Long Exercise Test in Periodic Paralysis: A Bayesian Analysis.

Introduction: The long exercise test (LET) is used to assess the diagnosis of periodic paralysis (PP), but LET methodology and normal "cutoff" values vary.

Methods: To determine optimal LET methodology and cutoffs, we reviewed LET data (abductor digiti minimi motor response amplitude, area) from 55 patients with PP (32 genetically definite) and 125 controls. Receiver operating characteristic curves were constructed, and area under the curve (AUC) was calculated to compare (1) peak-to-nadir versus baseline-to-nadir methodologies and (2) amplitude versus area decrements.

Autonomic dysfunction is a major feature of cerebellar ataxia, neuropathy, vestibular areflexia 'CANVAS' syndrome.

Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) is a recently recognized neurodegenerative ganglionopathy. Prompted by the presence of symptomatic postural hypotension in two patients with CANVAS, we hypothesized that autonomic dysfunction may be an associated feature of the syndrome. We assessed symptoms of autonomic dysfunction and performed autonomic nervous system testing among 26 patients from New Zealand.

Treatment of neuromuscular channelopathies: current concepts and future prospects.

Our understanding of the molecular pathogenesis of the neuromuscular ion channelopathies has increased rapidly over the past two decades due to the identification of many of the genes whose mutation causes these diseases. These molecular discoveries have facilitated identification and classification of the hereditary periodic paralyses and the myotonias, and are likely to shed light on acquired ion channelopathies as well. Despite our better understanding of the pathogenesis of these disorders, current treatments are largely empirical and the evidence in favor of specific therapy largely anecdotal.

Clinical evaluation of membrane excitability in muscle channel disorders: potential applications in clinical trials.

Muscle channelopathies are inherited disorders that cause paralysis and myotonia. Molecular technology has contributed immeasurably to diagnostic testing, to correlation of genotype with phenotype, and to insight into the pathophysiology of these disorders. In most cases, the diagnosis of muscle channelopathy is still made on clinical grounds, but is supported by ancillary laboratory and electrodiagnostic testing such as serum potassium measurement, exercise testing, repetitive nerve stimulation, needle electromyography, calculation of muscle fiber conduction velocity, or electromyography power spectra.

Dispersion of the distal compound muscle action potential in chronic inflammatory demyelinating polyneuropathy and carpal tunnel syndrome.

Median neuropathy at the wrist can confound the electrodiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP), since both conditions can prolong median distal motor latency. Dispersion of the distal CMAP (DCMAP) has recently emerged as a potentially useful adjunct in the electrodiagnosis of CIDP, with good specificity in distinguishing CIDP from certain axon-loss disorders. However, it is uncertain whether focal compression neuropathies produce dispersion of the DCMAP in a manner similar to CIDP.