Journal of neurology, neurosurgery, and psychiatry
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J. Neurol. Neurosurg. Psychiatr. · Nov 2020
Split hand and motor axonal hyperexcitability in spinal and bulbar muscular atrophy.
The 'split hand' sign refers to preferential wasting of the thenar and first dorsal interosseous muscles with relatively sparing of the hypothenar muscles in amyotrophic lateral sclerosis (ALS) and both cortical and spinal/peripheral excitotoxic mechanisms have been proposed. We aimed to study split hand and axonal excitability in spinal and bulbar muscular atrophy (SBMA) in which cortical motor neurons are intact. ⋯ Split hand is not specific to ALS and can be caused by the peripheral mechanism alone in SBMA, whereas the effect of upper motor neuron lesion cannot be excluded in ALS. Our results also suggest that SBMA and ALS share common axonal excitability changes; increased nodal persistent sodium and reduced potassium currents that may accelerate motor neuronal death and differently affect axons-innervating different muscles. Ion channel modulators could be a therapeutic option for both SBMA and ALS.
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Chronic inflammatory axonal polyneuropathy (CIAP) is defined on the basis of the clinical, electrophysiological and nerve biopsy findings and therapeutic responses of 'immunotherapy responding chronic axonal polyneuropathy (IR-CAP)'. ⋯ Diagnosis of CIAP can be made by additional documentation of 'inflammation' by high spinal fluid protein or nerve biopsy in addition to the first two diagnostic criteria of IR-CAP.