Cervical Spondylotic Amyotrophy: Case Series and Review of the Literature

Paraspinal Muscle Morphology in Proximal Cervical Spondylotic Amyotrophy

STUDY DESIGN AND OBJECTIVE

This is a retrospective analysis of prospectively collected single-center observational data. The aim is to evaluate atrophy and fatty degeneration rates of cervical spinal muscles in proximal cervical spondylotic amyotrophy (PCSA).

OVERVIEW OF LITERATURE

Proximal cervical spondylotic amyotrophy affects muscles in the upper extremities. In cases that lack improvement with conservative treatment, surgery is recommended. However, preoperative factors associated with poor outcomes remain unclear. We hypothesized that assessing fatty degeneration of the cervical spinal muscles and examining its relationship with functional impairment would help predict postoperative improvement in neurological function.

METHODS

This study included 18 patients who underwent PCSA surgery. We performed selective laminoplasty and foraminotomy. Preoperative paraspinal muscle cross-sectional area and fatty degeneration were quantified and correlated with neurological function.

RESULTS

Neurological improvement based on manual muscle testing was observed in 12/18 patients, comparing preoperative, perioperative, and over 12-month postoperative statuses. On the affected side, at the C4/5 level, fatty degeneration was more significant in the trapezius, whereas at the C5/6 level, fatty degeneration was more significant in the splenius capitis and trapezius. The fatty degeneration of the C4/5 and C5/6 trapezius was significantly correlated with preoperative muscle strength and postoperative muscle strength improvement.

CONCLUSIONS

The degree of fat infiltration of the muscle correlated with pre- and postoperative muscle strength at the lesion level. Thus, our results suggest a relationship between cervical muscle morphology and the clinical manifestations of PCSA. The marked increase in trapezius fatty infiltration at the C4/5 and C5/6 levels may be a valuable indicator to predict poor improvements in postoperative muscle strength.

Surgical Outcomes of Full Endoscopic Posterior Cervical Foraminotomy for Proximal Cervical Spondylotic Amyotrophy

STUDY DESIGN

Retrospective analysis of case series.

PURPOSE

This study aimed to clarify the effects of full endoscopic posterior cervical foraminotomy (FPCF) on cervical spondylotic amyotrophy (CSA).

OVERVIEW OF LITERATURE

The method for decompressing the ventral nerve root and anterior horn (AH) in CSA is controversial.

METHODS

Patients without myelopathy who underwent FPCF for proximal CSA between 2017 and 2022 were analyzed. The outcome measure was the results of the manual muscle testing (MMT) of the deltoid and biceps. Preoperative nerve root and AH compression were evaluated by magnetic resonance imaging. The intervertebral foramen morphology and bony decompression extent were evaluated by computed tomography.

RESULTS

FPCF was performed at the C4/5 level and at the C4/5 and C5/6 levels in 14 and 11 patients, respectively. The width of the narrowest intervertebral foramen was significantly narrower on the affected side than on the healthy side at the C4/5 (2.5 mm vs. 3.6 mm) and operated C5/6 (1.9 mm vs. 3.1 mm) levels. AH compression occurred at the C4/5 and C5/6 levels in 28% and 21% of the patients, respectively. Bony decompression was performed laterally beyond the narrowest foramen at the C4/5 and C5/6 levels in 96% and 91% of the patients, respectively. Compared with patients without AH compression, in those with AH compression, the lamina was resected medially by an average of >1.7 mm and >3.6 mm at the C4/5 and C5/6 levels, respectively. Furthermore, 76% and 81% of the facet joint surfaces were preserved at the C4/5 and C5/6 levels, respectively. Postoperative MMT grade improvement was excellent, good, and fair in 64%, 20%, and 16% of the patients, respectively.

CONCLUSIONS

FPCF was effective for treating proximal CSA.

