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Unilateral thalamic lesion mimicking genetic generalized epilepsy Volume 22, issue 6, December 2020

Figures


  • Figure 1

  • Figure 2

A 26-year-old woman presented with absence seizures since age eight, diagnosed as juvenile absence epilepsy. Absence and bilateral tonic-clonic seizures were well-controlled on valproic acid. Examination was normal. EEGshowed 3-Hz generalized spike-and-wave discharges (figure 1). MRI revealed an infiltrative lesion in the left thalamus and dorsal midbrain (figure 2). Advanced imaging suggested a low-grade glial neoplasm. Follow-up imaging showed no progression.

 

 

The thalamus plays an important role in regulating generalized epileptic networks (Avoli, 2012), including the initiation and propagation of generalized spike-and-wave discharges (Zhang et al., 2015). Prior case studies support the ability of a unilateral thalamic lesion to mimic genetic generalized epilepsy, including myoclonic, absence, and bilateral tonic-clonic seizure semiologies, and 3-Hz generalized spike/polyspike-and-wave discharges (Kelemen et al., 2006; Nguyen et al., 2006). In each case, it was not until an MRI, years later (often for medication-refractory seizures), that an underlying lesion was identified. In our patient's case, because neuroimaging was first performed at age 26, it is possible that the thalamic lesion was coincidental to her epilepsy, but we consider this less likely given the nature of the lesion and known role of the thalamus in generalized epileptic networks. This case further demonstrates that thalamic lesions can mimic the typical features of genetic generalized epilepsy, including pharmacoresponsive generalized seizure types and generalized spike-and-wave discharges in a patient with normal intellect.

Supplementary data

Summary didactic slides are available on the www.epilepticdisorders.com website.

Disclosures

None of the authors have any conflict of interest to declare.

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