified into a proximal type and a distal type. The clinical profiles of patients with CSA and ALS have a very close resemblance to each other, especially at the early stages of the disease. Cervical spine magnetic resonance imaging (MRI) may show T2 hyperintensity in both proximal and distal types. Electromyogram demonstrates denervation potentials and reduced motor unit potentials in the affected muscles. The conservative management is often the first-line modality, and those who fail to respond to conservative treatment have severe muscular atrophy and weakness, and distal-type CSA are considered potential candidates for surgery. We present the case of a 57-year-old female who presented with a 1-year history of left-hand weakness and wasting with no sensory deficits. She denied any involvement of her other hand or bilateral lower limbs, and she was referred to our clinic with the potential diagnosis of amyotrophic lateral sclerosis (ALS). An elaborate history, physical examination, electrophysiological studies, and imaging assisted us in reaching the diagnosis of CSA, 1 year after the onset of symptoms.

Cervical Spondylotic Amyotrophy: Case Series and Review of the Literature

OBJECTIVE

Cervical spondylotic amyotrophy (CSA) is a relatively rare entity caused by cervical degenerative spinal diseases and characterized by motor weakness accompanied by remarkable muscle atrophy in the upper extremities without significant sensory deficits or spastic paraparesis in the lower extremities. Postoperative outcomes and predictive prognostic factors vary among previous reports. In the present report, we describe the surgical results in patients who were surgically treated for CSA and present a literature review.

METHODS

In total, 33 patients with CSA were retrospectively analyzed. Correlations between the surgical outcome and the following factors were statistically analyzed: age, sex, type of impaired muscle, preoperative severity of motor weakness, number of levels of cord or root compression, presence of a T2 high-intensity area in the spinal cord, cervical kyphosis, and methods of surgical procedure.

RESULTS

On postoperative neurological evaluation, 25 patients (75.8%) had favorable outcomes and 8 had unfavorable outcomes (proximal type, 72.2%; distal type, 78.6%). Patients with favorable outcomes were significantly younger than those with unfavorable outcomes (p=0.013). Patient's characteristics except for age and radiological factors were not correlated to surgical outcome.

CONCLUSION

The present study focused on the surgical results in patients who were surgically treated for CSA along with updated information from a literature review. Improvement of motor weakness is expected with acceptable prevalence although higher age can be a negative factor. Surgical outcomes and predictive factors related to a poor prognosis were determined and compared with those of previous articles.

Surgical outcomes for distal-type cervical spondylotic amyotrophy: a multicenter retrospective analysis of 43 cases

PURPOSE

Distal-type cervical spondylotic amyotrophy (CSA) is a rare form of cervical spondylosis that causes muscle weakness of upper extremities. The pathophysiology and appropriate surgical method for the treatment of CSA are still controversial. We investigated clinical outcomes in surgically treated distal-type CSA.

METHODS

The authors executed an analysis of the outcomes of 43 consecutive spinal surgeries performed in distal-type CSA patients. The duration of symptoms, perioperative manual muscle test (MMT) results, radiological findings, and perioperative complications were reviewed. We compared surgical outcomes between different approaches and examined the factors related to poor outcomes (MMT improvement ≤ 0) after surgery.

RESULTS

The pathophysiology of CSA was mostly caused by a combination of multiple lesions in the anterior horn and/or nerve root. Nineteen of 29 patients (65.5%) who received anterior approach methods were included in the good outcome group (MMT improvement ≥ 1), whereas 7 of 14 patients (50.0%) in the posterior group were classified as good. In the anterior group, the mean MMT grade significantly improved from 2.6 to 3.4 (p = 0.0035) despite the higher rate of complications. The duration of symptoms was substantially associated with poor outcomes. The MMT grade significantly improved from 2.2 to 3.2 (p = 0.0118) in the < 6 months group. Cervical alignments and preoperative MMT grade were not statistically associated with poor outcomes.

CONCLUSIONS

Patients with poor outcomes had symptoms for a longer duration. We found tolerable clinical outcomes within 6 months from onset. The anterior approaches might be recommended because this procedure significantly improved MMT levels in the hands. These slides can be retrieved under Electronic Supplementary Material.

