Cervical amyotrophy caused by hypertrophy of the posterior longitudinal ligament

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.

Evidence that impaired motor conduction in the bilateral ulnar and tibial nerves underlies cervical spondylotic amyotrophy in patients with unilateral deltoid muscle atrophy

Introduction

The clinical entity of cervical spondylotic amyotrophy (CSA) is characterized by severe muscle atrophy in the upper extremities with insignificant sensory deficits in patients with cervical spondylosis. However, the pathogenesis of CSA is still unclear.

Methods

We assessed electrophysiological motor conduction through the corticospinal tract and ulnar and tibial nerves, which do not supply the deltoid or biceps muscles, of 18 patients with CSA, 12 patients with compressive cervical myelopathy, and 18 control subjects with cervical spondylotic radiculopathy. Motor evoked potentials following transcranial magnetic stimulation and M-waves and F-waves following electrical stimulation were measured from the bilateral abductor digiti minimi muscles (ADMs) and abductor hallucis muscles (AHs). The peripheral conduction time (PCT) was calculated from the latencies of the CMAPs and F-waves as follows: (latency of CMAPs + latency of F-waves - 1) / 2. The central motor conduction time (CMCT) was calculated by subtracting the PCT from the onset latency of the MEPs.

Results

The M-wave (M) latency and minimum F-wave (Fmin) latency from the ADM, and Fmin-M latency from the ADM/AH were significantly longer in the CSA group than in the other groups, on both the affected (p = 0.000-0.007) and unaffected sides (p = 0.000-0.033). F-wave persistence from the bilateral ADMs was significantly lower in the CSA group than in the other groups (p = 0.000-0.002). Among the CSA patients, there were no significant differences in these parameters between the affected and unaffected sides. The CMCT showed no significant differences between the CSA and control groups, but significant differences between the CSA and CCM groups (p = 0.000-0.004).

Conclusions

CSA patients with unilateral deltoid muscle atrophy had subclinical impairments of lower motor neurons and/or peripheral axons in the ulnar nerve, and subclinical impairments of peripheral axons in the tibial nerve. These motor impairments may have originally existed in these individuals before the onset of CSA.

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.

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.

Anterior and posterior decompressive surgery for progressive amyotrophy associated with cervical spondylosis: a retrospective study of 51 patients

Object

The aims of this study were to review the clinicoradiological findings in patients who underwent decompressive surgery for proximal and distal types of muscle atrophy caused by cervical spondylosis and to discuss the outcome and techniques of surgical intervention.

Methods

Fifty-one patients (43 men and 8 women) with proximal (37, with arm drop) and distal muscle atrophy (14, with wrist drop) underwent cervical decompression (39 anterior decompressions and 12 open-door C3–7 laminoplasties with microsurgical foraminotomy) for muscle weakness in the upper extremities. The clinical course, type of spinal cord compression, abnormal signal intensity on high-resolution MR imaging, and postdecompression improvement in muscle power were reviewed at a mean follow-up of 2.6 years (range 0.8–9.4 years).

Results

The most commonly affected vertebrae were C4–5 and C5–6, and C5–6 and C6–7 in patients with proximal or distal muscle atrophy, respectively; the respective numbers of affected vertebrae were 1.5 and 2.2. Transaxial MR imaging showed medial compression of the spinal cord in 20 patients (in 12 with proximal and 8 with distal muscle atrophy), paramedial compression in 22 (17 and 5 patients, respectively), and foraminal compression in 9 (8 and 1 patient, respectively). Increased signal intensity on MR imaging was observed in 85.0, 22.7, and 11.1% of cases of medial, paramedial, and foraminal compression, respectively. Increased signal intensity at the affected muscle segment level was observed in 52.9, 40.0, and 0% of cases, respectively. Sixty-two percent of patients with proximal muscle atrophy gained 1 or more grades of muscle power on manual muscle testing (MMT), whereas 64.3% with distal muscle atrophy failed to gain even 1 grade of improvement. The recovery of muscle power correlated with disease duration and the percent voltage of Erb point or wrist-stimulated muscle evoked potentials but not with preoperative MMT, longitudinal range of spinal cord compression, signal change on T2-weighted MR imaging, or surgical procedure.

Conclusions

Surgical outcome in patients with distal muscle atrophy was inferior to that in patients with proximal atrophy. The distal type was characterized by a long preoperative period, a greater number of cervical spine misalignments, a narrow spinal canal, and increased signal intensity on T2-weighted MR imaging. It is essential to perform a careful neurological evaluation, including sensory examination of the lower limbs, as well as neuroradiological and neurophysiological assessments to avoid confusion with motor neuron disease and to detect the coexistence of amyotrophic lateral sclerosis, especially when surgical treatment of cervical spondylosis is planned. The results of careful physical examination, MR imaging studies, and electromyography studies should be comprehensively evaluated to ascertain the pathophysiology of the muscle atrophy. It is very important to distinguish the pathophysiology caused by nerve root impingements from anterior horn dysfunction when making decisions about treatment strategy. Surgical treatment—with or without foraminotomy—for amyotrophy in cervical spondylosis requires urgent action with regard to human neuroanatomy and neural innervation of the paralyzed muscles.

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.