3.244 Polyphasic MEPs in myoclonus dystonia: A TMS study

Salm, S. van der; Rootselaar, A.F. van; Foncke, E.M.J.; Koelman, Johannes H. T. M.; Bour, L.J.; Bhatia, Kailash P.; Rothwell, John C.; Tijssen, Marina A. J.

doi:10.1016/s1353-8020(08)70882-4

Cited by 2 publications

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“…Previous research also concluded that the polyphasic activity identified by TMS in patients with myoclonus dystonia may be related to mutations in the SGCE gene encoding a transmembrane protein, thereby increasing synaptic instability within the corticospinal tract. 7 , 8 While SCGE is not recognized as a genetic contributor to IGE, further corroboration of these results might motivate the hypothesis that this gene could provide a potential putative central mechanism. However, further investigation is certainly required before its pathophysiologic mechanism can be better understood.…”

Section: Discussionmentioning

confidence: 83%

“…In amyotrophic lateral sclerosis (ALS), they may reflect central corticospinal abnormality, 5 and in myoclonus dystonia, they may reflect abnormal variability in the patterning of descending corticospinal volleys evoked by TMS (so-called I waves) 6 and hence alteration in the pattern and timing of recruitment of spinal motor neurons. 7 , 8 Polyphasic responses have also been observed in healthy children 9 becoming less polyphasic with age.…”

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confidence: 96%

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Motor evoked potential polyphasia

et al. 2015

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Objective:We compared the motor evoked potential (MEP) phases using transcranial magnetic stimulation in patients with idiopathic generalized epilepsy (IGE), their relatives, and healthy controls, hypothesizing that patients and their unaffected relatives may share a subtle pathophysiologic abnormality.Methods:In a cross-sectional study, we investigated 23 patients with IGE, 34 first-degree relatives, and 30 matched healthy controls. Transcranial magnetic stimulation was performed to produce a series of suprathreshold single-pulse MEPs. A semiautomated method was used to count phases. We compared between groups the mean number of MEP phases, the stimulus-to-stimulus variability in MEP phases, and the proportion of polyphasic MEPs within subjects.Results:Patients with IGE and their relatives had a significantly increased number of MEP phases (median for patients 2.24, relatives 2.17, controls 2.01) and a significantly higher proportion of MEPs with more than 2 phases than controls (median for patients 0.118, relatives 0.088, controls 0.013). Patients had a greater stimulus-to-stimulus variability in number of MEP phases than controls. There were no differences between patients and relatives.Conclusion:Increased MEP polyphasia in patients with IGE and their first-degree relatives may reflect transient abnormal evoked oscillations. The presence of polyphasic MEPs in relatives as well as patients suggests that MEP polyphasia is not related to treatment, and is in isolation insufficient to predispose to epilepsy. Polyphasic MEP may be a novel endophenotype in IGE.

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Section: Discussionmentioning

confidence: 83%

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confidence: 96%

Motor evoked potential polyphasia

et al. 2015

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“…7,8 While SCGE is not recognized as a genetic contributor to IGE, further corroboration of these results might motivate the hypothesis that this gene could provide a potential putative central mechanism. However, further investigation is certainly required before its pathophysiologic mechanism can be better understood.…”

Section: Discussionmentioning

confidence: 84%

“…To our knowledge, this is the first report of polyphasic MEPs in epilepsy, although they have previously been documented in ALS 5 and myoclonus dystonia. 7,8 In these studies, the polyphasia was attributed to central mechanisms. We speculate that this is due to abnormal timing and patterning of the descending volleys in the corticospinal tract, termed I waves.…”

Section: Discussionmentioning

confidence: 99%

“…In amyotrophic lateral sclerosis (ALS), they may reflect central corticospinal abnormality, 5 and in myoclonus dystonia, they may reflect abnormal variability in the patterning of descending corticospinal volleys evoked by TMS (so-called I waves) 6 and hence alteration in the pattern and timing of recruitment of spinal motor neurons. 7,8 Polyphasic responses have also been observed in healthy children 9 becoming less polyphasic with age. Asymptomatic relatives of patients with IGE may share an endophenotype that alone is not sufficient to cause seizures.…”

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confidence: 97%

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Motor evoked potential polyphasia: A novel endophenotype of idiopathic generalized epilepsy

Valls‐Solé¹,

Pawley²,

Ziemann³

et al. 2015

Neurology

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Objective: We compared the motor evoked potential (MEP) phases using transcranial magnetic stimulation in patients with idiopathic generalized epilepsy (IGE), their relatives, and healthy controls, hypothesizing that patients and their unaffected relatives may share a subtle pathophysiologic abnormality.Methods: In a cross-sectional study, we investigated 23 patients with IGE, 34 first-degree relatives, and 30 matched healthy controls. Transcranial magnetic stimulation was performed to produce a series of suprathreshold single-pulse MEPs. A semiautomated method was used to count phases. We compared between groups the mean number of MEP phases, the stimulus-to-stimulus variability in MEP phases, and the proportion of polyphasic MEPs within subjects.Results: Patients with IGE and their relatives had a significantly increased number of MEP phases (median for patients 2.24, relatives 2.17, controls 2.01) and a significantly higher proportion of MEPs with more than 2 phases than controls (median for patients 0.118, relatives 0.088, controls 0.013). Patients had a greater stimulus-to-stimulus variability in number of MEP phases than controls. There were no differences between patients and relatives.Conclusion: Increased MEP polyphasia in patients with IGE and their first-degree relatives may reflect transient abnormal evoked oscillations. The presence of polyphasic MEPs in relatives as well as patients suggests that MEP polyphasia is not related to treatment, and is in isolation insufficient to predispose to epilepsy. Polyphasic MEP may be a novel endophenotype in IGE.

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3.244 Polyphasic MEPs in myoclonus dystonia: A TMS study

Cited by 2 publications

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Motor evoked potential polyphasia

Motor evoked potential polyphasia

Motor evoked potential polyphasia: A novel endophenotype of idiopathic generalized epilepsy

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