S159. Long latency reflexes in myoclonic epilepsies

Abstract

Long latency reflexes (LLRs) are medium to late latency responses which are obtained over a muscle after a peripheral stimulation. In epilepsy, presence and amplitudes are supposed to be higher due to increased cortical excitability. We aimed to analyze LLRs in juvenile myoclonic epilepsy (JME) and progressive myoclonic epilepsy (PME), to determine the frequency of three subtypes and to analyze whether parameters regarding LLRs may be used in differentiating these two disorders. Our hypothesis was cortical excitability and amplitudes and frequency of LLRs would be higher in PME. We included 30 patients with JME, 18 patients with PME and 28 healthy subjects. LLRs were recorded over abductor policis brevis muscle after stimulating median nerve at wrist during rest and active movement. Latencies and amplitudes of segmental reflex and LLRs, presence of LLR I, II, and III, the ratio of segmental reflex amplitude and LLR amplitude were compared among three groups. ROC curves were formed for LLR I amplitude and amplitude ratio to evaluate ‘cut-off’ values in differentiating PME and JME. C reflex was detected in only PME group and LLR I presence during active movement was the highest in PME group (57.9%, p = 0,001). Although LLR I amplitude was also the highest in PME group, ratio was higher in JME group since amplitude of segmental reflex was also higher in patients with PME. Both parameters were higher in PME and JME groups compared to healthy subjects (LLR I amplitude: p = 0.005 and ratio: p = 0.011, Kruskal–Wallis test). LLR I amplitude was able to differentiate patients with epilepsy and healthy subjects with an accuracy of 57–82% (p = 0.008) whereas ratio was able to recognize patients with an accuracy of 60–86% (p = 0.003). Ratio above 1.05 had the sensitivity and specificity of 77.8% and 71%, respectively in diagnosing patients with PME or JME. Presence of C reflex and higher LLR I amplitudes suggest the presence of exaggerated cortical response to peripheral stimuli in PME. However, cortical excitability measured by LLR I amplitude is high in both JME and PME and hence does not provide differentiation of these two disorders.