Vinciane Van Parijs

Critical illness myopathy unrelated to corticosteroids or neuromuscular blocking agents

Acute myopathy occurs in critically ill patients, receiving neuromuscular blocking agents or corticosteroids during intensive care hospitalisation. We report three patients with acute quadriplegic myopathy, two of whom were not exposed to corticosteroids or neuromuscular blocking agents. The first of these latter two patients had a history of generalised anoxia with coma related to surgery, complicated by multiple organ failure and sepsis. The second patient, suffering from acute leukaemia, developed sepsis and acute respiratory distress syndrome with the need for mechanical ventilation in the intensive care unit. Electrophysiological studies and muscle biopsy findings were consistent with the diagnosis of critical illness myopathy with loss of myosin filaments. Selective loss of myosin was confirmed by biochemical analysis of muscle. These findings demonstrate that acute myopathy with loss of myosin filaments may occur in patients with severe systemic illness without exposure to corticosteroids or neuromuscular blocking agents.

Effects of low frequency filtering on distal compound muscle action potential duration for diagnosis of CIDP: A Japanese–European multicenter prospective study

OBJECTIVE The duration of the distal compound muscle action potential (DCMAP) is a useful index to detect demyelination in the distal nerve segments. However in published electrodiagnostic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP), the cut-off values of DCMAP duration are defined using an EMG low frequency filter of only 20 Hz. We aimed to provide widely-available reference data using several low cut filters. METHODS In 13 Japanese and European tertiary centers, DCMAP duration data using 2, 5, 10, and 20 Hz low frequency filters were prospectively collected from 147 normal controls, 59 patients with typical CIDP, and 100 with diabetic polyneuropathy. Optimal cut-off values were calculated with receiver-operating characteristic curves, offering 100% specificity versus normal controls. RESULTS The higher low frequency filter was associated with significantly shorter DCMAP duration in all groups. For CIDP diagnosis, the calculated cut-off values had a sensitivity ranging from 51% to 66%, and a specificity versus diabetic neuropathy from 96% to 98%. CONCLUSIONS Our results show that DCMAP duration is largely dependent on low frequency filter settings, but is a useful index for CIDP diagnosis when the cut-off values are properly determined at each filter setting. SIGNIFICANCE Our data provide the systematic reference values of DCMAP duration for CIDP diagnosis available for most EMG laboratories.

Neuromyotonia and myasthenia gravis without thymoma

Neuromyotonia is a syndrome characterised by motor unit hyperactivity leading to muscle cramps, fasciculations, muscle stiffness, and persistent muscle contraction. In most neuromyotonia patients, the disorder is acquired. An autoimmune or paraneoplastic origin is common.1–3 Myasthenia gravis, thyrotoxicosis, systemic sclerosis, inflammatory demyelinating neuropathies, thymoma, bronchial carcinoma, and small cell lung cancer may be associated. Here, we report a patient with neuromyotonia, associated with myasthenia gravis and anti-voltage-gated potassium channels (VGKC) and anti-acetylcholine receptor (AChR) antibodies without thymoma. A 58 year old man of Portuguese descent presented at our neuromuscular clinic with dysesthesia and hypesthesia in the first three fingers of the right hand. Symptoms had started nine years before and had been attributed to cervical radiculopathy. Over the years, the symptoms had been fluctuating but for the past two months they had become debilitating. Therefore, the patient sought a second opinion. The patient volunteered that, although right hand pain was his main complaint, for many …

A homozygous DPM3 mutation in a patient with alpha-dystroglycan-related limb girdle muscular dystrophy.

Defects of O-linked glycosylation of alpha-dystroglycan cause a wide spectrum of muscular dystrophies ranging from severe congenital muscular dystrophy associated with abnormal brain and eye development to mild limb girdle muscular dystrophy. We report a female patient who developed isolated pelvic girdle muscle weakness and wasting, which became symptomatic at age 42. Exome sequencing uncovered a homozygous c.131T > G (p.Leu44Pro) substitution in DPM3, encoding dolichol-P-mannose (DPM) synthase subunit 3, leading to a 50% reduction of enzymatic activity. Decreased availability of DPM as an essential donor substrate for protein O-mannosyltransferase (POMT) 1 and 2 explains defective skeletal muscle alpha-dystroglycan O-glycosylation. Our findings show that DPM3 mutations may lead to an isolated and mild limb girdle muscular dystrophy phenotype without cardiomyopathy.

Guillain-BarrÉ syndrome subtype diagnosis: A prospective multicentric European study: GBS Subtype Diagnosis

Introduction: There is uncertainty as to whether the Guillain‐Barré syndrome (GBS) subtypes, acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and acute motor axonal neuropathy (AMAN), can be diagnosed electrophysiologically. Methods: We prospectively included 58 GBS patients. Electrodiagnostic testing (EDX) was performed at means of 5 and 33 days after disease onset. Two traditional and one recent criteria sets were used to classify studies as demyelinating or axonal. Results were correlated with anti‐ganglioside antibodies and reversible conduction failure (RCF). Results: No classification shifts were observed, but more patients were classified as axonal with recent criteria. RCF and anti‐ganglioside antibodies were present in both subtypes, more frequently in the axonal subtype. Discussion: Serial EDX has no effect on GBS subtype proportions. The absence of exclusive correlation with RCF and anti‐ganglioside antibodies may challenge the concept of demyelinating and axonal GBS subtypes based upon electrophysiological criteria. Frequent RCF indicates that nodal/paranodal alterations may represent the main pathophysiology. Muscle Nerve 58: 23–28, 2018.