Abnormal spontaneous muscle activity in plegic limb appears to initiate distal to the upper motor neuron: a case report in a stroke patient.

OBJECTIVE: To study the effect of the cutaneous silent period (CSP) on spontaneous muscle activity occurring after an upper motor injury from stroke, with a goal of developing an insight into the origin of the pathological activity. METHODS: A patient with an acute right centrum semiovale ischemic stroke had left hemiparesis. Fibrillation potentials and positive sharp waves were recorded in several left arm muscles. CSP silent period studies were performed in both arms. RESULTS: The CSP inhibited the volitional activity in the unaffected right arm. In the plegic left arm, fibrillation potentials and positive sharp waves persisted during the time period during which the CSP would have been expected, based upon the right-sided studies. CONCLUSIONS: Spontaneous activity after a cerebrovascular accident was resistant to inhibition from CSP. These findings suggest that the localization of the origin of the spontaneous activity is distal to the upper motor neuron. A confirmatory study with more patients and in a variety of stroke subtypes would strengthen this conclusion.

Effect of intravenous immunoglobulin on cerebellar ataxia and neuropathic pain associated with celiac disease.

BACKGROUND: Cerebellar syndrome and small fiber neuropathy may complicate celiac disease (CD) and may be resistant to a strict gluten-free diet. METHODS: Case series. RESULTS: We report three patients with biopsy-proven CD who developed cerebellar ataxia and neuropathic pain despite strict adherence to a gluten-free diet. A small fiber neuropathy was suggested by skin biopsy findings in two patients. All patients' symptoms, including small fiber neuropathy symptoms, responded to treatment with intravenous immunoglobulin (IVIG). Discontinuation of IVIG in two patients resulted in worsened ataxia that reversed after resumption of IVIG. CONCLUSION: Intravenous immunoglobulin may be effective in treating cerebellar ataxia and small fiber neuropathy associated with CD, suggesting an immune pathogenesis. Further prospective, controlled studies are necessary to determine the long-term response to IVIG or other immunomodulation therapy.

Posterior antebrachial cutaneous nerve conduction study technique.

PURPOSE: This paper describes an improved electrodiagnostic methodology for posterior antebrachial cutaneous nerve (PABC) neuropathy based on retrospective analysis. METHODS: Results of PABC nerve conduction studies in 14 control patients and 3 patients with left PABC neuropathy are included. Stimulation was performed 0.5 to 2.0 cm above the lateral epicondyle, and the recordings were acquired at 12 cm, 15 cm and 20 cm distally. Data was evaluated using the mean A+/- standard deviation, calculated for descriptive analysis of continuous variables whereas frequencies and percentages were determined for categorical variables. Abnormal cutoff values including side-side comparison values were established so that all normal control values would fall within the normal range. RESULTS: PABC conduction studies with 20 cm recording distance demonstrated abnormal electrodiagnostic findings in all 3 patients, while more proximal recordings failed to document the neuropathy. CONCLUSION: The recording of PABC responses at 12 cm, 15 cm and 20 cm distal to the stimulating electrode offers a more comprehensive evaluation and may be a more sensitive test for evaluation of suspected PABC neuropathy, in comparison to traditional 12 cm recording.

Anti-MAG/SGPG associated neuropathy does not commonly cause distal nerve temporal dispersion.

Patients with anti-myelin associated glycoprotein (anti-MAG) neuropathy have uniform slowing without temporal dispersion, but do usually have disproportionately distal slowing. We evaluated distal compound muscle action potential (CMAP) dispersion in 29 patients with anti-MAG/sulphated glucuronyl paragloboside (SGPG) neuropathy (titres > or = 12,800). Among 138 motor responses, 15% (tibial), 7.3% (peroneal), 10.7% (median) and 13.8% (ulnar) had distal CMAP duration > 9 ms. Disproportionate distal slowing with normal distal CMAP duration in the arms may be useful to differentiate chronic inflammatory demyelinating polyneuropathy from anti-MAG/SGPG associated neuropathy.

Characteristics of patients with sensory neuropathy diagnosed with abnormal small nerve fibres on skin biopsy.

Clinical, laboratory and electrodiagnostic (EDX) characteristics of 62 patients with sensory neuropathy with abnormal skin biopsies were reviewed. Reduced epidermal nerve fibre density (ENFD) was seen in 71% and morphological changes with normal ENFD were seen in 29% of the patients. Patients with small fibre sensory neuropathy may have associated large fibre loss undetected by routine EDX. Identified associations included abnormal glucose metabolism, Lyme vaccination, monoclonal gammopathy, vitamin B12 deficiency, coeliac disease, and diseases of the connective tissue, inflammatory bowel and thyroid. Sensory neuropathy remained undetermined in 50% of the patients.

Multifocal axonal polyneuropathy in celiac disease.

The authors report six patients with multifocal axonal polyneuropathy and the subsequent diagnosis of celiac disease (CD). Five patients did not improve or had only modest improvement following dietary intervention or immune therapies; one patient with marked weakness and mild electrodiagnostic findings had complete resolution of the neuropathy following immunomodulatory therapy. CD may be a cause of multifocal axonal polyneuropathy.