Cervical Spondylotic Amyotrophy Initially Misdiagnosed as Amyotrophic Lateral Sclerosis

A 63-year-old man diagnosed with mixed-type cervical spondylotic amyotrophy exhibited severe atrophy in the right biceps brachii, teres major, and intrinsic hand muscles, resulting in level 3 muscle weakness. Magnetic resonance imaging showed symmetrical high signal, also referred to as the snake eye sign. Previously, he was erroneously diagnosed with amyotrophic lateral sclerosis. He had undergone anterior cervical surgery 7 years prior. At present, his right upper limb muscles display minimal atrophy compared with the left, with muscle strength nearing level 4, which is considered normal. We believe that prompt surgical intervention on diagnosis of cervical spondylotic amyotrophy, along with comprehensive postsurgery rehabilitation, can halt further deterioration of the condition and accelerate recovery.

Recent advances in neuroanatomy: the myotome update

The myotome of a muscle is the basis for diagnosing spinal and peripheral nerve disorders. Despite its critical importance in clinical neurology, myotome charts presented in many textbooks, surprisingly, show non-negligible discordances with each other. Many authors do not even clearly state the bases of their charts. Studies that have presented with raw data regarding myotome identification are rather rare. A classic study in the 19th century that pursued the nerve course in cadavers still has a substantial influence on existing charts, despite its definite limitations. Other scarce studies in humans include identification by root stimulation during surgery, clinical observations in root avulsion or spinal cord injury and clinical and electromyographical investigations in patients with single radiculopathies or certain plexopathies. A few recent studies have proposed new theories regarding the myotomes of some muscles. T1 innervation of the median intrinsic hand muscles is a typical example. We have added a number of new findings, such as T1 innervation of the forearm flexor muscles innervated by the median nerve except the pronator teres and flexor carpi radialis, C5 innervation of the brachioradialis, and two C6 indicator muscles, pronator teres and extensor carpi radialis brevis. Increased accuracy of the myotome charts will improve the localisation in neurology.

Description of Clinical Features and Diagnoses of 444 Cases with Neck-Shoulder-Upper Extremity Pain: A Single-Center Retrospective Review

PURPOSE

Neck-shoulder-upper extremity pain (NSUEP) is a frequently occurring clinical constellation of syndromes. However, its etiology is complicated, and the diagnosis is challenging. We aimed to present detailed clinical characteristics and diagnoses of NSUEP from a single center and heighten clinicians' understanding of this condition.

PATIENTS AND METHODS

Prospectively collected databases were used to retrospectively evaluate patients with NSUEP who underwent treatment at the multidisciplinary consultation center for neck, shoulder, and upper extremity pain at the China-Japan Union Hospital of Jilin University between April 2014 and July 2021. We performed descriptive statistics regarding demographic data, symptoms, findings of physical and radiographic examinations, and each patient's diagnosis.

RESULTS

Development of NSUEP was primarily observed in individuals aged between 51 and 60 years (n = 157, 35.4%). Patients were most commonly referred for upper extremity pain (n = 306, 68.9%). Patients with upper extremity pain presented with hypoesthesia (n = 139, 45.4%), muscle weakness (n = 93, 30.4%), muscle atrophy (n = 90, 29.4%), hyperesthesia (n = 39, 12.7%), and turgidity (n = 18, 5.9%). Among the 22 patients with upper extremity swelling, 8 (36.4%) were diagnosed with autoimmune rheumatic diseases. Among the 352 patients with a single diagnosis, 51 (14.5%) presented with thoracic outlet syndrome, 49 (13.9%) with cervical radiculopathy, 16 (4.5%) with carpal tunnel syndrome, and 16 (4.5%) with brachial plexus injury. Further, among the 92 patients with compound diagnosis, 18 patients (19.6%) were diagnosed with cervical radiculopathy.

CONCLUSION

Among the NSUEP patients in this study, older individuals were the largest group. Pain, numbness, weakness, and mobility limitation are common complaints accompanying NSUEP. The common etiologies of NSUEP include cervical spondylosis, thoracic outlet syndrome, carpal tunnel syndrome, and brachial plexus injury. In addition, autoimmune rheumatic diseases should be considered in patients with NSUEP and swelling.