Cervical spondylotic amyotrophy: a systematic review

PURPOSE

Cervical spondylotic amyotrophy (CSA) is characterized by upper limb muscle weakness and atrophy, without sensory deficits. The pathophysiology of CSA has been attributed to selective injury to the ventral nerve root and/or anterior horn of the spinal cord. This review aimed to delineate the history of CSA and to describe the epidemiology, etiology, pathophysiology, classification, clinical features, radiological and electrophysiological assessment, diagnosis, differential diagnosis, natural history and treatment of CSA.

METHODS

A comprehensive search of PubMed, EMBASE, Cochrane library and Web of Science databases was conducted, from their inception to April 3, 2018.

RESULTS

Clinically, CSA is classified into three types: a proximal-type (involving the scapular muscles, deltoid and biceps), a distal-type (involving the triceps and muscles of the forearm and hand) and a diffuse-type (involving features of both the distal- and proximal-type). Diagnosis requires documentation of muscle atrophy, without significant sensory deficits, supported by careful neurological, radiological and neurophysiological assessments, with amyotrophic lateral sclerosis, Parsonage-Turner syndrome, rotator cuff tear and Hirayama disease being the principle differential diagnoses. Conservative management of CSA includes cervical traction, neck immobilization and physical therapy, with vitamin B12 or E administration being useful in some patients. Surgical treatment, including anterior decompression and fusion or laminoplasty, with or without foraminotomy, is indicated after conservative treatment failure. Factors associated with a poor outcome include the distal-type CSA, long symptom duration, older age and greater preoperative muscle weakness.

CONCLUSION

Although the disease process of CSA is self-limited, treatment remains challenging, leaving scope for future studies. These slides can be retrieved under Electronic Supplementary Material.

Pattern Differences of Small Hand Muscle Atrophy in Amyotrophic Lateral Sclerosis and Mimic Disorders

Background:

Amyotrophic lateral sclerosis (ALS) and some mimic disorders, such as distal-type cervical spondylotic amyotrophy (CSA), Hirayama disease (HD), and spinobulbar muscular atrophy (SBMA) may present with intrinsic hand muscle atrophy. This study aimed to investigate different patterns of small hand muscle involvement in ALS and some mimic disorders.

Methods:

We compared the abductor digiti minimi/abductor pollicis brevis (ADM/APB) compound muscle action potential (CMAP) ratios between 200 ALS patients, 95 patients with distal-type CSA, 88 HD patients, 43 SBMA patients, and 150 normal controls.

Results:

The ADM/APB CMAP amplitude ratio was significantly higher in the ALS patients (P < 0.001) than that in the normal controls. The ADM/APB CMAP amplitude ratio was significantly reduced in the patients with distal-type CSA (P < 0.001) and the HD patients (P < 0.001) compared with that in the normal controls. The patients with distal-type CSA had significantly lower APB CMAP amplitude than the HD patients (P = 0.004). The ADM/APB CMAP amplitude ratio was significantly lower in the HD patients (P < 0.001) than that in the patients with distal-type CSA. The ADM/APB CMAP amplitude ratio of the SBMA patients was similar to that of the normal controls (P = 0.862). An absent APB CMAP and an abnormally high ADM/APB CMAP amplitude ratio (≥4.5) were observed exclusively in the ALS patients.

Conclusions:

The different patterns of small hand muscle atrophy between the ALS patients and the patients with mimic disorders presumably reflect distinct pathophysiological mechanisms underlying different disorders, and may aid in distinguishing between ALS and mimic disorders.

Predisposing factors for poor outcome of surgery for cervical spondylotic amyotrophy: a multivariate analysis

The purpose of this study was to characterize risk factors for poor surgical outcome in patients with cervical spondylotic amyotrophy (CSA). We retrospectively reviewed 88 cases of CSA surgery and investigated age, sex, duration of symptoms, atrophy type, preoperative muscle power, signal changes on MRI, anterior horn (AH) or ventral nerve root (VNR) compression, compression levels, surgical approach and postoperative recovery. Fifty (56.8%) patients had good surgical outcome. Logistic regression, with poor outcome as dependent variable, showed independent risks associated with duration of symptoms (OR; 1 for symptom duration less than 3 months versus 3.961 [95% CI; 1.203–13.039, p = 0.024] for symptom duration of 3–6 months versus 18.724 [95% CI; 3.967–88.367, p < 0.001] for symptom duration greater than 6 months), compression type (OR; 1 for VNR versus 4.931 [95% CI; 1.457–16.685, p = 0.010] for AH versus 5.538 [95% CI; 1.170–26.218, p = 0.031] for VNR + AH), and atrophy type (OR; 1 for proximal type versus 6.456 [95% CI; 1.938–21.508, p = 0.002] for distal type). These findings suggest that a long duration of symptoms, AH or both AH and VNR compression, and distal type are risk factors for poor surgical outcome in patients with CSA.