Acute quadriplegic myopathy with thick filament loss spares moving muscles: an autopsy study.

Acute Quadriplegic Myopathy with selective Thick Filament Loss (AQM-TFL) is likely an under-recognized cause of acquired areflexic quadriplegia in the ICU setting. An autopsy study of a patient with AQM-TFL revealed widespread limb thick filament loss, but with complete diaphragmatic and cardiac sparing and relative intercostal muscle sparing, was observed. Due to increased lipid accumulation, biochemical studies were performed and showed an increased free carnitine percentage, suggesting possible impaired carnitine esterification. These findings suggest that moving muscles might be resistant to the deleterious effects of AQM-TFL. These findings may have therapeutic implications.

Hepatitis C virus acute quadriparetic vasculitic neuropathy responsive to cyclophosphamide.

PURPOSE: Hepatitis C viral [HCV] infection is a chronic multisystem disorder that may have an indolent course initially. Peripheral neuropathy associated with cryoglobulinemia and a systemic vasculitis is a well-described complication of HCV infection. But this neuropathy is not known to have a late-onset acute fulminant phase. This acute fulminant phase is characterized by quadriparesis associated with pulmonary and/or renal insufficiency, and it may occur despite adequate treatment for HCV infection. The purpose of this study is to report that patients treated for chronic HCV infection may manifest a secondary progressive acute fulminant neuropathy associated with respiratory and/or renal insufficiency that is responsive to cyclophosphamide. METHODS: Case series retrospective data analysis. RESULTS: Three patients with biopsy-proven HCV associated vasculitic neuropathy manifested a secondary progressive acute fulminant course resulting in quadriparesis within 5 years of the initial diagnosis. Complete remission was achieved with cyclophosphamide therapy such that all patients became ambulatory. CONCLUSIONS: HCV-associated vasculitic neuropathy may manifest a secondary phase, which is acute, fulminant and progressive that is superimposed on an otherwise slowly progressive disorder. Cyclophosphamide therapy may abort progression and induce remission of this acute fulminant phase.

Correlation of clinical and demyelinating features in patients with neuropathy of otherwise unknown etiology.

PURPOSE: To correlate the electrodiagnostic and clinical features of patients with demyelinating abnormalities and neuropathy of otherwise unknown etiology. METHODS: We examined the records of patient with demyelinating abnormalities and no other cause for neuropathy that were evaluated in our electrophysiology laboratory over the course of a year, to correlate the clinical and electrodiagnostic features. RESULTS: Eight percent of all patients had one or more demyelinating abnormalities. Demyelinating features were significantly more numerous in generalized or asymmetric neuropathy than in distal polyneuropathy. The peroneal nerve was the most commonly affected in all phenotypes, and none of the patients with distal neuropathy had F-wave prolongation in the demyelinating range. CONCLUSIONS: The number and type of demyelinating abnormalities in patients with polyneuropathy vary with the clinical phenotype. The clinical presentation should be considered in developing or evaluating electrodiagnostic criteria for demyelinating neuropathies.

Mechanisms underlying celiac disease and its neurologic manifestations.

The extra-intestinal manifestations of celiac disease (CD), including ataxia and peripheral neuropathy, are increasingly being recognized as the presenting symptoms of this autoimmune disease. Although there is a greater understanding of the pathogenesis of the intestinal lesions in CD the mechanisms behind the neurologic manifestations of CD have not been elucidated. In this article, the authors review the cellular and molecular mechanisms behind the histopathologic changes in the intestine, discuss the presentation and characteristics of neurologic manifestations of CD, review the data on the mechanisms behind these manifestations, and discuss the diagnosis and treatment of CD. Molecular mimicry and intermolecular help may play a role in the development of neurologic complications.

Peripheral neuropathy in patients with inflammatory bowel disease.

Peripheral neuropathy (PN) in inflammatory bowel disease (IBD) patients has been reported as individual cases or small series; however, its clinical and electrodiagnostic features have not been well characterized. We conducted a retrospective review of patients with PN and either Crohn's disease (CD) or ulcerative colitis (UC). Eighteen patients with CD and 15 patients with UC were identified after other PN causes were excluded. Male predominance and mean age of PN presentation in the fifties was seen in both groups. Demyelinating neuropathy (CIDP or MMN) occurred in close to 30% of the patients, in a higher percentage of women, than in the non-demyelinating patients. One-third of CD and UC patients had small-fibre or large-fibre sensory axonal PN, while approximately 40% of the CD and UC patients had large-fibre axonal sensorimotor PN. PN symptoms began earlier in the course of CD than in UC (P < 0.05). Patients with large-fibre axonal PN were older than patients with small-fibre sensory axonal PN (P < 0.05). Close to 60% of each group received immunotherapy with different agents. Half of those treated with CD and 40% with UC had demyelinating PN. Most of the patients who completed immunotherapy in both groups improved; all the patients with demyelinating neuropathy had either moderate or major improvement. The PN syndromes in IBD patients are diverse. Demyelinating forms may occur at any time, but early in the IBD course, pure sensory neuropathy is more common. Response to immunotherapy may occur in both demyelinating and axonal neuropathies.

