Index-finger pointing in generalized tonic-clonic seizures

Objective: Most patients with localization-related epilepsy (LRE) and genetic generalized epilepsy (GGE) are classified based on semiology and video-EEG, but both features occasionally fail to provide a definitive diagnosis. Several reliable lateralizing signs have been described, although hand and finger posturing has received little attention. We sought to investigate the frequency of index-finger pointing (IFP) during generalized motor convulsions as a lateralizing semiology in LRE.

Methods: We retrospectively analyzed 98 videos of generalized convulsions in 64 consecutive patients who were admitted for diagnostic video-EEG (vEEG). Demographics were recorded, and IFP ipsilateral, contralateral, and bilateral to vEEG ictal correlate was compared between LRE, GGE, and nonepileptic attacks (NEAs). The angle of IFP was measured to quantify the mean degree of IFP in "pointers" versus "nonpointers". Statistical analysis was completed using JMP 9.0.

Results: Index-finger pointing was more common in epileptic GTC seizures than in convulsive NEAs (83.6% vs 12.0%; p<0.001) and was more common in LRE compared with GGE (96% vs 56.6%; p≤0.001). The frequency of contralateral, ipsilateral, or bilateral IFP did not differ between LRE and GGE. The average angle at the MCP joint in "pointers" was 35.8° (SD 22.0°) and in "nonpointers" 3.0° (SD 7.2°).

Significance: This is the first study to examine hand and finger postures as a clinical sign to help classify epilepsy type. The presence of IFP was more common in patients with LRE than in patients with GGE and very rarely occurred in NEA. Index-finger pointing and other hand semiologies are potentially quantifiable localizing signs to aid in the characterization of patients with GTC seizures.