Neuralgic Amyotrophy: Its Importance in Orthopedics Practice

The present academic work aims to contribute to an early diagnosis of neuralgic amyotrophy (NA) because of its high prevalence in the population. This disease is a neuromuscular syndrome with unclear etiology; it affects mostly the brachial plexus, causing acute pain in the affected shoulder, paralysis, and disabilities. Considering the importance of an early treatment that can modify the prognosis of the patient, knowing the last updates about the syndrome as its clinical presentation is important. Data analysis was conducted through an online non-systematic review that indicated the epidemiology, pathophysiology, and differential diagnosis and prognosis of NA. Knowledge of the clinical features of NA is not common; however, it is important in orthopedic practice because it requires differentiation from spine pathologies.

Atypical Proximal Cervical Spondylotic Amyotrophy: Case Report Demonstrating Clinical/Imaging Discrepancy

Purpose

The aim of this study was to present a novel case of unilateral proximal cervical spondylotic amyotrophy (CSA) with contralateral spinal cord compression, which is subject to misdiagnosis and missed diagnosis.

Background

CSA is the rare form of cervical spondylosis, which is characterized by severe muscle atrophy in the upper extremities. It can be classified in the proximal subtype and the distal subtype. The etiology, pathophysiology and treatment of CSA are still controversial.

Methods

A rare case of atypical proximal CSA, who presented with left shoulder and arm weakness, but cervical magnetic resonance imaging (MRI) showed large right paracentral disc herniation in the C4-5 level. Twelve weeks after undergoing anterior cervical discectomy and fusion technique in C4-5 level, the patient’s symptoms obviously recovered.

Conclusion

The opposite sides between disc herniation and clinical symptoms of upper extremity may be attributed to C5 ventral rootlet becoming stretched caused by spinal cord rotation or shift to the opposite side.

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.

A partial least squares analysis of functional status, disability, and quality of life after surgical decompression for degenerative cervical myelopathy

Previous studies aimed at identifying predictors of clinical outcomes following surgical decompression for degenerative cervical myelopathy (DCM) are limited by multicollinearity among predictors, whereby the high degree of correlation between covariates precludes detection of potentially significant findings. We apply partial least squares (PLS), a data-driven approach, to model multi-dimensional variance and dissociate patient phenotypes associated with functional, disability, and quality of life (QOL) outcomes in DCM. This was a post-hoc analysis of DCM patients enrolled in the prospective, multi-center AOSpine CSM-NA/CSM-I studies. Baseline clinical covariates evaluated as predictors included demographic (e.g., age, sex), clinical presentation (e.g., signs and symptoms), and treatment (e.g., surgical approach) characteristics. Outcomes evaluated included change in functional status (∆mJOA), disability (∆NDI), and QOL (∆SF-36) at 2 years. PLS was used to derive latent variables (LVs) relating specific clinical covariates with specific outcomes. Statistical significance was estimated using bootstrapping. Four hundred and seventy-eight patients met eligibility criteria. PLS identified 3 significant LVs. LV1 indicated an association between presentation with hand muscle atrophy, treatment by an approach other than laminectomy alone, and greater improvement in physical health-related QOL outcomes (e.g., SF-36 Physical Component Summary). LV2 suggested the presence of comorbidities (respiratory, rheumatologic, psychological) was associated with lesser improvements in functional status post-operatively (i.e., mJOA score). Finally, LV3 reflected an association between more severe myelopathy presenting with gait impairment and poorer mental health-related QOL outcomes (e.g., SF-36 Mental Component Summary). Using PLS, this analysis uncovered several novel insights pertaining to patients undergoing surgical decompression for DCM that warrant further investigation: (1) comorbid status and frailty heavily impact functional outcome; (2) presentation with hand muscle atrophy is associated with better physical QOL outcomes; and (3) more severe myelopathy with gait impairment is associated with poorer mental QOL outcomes.