Distal-type Cervical Spondylotic Amyotrophy Research Articles

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

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. 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. 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 < 6months group. Cervical alignments and preoperative MMT grade were not statistically associated with poor outcomes. Patients with poor outcomes had symptoms for a longer duration. We found tolerable clinical outcomes within 6months 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.

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

Changes in Central Motor Conduction Time and Its Implication on Dysfunction of Distal Upper Limb in Distal-Type Cervical Spondylotic Amyotrophy.

Distal-type cervical spondylotic amyotrophy (CSA) is an uncommon syndrome associated with cervical spondylosis. The pathogenic mechanism of distal-type CSA is still unclear. The aim of the current study was to analyze central motor conduction time (CMCT) in the cases with distal-type CSA and to investigate the role of cervical cord compressive injury in the distal-type CSA. Both 28 cases with distal-type CSA and 21 healthy subjects accepted CMCT measures, motor unit number estimation, handgrip strength examination, and magnetic resonance imaging evaluation. In this study, nine (9/28, 32.1%) cases with CSA presented with prolonged CMCT, and both reduced number of motor units and decreased handgrip strength were found in these 9 cases (P < 0.05). Magnetic resonance imaging evaluation showed that 7 of these 9 patients presented with proximal cervical cord compression with or even without distal selective compression consistent with segmental atrophy. A negative relationship between CMCT and both number of motor units and handgrip strength was found on the symptomatic side (P < 0.05), and there was a positive correlation between CMCT and amplitude of single motor unit potentials on the less symptomatic side (P < 0.05). Corticospinal tract damage caused by proximal spinal cord compression may induce distal motor unit loss to worsen in some cases with distal-type CSA, which may contribute to the dysfunction of the distal upper limb in some cases with distal-type CSA. Therefore, treatment and rehabilitation efforts should account for both distal selective compression and proximal cord compression in distal-type CSA.

T25. Changes in central motor conduction time and its implication in the pathogenesis of distal-type cervical spondylotic amyotrophy

The true pathogenesis of cervical spondylotic amyotrophy (CSA) remains controversial. One of the current hypotheses for the etiology of CSA mainly involves selective compression of the ventral nerve roots and/or anterior horn cells by a bony spur or herniated disc. Some scholars have proposed that CSA may be ascribed to ischemia of anterior horn cells caused by compressive injury of anterior spinal artery. Recently published studies demonstrated that chronic incomplete cervical cord compression can cause the loss of motor neurons in the spinal anterior horn caudal to the level of the compressive injury, which was described as trans-synaptic damage. Although CSA was previously considered a neurological disease involving only lower motor neurons (LMNs), some authors revealed that approximately 28.6–66.7% of distal-type CSA patients had significant lower limb hyperreflexia, which is consistent with upper motor neuron (UMN) lesions. Therefore, trans-synaptic damage may be involved in the pathogenesis of distal-type CSA. The present study has been undertaken to evaluate central motor conduction in distal-type CSA patients and to analyze the role of trans-synaptic damage in the pathogenesis of distal-type CSA. Central motor conduction time (CMCT) to both upper and lower limbs was measured in 28 distal-type CSA patients and 21 controls, and all subjects underwent further motor unit number estimation (MUNE), handgrip strength examination (HGS) and magnetic resonance imaging evaluation. Prolonged CMCT was recorded in 9/28 (32.1%) CSA patients, and both lower MUNE values and smaller HGS were observed in these 9 cases (P < 0.05). Imaging analysis demonstrated that 5 of these 9 cases had cervical compression both proximally and distally, and severe proximal cervical compression without distal selective compression was found in the other two cases (2/9, 22.2%). There was an inverse correlation between CMCT and both MUNE values and HGS on symptomatic side (P < 0.05), and a positive relationship between CMCT and amplitude of single motor unit potentials was found on less-symptomatic side (P < 0.05). Distal-type CSA patients may have substantial corticospinal tract lesions, and trans-synaptic damage caused by these lesions may be involved in the pathogenesis of distal-type CSA. Therefore, clinicians should be cautious when evaluating and managing distal-type CSA patients, especially the cases with additional proximal cervical compression, because severe muscular atrophy may be caused by both trans-synaptic damage and selective compression.

Altered motor axonal excitability in patients with cervical spondylotic amyotrophy

ObjectiveTo investigate the changes in motor axonal excitability properties in cervical spondylotic amyotrophy (CSA). MethodsThreshold tracking was used to measure the median motor axons in 21 patients with CSA, 10 patients with cervical spondylotic radiculopathy (CSR) and 16 normal controls. ResultsCompared with normal controls, patients with distal-type CSA showed increased threshold electrotonus hyperpolarization (TEh [90–100]) and increased superexcitability on the symptomatic side (P < 0.05), which are suggestive of distal motor axonal hyperpolarization, presumably due to motor axonal regeneration. More importantly, compared with normal controls and CSR cases, both distal- and proximal-type CSA cases showed lower accommodation during depolarising currents (reduced S2 accommodation, decreased TEd [undershoot] and/or lower subexcitability) (P < 0.05), indicating that slow K+ conductance may be less active in motor axons in patients with CSA. ConclusionsThe present study demonstrated changes in motor axonal excitability in patients with CSA compared with both normal controls and patients with CSR. SignificanceLess expression of slow K+ conductance may confer greater instability in membrane potential in CSA, thereby presumably contributing to the increased vulnerability of motor axons in patients with CSA.