Celiac neuropathy.

BACKGROUND: Celiac disease (CD) is a chronic inflammatory enteropathy resulting from sensitivity to ingested gluten. Neurologic complications are estimated to occur in 10% of affected patients, with ataxia and peripheral neuropathy being the most common problems. The incidence and clinical presentation of patients with CD-associated peripheral neuropathy have not previously been investigated. OBJECTIVE: To determine the incidence of CD in patients with neuropathy and to characterize the clinical presentation. METHODS: The records of 20 patients with neuropathy and biopsy-confirmed CD were reviewed. RESULTS: Six of the 20 patients had neuropathic symptoms alone without gastrointestinal involvement, and neuropathic symptoms preceded other CD symptoms in another 3 patients. All patients had burning, tingling, and numbness in their hands and feet, with distal sensory loss, and nine had diffuse paresthesias involving the face, trunk, or lumbosacral region. Only two had weakness. Results of electrophysiologic studies were normal or mildly abnormal in 18 (90%) of the patients. Sural nerve biopsies, obtained from three patients, revealed mild to severe axonopathy. Using the agglutination assay, 13 (65%) of the patients were positive for ganglioside antibodies. Excluding patients who were referred with the diagnosis of celiac neuropathy, CD was seen in approximately 2.5% of all neuropathy patients and in 8% of patients with neuropathy and normal electrophysiologic studies seen at our center. CONCLUSION: CD is commonly associated with sensory neuropathy and should be considered even in the absence of gastrointestinal symptoms.

Current perception threshold: an adjunctive test for detection of acquired demyelinating polyneuropathies.

Current Perception Threshold (CPT) evaluation quantifies the sensory threshold to transcutaneous electrical stimulation of three sensory fiber subtypes: A-beta (2,000 Hz), A-delta (250 Hz) and C fibers (5 Hz). Demyelinating polyneuropathies tend to affect larger myelinated fibers before smaller unmyelinated fibers, and they usually begin at the proximal nerve roots or terminal axons, due to relative weakness of the blood-nerve barrier in these locations. Axonal polyneuropathies tend to affect smaller fibers before larger fibers, in a distal to proximal gradient. Ten patients with demyelinating polyneuropathy and ten patients with axonal polyneuropathy underwent CPT testing. CPT comparisons were made with regard to side-to-side asymmetries, fiber type involvement, and the ratio of fiber types involved. The C2, lateral antebrachial cutaneous, and sural distributions were examined bilaterally. Demyelinating polyneuropathies were detected with 50% sensitivity and 100% specificity. This diagnostic sensitivity is similar to that of published criteria based upon motor nerve conduction. CPT testing can distinguish demyelinating from axonal polyneuropathies. It may be particularly helpful in patients with predominantly sensory symptoms in whom EMG/NCS data may be equivocal, or in patients who decline EMG/NCS studies.

The short exercise test is normal in proximal myotonic myopathy.

OBJECTIVES: Proximal myotonic myopathy (PROMM) is a multisystem disorder that may mimic myotonic dystrophy (MD). Previously we demonstrated that the 60 s exercise test was normal in two siblings with PROMM. The test enabled distinction of PROMM from MD, as there is a well documented immediate post-exercise compound muscle action potential (CMAP) amplitude decline in MD. METHODS: We now performed exercise testing using several exercise durations in 8 PROMM patients from 6 kinships, and one MD patient, extending our previous observations. Repetitive stimulation and needle electromyography findings were also recorded. RESULTS: The 10 (n = 8), 30 (n = 5), and 60 (n = 5) s, and the 5 min (n = 1) exercise tests were normal in all PROMM patients. Specifically, the maximum post-exercise CMAP amplitude decline was 8%. In contrast, the MD patient had CMAP amplitude declines of 48% (10 s exercise test) and 26% (30 s exercise test). The distribution of repetitive stimulation and motor unit duration abnormalities were variable and less diagnostically useful. CONCLUSIONS: The 10, 30, and 60 s exercise tests help distinguish PROMM from MD. As the 10 s exercise test is rapid and easily tolerated, we recommend this test for clinical testing.

Trapezius CMAP amplitude asymmetry in accessory neuropathy.

In accessory neuropathy electrodiagnosis, upper trapezius compound muscle action potential (CMAP) latencies and amplitudes are commonly measured. The few prior reports describing middle and lower trapezius recording have traditionally emphasized latency value determination. The utility of amplitude measurement with middle and lower trapezius recording has not, to our knowledge, been previously described in individual patients with accessory neuropathy. We report three patients (A-C) who developed unilateral accessory neuropathy following surgical procedures. Accessory nerve conduction studies were performed with surface recording over the upper, middle, and lower trapezius muscles. Latency values were normal except for a prolonged lower trapezius latency value in patient B. Side-side trapezius amplitude comparisons revealed striking asymmetries from all three recording sites in patients A and B (71-95% CMAP amplitude decrements) and in the lower trapezius recording of patient C. Middle and lower trapezius side-side CMAP amplitude comparisons may increase the sensitivity of accessory neuropathy electrodiagnosis.