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1.  Electrophysiological study in neuromuscular junction disorders 
This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS), congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG) helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS). SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation.
doi:10.4103/0972-2327.107690
PMCID: PMC3644779  PMID: 23661960
Acetylcholine; congenital myasthenic syndromes; Lambert–Eaton myasthenic syndrome; myasthenia gravis; repetitive nerve stimulation; single-fiber electromyography
2.  Hyperreflexic Guillain-Barré syndrome 
Guillain-Barré syndrome (GBS) is an acquired acute autoimmune polyradiculoneuropathy. The 2 features considered essential for the diagnosis of GBS are progressive motor weakness and areflexia. There have been several descriptions of reflex preservation and hyperreflexia in axonal variant of GBS in Chinese, Japanese, and European populations but it is not common in the Indian subcontinent. We report 2 such cases discussing the pathophysiology and management aspects. This case report is to impress upon treating physicians and neurologists in training that a hyperreflexic variant of GBS albeit rare, should not be missed in a given clinical setting.
doi:10.4103/0972-2327.74195
PMCID: PMC3021938  PMID: 21264143
AMAN; autoimmune polyradiculoneuropathy; Guillain-Barré syndrome
3.  An elusive diagnosis: Scedosporium apiospermum infection after near-drowning 
A 51-year-old male was admitted in our institute following an episode of near-drowning. He later developed ventriculitis and cerebral ring-enhancing lesions. He died following a subarachnoid hemorrhage due to rupture of a mycotic aneurysm involving the right fetal posterior cerebral artery. Scedosporium apiospermum was isolated from the cerebrospinal fluid. Central nervous system invasion by S apiospermum may present insidiously in near-drowning patients and, therefore, requires a high index of suspicion. In cases with the characteristic cerebral ring-enhancing lesions and concomitant ventriculitis, treatment should be instituted while awaiting fungal culture. With this article we intend to alert neurologists, intensivists, and physicians to this near fatal infection, as early identification and prompt treatment with voriconazole may be life saving.
doi:10.4103/0972-2327.70878
PMCID: PMC2981763  PMID: 21085536
Fungal meningitis; near-drowning; Pseudallescheria boydii; Scedosporium apiospermum
4.  Muscle channelopathies and electrophysiological approach 
Myotonic syndromes and periodic paralyses are rare disorders of skeletal muscle characterized mainly by muscle stiffness or episodic attacks of weakness. Familial forms are caused by mutation in genes coding for skeletal muscle voltage ionic channels. Familial periodic paralysis and nondystrophic myotonias are disorders of skeletal muscle excitability caused by mutations in genes coding for voltage-gated ion channels. These diseases are characterized by episodic failure of motor activity due to muscle weakness (paralysis) or stiffness (myotonia). Clinical studies have identified two forms of periodic paralyses: hypokalemic periodic paralysis (hypoKPP) and hyperkalemic periodic paralysis (hyperKPP), based on changes in serum potassium levels during the attacks, and three distinct forms of myotonias: paramyotonia congenita (PC), potassium-aggravated myotonia (PAM), and myotonia congenita (MC). PC and PAM have been linked to missense mutations in the SCN4A gene, which encodes α subunit of the voltage-gated sodium channel, whereas MC is caused by mutations in the chloride channel gene (CLCN1). Exercise is known to trigger, aggravate, or relieve symptoms. Therefore, exercise can be used as a functional test in electromyography to improve the diagnosis of these muscle disorders. Abnormal changes in the compound muscle action potential can be disclosed using different exercise tests. Five electromyographic (EMG) patterns (I-V) that may be used in clinical practice as guides for molecular diagnosis are discussed.
doi:10.4103/0972-2327.40221
PMCID: PMC2781140  PMID: 19966974
Channelopathy; electromyographic; ion channel; myotonia; periodic paralysis

Results 1-4 (4)