Reconstruction of shoulder and elbow function using multiple muscle transfers for cervical spondylotic amyotrophy

STUDY DESIGN

This was a retrospective study of 8 patients with cervical spondylotic amyotrophy who underwent multiple muscle transfers.

OBJECTIVE

The purpose of this study was to evaluate results of multiple muscle transfers about the shoulder and elbow in patients with cervical spondylotic amyotrophy.

SUMMARY OF BACKGROUND DATA

Cervical spondylotic amyotrophy is characterized by severe muscle atrophy of the shoulder girdle and elbow. Even after cervical spine surgery, many patients have poor shoulder and elbow function.

METHODS

Multiple muscle transfer procedures including the transfer of trapezius, pectoralis major, latissimus dorsi muscles, and the Steindler procedure for reconstruction of shoulder and elbow function were performed in 8 patients with cervical spondylotic amyotrophy. Patients were evaluated at a mean of 18.2 months (range, 5-75 mo).

RESULTS

All 8 patients obtained satisfactory functional recovery with improvement of active range of motion without any systemic and local complications within 3 to 6 months postoperatively. Patients at the last follow-up had obtained a mean of 91° of shoulder abduction, 111° of shoulder flexion, 23° of external rotation and 110° of elbow flexion. Disability scores (Japanese version) of the arm, shoulder, and hand improved by a mean of 28 points.

CONCLUSION

Multiple muscle transfers can improve shoulder and elbow function in cervical spondylotic amyotrophy, in cases of not only poor outcome after cervical surgery, but also in advanced paralysis. It is a useful set of procedures even in old patients, and provides definitive functional improvement of shoulder and elbow function from 3 to 6 months.

LEVEL OF EVIDENCE

4.

Anterior decompression in the management of unilateral cervical spondylotic amyotrophy

Cervical spondylotic amyotrophy is a rare clinical condition. The purpose of this study was to investigate the effects of anterior decompression in patients with unilateral upper-extremity amyotrophy caused by cervical spondylosis. The authors retrospectively analyzed the records of 31 patients (23 men and 8 women) who underwent anterior decompressive surgery for cervical spondylotic amyotrophy at the authors' institution between 2000 and 2011. Demographic characteristics, pre- and postoperative results of imaging studies, and postoperative muscle power improvement were reviewed at a mean follow-up of 22.2 months (range, 14-36 months). Patients were divided into proximal (n=21) and distal (n=10) types according to the most severely atrophic muscle, and the 2 groups were compared statistically. The most commonly affected intervertebral level in proximal-type patients was C4-C5, whereas that in distal-type patients was C5-C6. Impingements against the ventral nerve root and anterior horn were observed in 22 and 25 cases, respectively, with 16 cases having both impingements. Eighty-one percent of proximal-type patients gained 1 or more grades of muscle power improvement on manual muscle testing, whereas 40% of distal-type patients improved. Within 15 postoperative days, 57% of proximal-type patients attained subjective or objective improvement of muscle power, whereas all distal-type patients failed to improve. Anterior decompression was effective for most patients with unilateral cervical spondylotic amyotrophy, although postoperative muscle power improvement in distal-type patients was inferior to that in proximal-type patients. Furthermore, compared with the proximal type, the distal type showed a slower postoperative recovery.

Prediction of surgical outcome for proximal-type cervical spondylotic amyotrophy novel mode of assessment using compound action potentials of deltoid and biceps brachii and central motor conduction time

STUDY DESIGN

Case studies of patients with cervical spondylotic amyotrophy used compound muscle action potentials (CMAPs) of deltoid and biceps brachii muscles and central motor conduction time (CMCT).

