Evaluation of characteristics and surgical outcomes in cervical spondylotic amyotrophy

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.

Evaluation of Anterior Decompression Surgical Outcomes of Proximal-Type Cervical Spondylotic Amyotrophy: A Retrospective Study

OBJECTIVE

To investigate the efficiency of anterior decompression on the proximal-type cervical spondylotic amyotrophy patients.

METHODS

This was a retrospective analysis. From January 2014 to November 2017, 21 patients with proximal-type cervical spondylotic amyotrophy (CSA) underwent anterior decompression. There were 15 males and 6 females, aged 35-73 years with an average of 51.62 years. All the patients underwent surgery of anterior decompression (ACDF or ACCF). Among them, 12 patients underwent C_4/5 single level ACDF, eight patients underwent C_4/5 and C_5/6 double level ACDF, and one patient underwent C5 anterior cervical corpectomy decompression and fusion surgery. Preoperative and postoperative clinical and radiologic parameters were assessed. The clinical examinations were reviewed, including muscle strength, neck disability index (NDI) score, cervical Japanese Orthopaedic Association (JOA) score, and improvement rate of manual muscle test (MMT) at the last follow-up. Preoperative spinal cord or nerve impingement was assessed by magnetic resonance imaging (MRI) or computed tomography (CT) myelography. Postoperative lateral X-ray radiographs were performed every 3 months after the surgery.

RESULTS

Severe preoperative muscle atrophy of the deltoid or biceps muscles occurred in 21 patients included in the study. All of them involve impingements of the ventral nerve root and/or the anterior horn according to MRI and CT myelography. The preoperative duration of symptoms averaged 8.4 months. The average follow-up for all patients was 13.2 months. At the final follow-up, all patients showed statistically significant improvements in muscle strength and NDI scores (P < 0.05, P < 0.05). For the deltoid muscles force and C-JOA scores, the average improvement rates were 66.49% ± 10.04% and 62.23% ± 9.23%, respectively. With respect to MMT, 12 proximal-type patients were graded excellent, six were good, and three were fair, and the overall improvement rate was 85.7%.

CONCLUSIONS

For proximal-type CSA patients with cervical radiculopathy, earlier anterior decompression surgery can achieve satisfactory results by significantly improving a patient's muscle strength and relieving compression symptoms.

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.

C5 pure motor spinal cord injury: A case with a rare manifestation of cervical spinal cord injury

We report an extremely rare case showing a fifth cervical spine (C5) level pure motor cervical spinal cord injury (SCI). A 55-year-old-man lost consciousness and fell into a bathtub. Immediately after regaining consciousness, the patient had right arm drop alone. He was referred to our department for investigation of right arm drop 4 months later. Neurological examination revealed motor weakness of the right deltoid muscle. MRI of the cervical spine revealed a C3-4 level central disc herniation compressing the spinal cord. An electromyogram study revealed bilateral neurogenic discharges in the deltoid, supraspinatus and infraspinatus muscles. We diagnosed a C5 segmental pure motor SCI. We chose conservative therapy for the present patient. At the latest follow-up visit, the patient showed modest recovery of motor weakness. Although it is unusual, this case illustrates the possibility that C5 segmental pure motor palsy can occur as one of the manifestations of cervical SCI.

Clinical Features and Long-Term Surgical Outcomes of Patients with Cervical Spondylotic Amyotrophy

BACKGROUND

Cervical spondylotic amyotrophy (CSA) is not common. The clinical features and long-term surgical outcomes of patients with CSA are also unclear. We sought to summarize clinical features, assess long-term surgical outcomes, and determine the prognostic factors relevant for patients with CSA.

METHODS

A total of 136 patients with CSA who underwent anterior or posterior decompression during January 2001 to December 2012 were included. Their clinical and radiologic data were collected. The surgical outcome was evaluated using manual muscle test and improvements in the muscle strength. Correlations between the surgical outcome and various factors also were analyzed.

RESULTS

In total, 128 patients underwent anterior decompression and 8 patients underwent posterior decompression. At the final follow-up, the surgical outcome was significantly better after anterior decompression compared with that after posterior decompression. Statistical analyses showed the type of CSA, duration of symptoms, and association with ossification of the posterior longitudinal ligament were associated with a poor outcome after anterior surgery (P < 0.05).

CONCLUSIONS

Besides significant muscular atrophy in one upper extremity, CSA also occasionally presents with mild atrophy in the other upper extremity, sensory disturbance in the upper extremities, or hyperflexia in the lower extremities. Anterior decompression is generally effective in the treatment of patients with CSA. Preoperative duration of symptoms, type of CSA, and ossification of the posterior longitudinal ligament are important predictors for the surgical outcome.

Repetitive nerve stimulation as a diagnostic aid for distinguishing cervical spondylotic amyotrophy from amyotrophic lateral sclerosis

PURPOSE

To identify and compare the features of compound muscle action potential (CMAP) decrements in repetitive nerve stimulation (RNS) in patients with cervical spondylotic amyotrophy (CSA) and in patients with amyotrophic lateral sclerosis (ALS).

METHODS

The cohort consisted of 43 CSA (distal-type to proximal-type ratio: 27-16) and 35 ALS patients. Five muscles, including abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps brachii (BB), middle deltoid (Del), and upper trapezius (Trap), were tested by 3-Hz RNS. Decrements greater than cutoff values (APB > 5.8%; ADM > 4.8%; BB > 5.2%; Del > 6%; Trap > 5.1%) determined using receiver operating characteristic (ROC) curves were defined as abnormal, and the conventional criterion (≥10%) was also considered.

RESULTS

A significant CMAP decrement (>cutoff values) was recorded from at least one tested muscle in 91.4% of ALS patients, and was most common in the proximal muscle, a finding that differed significantly from CSA patients (32.6%, P < 0.05). The application of cutoff values greatly improved the sensitivity of RNS over the conventional criterion (≥10%) for the detection of ALS (P < 0.05). The specificity of this technique remained higher when performing RNS in the proximal muscles, especially in the upper trapezius (AUC = 0.864, sensitivity = 0.643, and specificity = 1.000). The decrement percentages were significantly greater in the proximal muscles of ALS patients than in those of the CSA patients (P < 0.05). In addition, illness duration was not correlated with decrement percentage in either patient group, and no difference in the frequency of decrement among different ALS diagnostic categories was observed (P > 0.05).

CONCLUSIONS

The application of RNS, especially in proximal muscles, may provide a simple accurate and noninvasive supplementary test for distinguishing CSA from ALS, even in the early stage of these diseases. A combination of RNS, needle EMG, clinical features and cervical magnetic resonance imaging may yield sufficient diagnostic information to differentiate CSA and ALS.