A Novel Scoring System Associated With Surgical Outcome of Distal-type Cervical Spondylotic Amyotrophy.

A single-center retrospective study. To elucidate the pathology of distal-type cervical spondylotic amyotrophy (CSA) and to assess predictive factors and a novel scoring system associated with surgical outcome. Because of its rarity, the pathophysiology and surgical outcome of distal-type CSA are less well understood compared with proximal-type CSA. Surgical procedures were performed in 13 patients with distal-type CSA. Patients were classified into 2 groups: those with good recovery of muscle power (group 1, n=4) and those with fair recovery (group 2, n=9). All patients underwent magnetic resonance imaging. Central motor conduction time was recorded in abductor digit minim and compound muscle action potentials (CMAPs) were recorded in extensor carpi dig. Predictive factors associated with surgical outcome and a scoring system based on clinical, radiologic, and electrophysiological findings were evaluated. Twelve of 13 patients were scored for the following features: (1) duration of symptoms ≥13 months, (2) initial manual muscle testing ≤1, (3) multiple compressions in magnetic resonance imaging, (4) CMAPs amplitudes on affected side <1 mV, (5) CMAPs amplitudes on normal side <7.2 mV, (6) central motor conduction time longer than 7.4 ms, (7) the ratio of CMAPs amplitudes comparison with the normal side <50%. At final follow-up, 2 patients were graded excellent, 2 good, 9 fair, and 0 poor. None of the predictive factors was significantly different between groups 1 and 2. The mean score in group 2 (5.12±1.12) was significantly higher than for group 1 (2±1.15; P=0.006). Although all 8 patients in group 2 scored ≥4 points, all 4 patients in group 1 scored ≤3. Comprehensive assessment using a scoring system is useful for predicting the surgical outcome of distal-type CSA. Surgeons should be aware that a score of ≥4 points correlates with poor surgical outcome on motor function.

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.

Evaluation of characteristics and surgical outcomes in cervical spondylotic amyotrophy.

Background:Cervical spondylotic amyotrophy (CSA) is a rare clinical syndrome resulting from cervical spondylosis. Surgical treatment includes anterior cervical decompression and fusion (ACDF), and laminoplasty with or without foraminotomy. Some studies indicate that ACDF is an effective method for treating CSA because anterior decompression with or without medial foraminotomy can completely eliminate anterior and/or anterolateral lesions. We retrospectively evaluated outcome of surgical outcome by anterior cervical decompression and fusion (ACDF).Materials and Methods:28 CSA patients, among whom 12 had proximal type CSA and 16 had distal type CSA, treated by ACDF, were evaluated clinicoradiologically. The improvement in atrophic muscle power was assessed by manual muscle testing (MMT) and the recovery rate of the patients was determined on the basis of the Japanese Orthopedic Association (JOA) scores. Patient satisfaction was also examined.Results:The percentage of patients, who gained 1 or more grades of muscle power improvement, as determined by MMT, was 91.7% for those with proximal type CSA and 37.5% for those with distal type CSA (P < 0.01). The JOA score-based recovery rates of patients with proximal type and distal type CSA were 60.8% and 41.8%, respectively (P < 0.05). Patient satisfaction was 8.2 for those with proximal type CSA and 6.9 for those with distal type CSA (P < 0.01). A correlation was observed among the levels of improvement in muscle power, JOA score based recovery rate, patient satisfaction and course of disease (P < 0.05).Conclusion:ACDF can effectively improve the clinical function of patients with CSA and result in good patient satisfaction despite the surgical outcomes for distal type CSA being inferior to those for proximal type CSA. Course of disease is the fundamental factor that affects the surgical outcomes for CSA. We recommend that patients with CSA undergo surgical intervention as early as possible.

Distal type cervical spondylotic amyotrophy

Distal type cervical spondylotic amyotrophy

Surgical outcome for distal type cervical spondylotic amyotrophy by electrophysiologic assessment

Surgical outcome for distal type cervical spondylotic amyotrophy by electrophysiologic assessment

Surgical results of distal-type cervical spondylotic amyotrophy

Surgical results of distal-type cervical spondylotic amyotrophy

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

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. 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. 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. 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.

Pathology of proximal and distal type cervical spondylotic amyotrophy

Pathology of proximal and distal type cervical spondylotic amyotrophy