E-Pearl of the Week: Figure 4 Sign

October 18, 2011

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October 18, 2011

Figure 4 Sign

Asymmetric tonic limb posturing is a useful lateralizing sign in secondarily generalized tonic–clonic seizures. It is characterized by the rigid extension of one arm at the elbow, often with the fist clenched and flexed at the wrist, while the opposite extremity is flexed at the elbow. This has been named the "Figure 4 sign" and it occurs during the tonic phase of a generalized tonic-clonic seizure. The ictal onset is contralateral to the extended arm in 92% of cases [1]. Asymmetric tonic limb posturing may be related to asymmetrical activation of the supplementary motor area or prefrontal areas [2].

References

  1. Kotagal P, Bleasel A, Geller E, Kankirawatana P, Moorjani BI, Rybicki L. Lateralizing value of asymmetric tonic limb posturing observed in secondarily generalized tonic–clonic seizures. Epilepsia 2000;41:457–462.
  2. Harvey AS, Hopkins IJ, Bowe JM, Cook DJ, Shield LK, Berkovic SF. Frontal lobe epilepsy: clinical seizure characteristics and localization with ictal 99mTc-HMPAO SPECT. Neurology 1993;43:1966–1980.

Submitted by: Seby John MD and Dimitrios A. Nacopoulos MD; Neurology Residents, Cleveland Clinic, Cleveland, Ohio

Disclosures: Drs. Seby and Nacopoulos have no disclosures.

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