Lateralizing Value of Lower Extremity Asymmetric Tonic Posturing in Mesial Frontoparietal Epilepsy - Old Terminology into New Terminology as the “ballerina Sign”
Abstract number :
2.518
Submission category :
3. Neurophysiology / 3A. Video EEG Epilepsy-Monitoring
Year :
2024
Submission ID :
1416
Source :
www.aesnet.org
Presentation date :
12/8/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Stephen Orr, MD – University of Pittsburgh Medical Center
Thandar Aung, MD, MS – University of Pittsburgh
Rationale: Originally described by Ajmone-Marsan and Ralston in 1957, asymmetric tonic limb posturing (ATLP) of the upper extremities—otherwise known as the “figure 4 sign”—was later found to have lateralizing significance in seizure. In most cases where the sign is present, the arm contralateral to the seizure focus extends while the arm ipsilateral to the focus flexes, making the shape of the number 4. While this sign has been well-characterized, there is no data that systematically analyzed the equivalent sign in the lower extremities to determine if it has lateralizing significance. We have called the lower extremity ATLP the “ballerina sign” given its appearance resembling a ballerina performing a pirouette in which one leg is flexed at the hip and knee while the other is simultaneously extended. We hypothesized that the ballerina sign in the presence or absence of the figure 4 sign, with or without secondary generalization, would provide lateralizing value with leg extension contralateral and leg flexion ipsilateral to the seizure focus.
Methods: To address this hypothesis, we analyzed video-recorded seizures from patients at the University of Pittsburgh Epilepsy Monitoring Unit with mesial frontoparietal epilepsy (anecdotally known to display this sign). Under the IRB of U of Pitt, we retrospectively analyzed 6 patients with confirmed mesial frontoparietal epilepsy. Of these, we studied all seizures of the phase I scalp and intracranial EEG recording to characterize semiology and lateralizing significance of the ballerina sign. We analyzed 185 seizures from 6 patients who displayed the sign (See Table 1).
Results: Out of 185 seizures, 73 displayed the ballerina sign. The sign co-presented with the figure 4 sign in 15 percent (11/73) of seizures. 8.2 percent (6/73) of these seizures progressed to secondary generalization. The extended leg was contralateral to side of ictal onset in 93 percent (68/73). The lateralizing value of the sign was higher in focal seizures in which all (67/67) showed an extended leg contralateral to side of ictal onset. If there was associated figure 4, the mean time from ballerina sign to figure 4 was 0.1 seconds (n = 11; SD = 2.95). The mean time from ballerina sign to secondary generalization was 17.2 seconds (n = 6; SD = 10.7). When the sign occurred in absence of the figure 4 sign, 94 percent (59/63) presented with the extended leg contralateral to the side of ictal onset.
Conclusions: Our preliminary data suggest that the ballerina sign has lateralizing value primarily in focal seizures, even when the figure 4 sign is absent. Recognition of this sign can aid in pre-surgical planning.
Funding: This research received no external funding.
Neurophysiology