RT Journal Article SR Electronic T1 Fasciculation in amyotrophic lateral sclerosis: origin and pathophysiological relevance JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 773 OP 779 DO 10.1136/jnnp-2017-315574 VO 88 IS 9 A1 de Carvalho, Mamede A1 Kiernan, Matthew C A1 Swash, Michael YR 2017 UL http://jnnp.bmj.com/content/88/9/773.abstract AB This review considers the origin and significance of fasciculations in neurological practice, with an emphasis on fasciculations in amyotrophic lateral sclerosis (ALS), and in benign fasciculation syndromes. Fasciculation represents a brief spontaneous contraction that affects a small number of muscle fibres, causing a flicker of movement under the skin. While an understanding of the role of fasciculation in ALS remains incomplete, fasciculations derive from ectopic activity generated in the motor system. A proximal origin seems likely to contribute to the generation of fasciculation in the early stages of ALS, while distal sites of origin become more prominent later in the disease, associated with distal motor axonal sprouting as part of the reinnervation response that develops secondary to loss of motor neurons. Fasciculations are distinct from the recurrent trains of axonal firing described in neuromyotonia. Fasciculation without weakness, muscle atrophy or increased tendon reflexes suggests a benign fasciculation syndrome, even when of sudden onset. Regardless of origin, fasciculations often present as the initial abnormality in ALS, an early harbinger of dysfunction and aberrant firing of motor neurons.