OBJECTIVE

To discuss surgical outcome for proximal-type cervical spondylotic amyotrophy in the context of results obtained with CMAPs and CMCT.

SUMMARY OF BACKGROUND DATA

There have been no reports that correlate surgical outcome with CMAPs of deltoid and biceps brachii muscles or with CMCT.

METHODS

A retrospective study was performed for 24 patients with proximal-type cervical spondylotic amyotrophy who underwent surgical treatment of the cervical spine. Erb-point-stimulated CMAPs were recorded in the deltoid and biceps. The percent amplitude of CMAPs was calculated in comparison with the opposite side. Motor-evoked potentials were recorded from bilateral abductor digiti minimi. CMAPs and F waves were recorded after supramaximal electric stimulation of ulnar nerves. CMCT was calculated as follows: motor-evoked potentials latency - (CMAPs' latency + F latency - 1)/2 (ms). Muscle strength was evaluated using manual muscle testing. Improvements in strength were classified as excellent, good, or fair.

RESULTS

The improvement was graded as excellent in 12 cases, good in 2 cases, and fair in 10 cases. The average percentage for CMAPs' amplitude on the affected side compared with the normal side in deltoid and biceps brachii muscles was significantly different between the excellent and fair patient groups. The CMCT on the affected side was not significantly different between excellent and fair patient groups.

CONCLUSION

The average percentage range of deltoid and biceps brachii muscle CMAPs' amplitude determined at the onset of illness correlated significantly with postoperative recovery. Surgical intervention of the cervical spine should be performed in patients in whom the average percentage of CMAPs' amplitude in deltoid and biceps brachii muscles ranges from 30% to 50%.

Risk factors for a poor outcome following surgical treatment of cervical spondylotic amyotrophy: a multicenter study

INTRODUCTION

Cervical spondylotic amyotrophy (CSA) is characterized by muscle atrophy in the upper extremities without gait disturbance. However, the indications and outcomes of surgical treatment for CSA have not been clarified. The purpose of this study was to determine the risk factors for a poor outcome following surgical treatment of CSA.

MATERIALS AND METHODS

We performed a retrospective review of CSA in patients from 1991 to 2010 through a multicenter study. We collected information regarding age, type of muscle atrophy, preoperative manual muscle test (MMT), duration of symptoms, high-intensity areas on T2-weighted MR images, low-intensity areas on T1-weighted MR images, levels of spinal canal stenosis, cervical kyphosis and surgical procedures (laminoplasty, anterior cervical discectomy and fusion and posterior spinal fusion), and calculated overall risk factors related to a poor outcome following surgery. Univariate analyses and multivariate logistic regression analysis were performed to identify correlates of a poor outcome.

RESULTS

Fifty-nine patients, 95 % male (56 patients), were included in our analysis with a mean age of 59 years (range 32-78 years). Eighteen patients did not improve after surgery. Symptom duration (OR = 1.263), preoperative MMT grade (OR = 0.169) and distal type of CSA (OR = 9.223) were all associated with an increased risk of a poor surgical outcome.

CONCLUSION

Early surgery is recommended for CSA patients in whom conservative treatment has not been successful. We also recommend surgery for patients who have severe preoperative muscle weakness or have the distal type of CSA.

Cervical spondylotic amyotrophy

Cervical spondylotic amyotrophy is characterized with weakness and wasting of upper limb muscles without sensory or lower limb involvement. Two different mechanisms have been proposed in the pathophysiology of cervical spondylotic amyotrophy. One is selective damage to the ventral root or the anterior horn, and the other is vascular insufficiency to the anterior horn cell. Cervical spondylotic amyotrophy is classified according to the most predominantly affected muscle groups as either proximal-type (scapular, deltoid, and biceps) or distal-type (triceps, forearm, and hand). Although cervical spondylotic amyotrophy always follows a self-limited course, it remains a great challenge for spine surgeons. Treatment of cervical spondylotic amyotrophy includes conservative and operative management. The methods of operative management for cervical spondylotic amyotrophy are still controversial. Anterior decompression and fusion or laminoplasty with or without foraminotomy is undertaken. Surgical outcomes of distal-type patients are inferior to those of proximal-type patients.

