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January 19 e-Pearl of the Week: Cramp Fasciculation Syndrome
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Cramp Fasciculation Syndrome
Cramp-fasciculation syndrome (CFS) is a rare, benign condition within the spectrum of peripheral nerve hyperexcitability(PNH) disorders. CFS presents with spontaneous cramps, fasciculation, stiffness and pain, [1] most commonly in the leg with no associated dysautonomia or encephalopathy. The underlying pathogenesis is the instability of distal motor axon[1]. While 24% of CFS patients had autoantibodies against voltage-gated potassium channels, [3][4] the target antigen is unknown[2] as opposed to antigens CASPR2 and less likely LGI1 that are involved in the PNH spectrum disorders like Morvan and Issac syndromes. CFS is also seen accompanying genetic or autoimmune dysfunction of ion channels, peripheral neuropathy, anterior-horn-cell disease, metabolic abnormalities or tumours (most commonly thymoma). [4] Needle EMG shows localized fasciculation potentials with normal motor unit and recruitment pattern.[5][6] Myokymic discharges are absent in CFS. Laboratory work may show elevation of creatine kinase up to twice the normal upper limit in some patients.[1] CFS is usually self-limiting with an excellent prognosis. Refractory cases require pharmacological interventions with membrane stabilizers such as carbamazepine for idiopathic cases[1] while steroids or plasmapheresis are used for autoimmune etiologies.[2]
References
- Tahmoush AJ, Alonso RJ, Tahmoush GP, Heiman-Patterson TD. Cramp,fasciculation syndrome. Neurology 1991; 41: 1021. doi: 10.1212/WNL.41.7.1021
- Lagueny, A. Cramp-fasciculation syndrome. Revue Neurologique 2005;161 (12 Pt 1): 12606.
- Hart I, Maddison P, Newsom-Davis J, Vincent A, Mills KR. Phenotypic Variants of Autoimmune Peripheral Nerve Hyperexcitability. Brain 2002; 125:1887-1895.
- Liewluck T, Klein CJ, Jones LK Jr. Cramp-fasciculation syndrome in patients with and without neural autoantibodies. Muscle Nerve 2014; 49:351-356.
- Harrison TB, Benatar M. Accuracy of repetitive nerve stimulation for diagnosis of the cramp-fasciculation syndrome. Muscle Nerve 2007; 35:776-780.
- Poyraz M, Matur Z, Aysal F, Tuzun E, Hanoglu L, Oge AE. Clinical, Electrophysiological, and Serological Evaluation of Patients with Cramp-Fasciculation Syndrome. Noro Psikiyatr Ars 2017;54:183-186. doi:10.5152/npa.2016.14816
Submitted by Schweta Rane, MBBS, University of Texas Medical Branch, Texas and Faisal Khan, MD, DABSM, DABPN, Consultant Neurologist, Sugar Land Neurology and Sleep, Texas
Dr Rane and Dr Khan report no disclosures.
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