Bilaterally symmetric cervical spondylotic amyotrophy: a novel presentation and review of the literature

BACKGROUND

Cervical spondylotic amyotrophy (CSA) is considered a syndrome of (1) unilateral upper extremity weakness and atrophy, (2) affecting either the proximal or distal musculature, (3) without sensory impairment or lower extremity dysfunction.

AIMS OF STUDY

The authors report a novel case of bilaterally symmetric CSA with blurring of the proximal-distal distinction, discuss the pathophysiology, and review the literature.

METHODS

A 45 year old man presented with a several year history of insidiously progressive bilaterally symmetric upper extremity weakness and wasting, profound in the proximal musculature and moderate to severe in the distal muscle groups.

RESULTS

Based on the clinical, neuroimaging and electrodiagnostic features, this patient harbors a more severe phenotype of the classical syndrome.

CONCLUSION

The authors propose expanding the generally accepted definition of CSA to include this bilaterally symmetric form of disease, thereby minimizing diagnostic error or delay. Additionally, based on this case and a review of the literature, adherence to the proximal-distal distinction should be avoided since it is commonly blurred. Accurate diagnosis is crucial since this presentation mimics the motor neuron disease variant Vulpian-Bernhardt syndrome. The importance of early diagnosis is underscored by reports of significant improvement with timely surgical decompression.

Cervical spondylotic amyotrophy presenting as dropped head syndrome

We report a case of acute-onset dropped head syndrome in a 65-year-old patient in whom the diagnosis of amyotrophic lateral sclerosis (ALS) was initially proposed based on electromyographic signs of neck and shoulder muscle denervation. There were no signs of pyramidal involvement and the clinical and electromyographic signs of motor denervation never evolved beyond the neck and shoulder girdle muscles after a 6-year follow-up period, which argued against ALS. Other causes of dropped head syndrome were carefully ruled out based on clinical findings, electrodiagnostic studies and blood investigations. The restriction of muscle denervation to a few cervical myotomes, the presence of C3-C4 spondylotic changes without associated root or spinal cord compression, and the absence of an alternative explanation to the patient's symptoms strongly supported the diagnosis of cervical spondylotic amyotrophy (CSA). CSA is thought to result from spinal cord microcirculatory disturbances and secondary anterior horn cell degeneration due to ischemia. Our case enlarges the clinical spectrum of focal cervical anterior horn disease, which classically results in more distal monomelic atrophy affecting one or both upper limbs.

Distal-type cervical spondylotic amyotrophy: incidence and outcome after central corpectomy

OBJECT

Distal-type cervical spondylotic amyotrophy (CSA) is a rare form of cervical spondylotic myelopathy (CSM). The authors documented the incidence, clinical presentation, radiological features, and outcome following central corpectomy (CC) in patients with this entity.

METHODS

The authors performed a retrospective institutional database search of patients who underwent decompressive surgery for CSM between 1992 and 2006 to identify patients with distal-type CSA. Distal-type CSA was defined as weakness and wasting of hands and forearms without gait impairment (Nurick Grades 0 and 1) nor any sensory symptoms or signs in the lower limbs.

RESULTS

The authors identified 7 male patients (1.1%) with distal-type CSA from among 653 patients who underwent either cervical laminectomy (135 patients) or CC (518 patients). There were sensory symptoms or signs in the upper limbs in all but 1 of the patients. Increased signal intensity in the cord was demonstrated on T2-weighted MR images in all patients. The compression was mainly at the C-6 vertebral level. At a mean follow-up of 46.5 months (range 12-98 months), 6 patients had improved by a mean patient perceived outcome score of 66.7% (range 20-100%). Patients' modified Japanese Orthopedic Association scores improved from a preoperative mean (+/- SD) of 16.1 +/- 0.7, to a follow-up mean of 17.4 +/- 0.5 (p = 0.004, paired t-test). One patient whose condition worsened 7 months after CC received a diagnosis of a coexistent motor neuron disease.

CONCLUSIONS

Distal-type CSA is a rare form of CSM that should be differentiated from motor neuron disease on the basis of subtle sensory symptoms or signs in the upper limbs, and the presence of significant cord compression on the MR imaging. Patient outcome after central corpectomy is good and long lasting.