SREAT presenting as decades of intractable seizures and isolated delusional episodes with clinical, laboratory, and EEG confirmation of treatment response

Abstract

We report a case of a 60-year-old woman with a history of intractable seizures and isolated delusional psychosis who was later diagnosed with steroid-responsive encephalopathy associated with autoimmune thyroiditis. The patient underwent right temporal lobectomy (epilepsy surgery) 15 years before coming to this clinic, but continued to have focal seizures, resulting in frequent emergency room visits thereafter. After admission for intensive inpatient video electroencephalogram monitoring and subsequent 7 months of close follow-up, both the electroencephalogram abnormalities and isolated delusional psychosis were found to be responsive to immunotherapy. This suggests that her epilepsy may be autoimmune in nature. Steroid-responsive encephalopathy associated with autoimmune thyroiditis was diagnosed after 26 years since the onset of seizures. Performing invasive epilepsy surgery in patients with autoimmune epilepsy cannot reverse the inflammatory process; therefore, it is reasonable to test for autoimmune etiologies before excision surgery on patients with medically intractable epilepsy. This case demonstrates the clinical use of quantitative electroencephalogram in assisting with the diagnosis of steroid-responsive encephalopathy associated with autoimmune thyroiditis and supports that it is a spectrum disorder with protean manifestations.

Keywords: Hashimoto’s encephalopathy; Steroid-responsive encephalopathy associated with autoimmune thyroiditis; thyroglobulin antibody; thyroperoxidase antibody.

Figure 1.

Routine EEG denotes one electrographic seizure from the right hemisphere.

Figure 2.

MRI of the brain (a): axial T2 sequence image shows encephalomalacia secondary to the right temporal lobectomy 15 years before the patient’s first visit to this clinic and (b) coronal T2 flair sequence image.

Figure 3.

EEG before the IV methylprednisolone treatment: (a) before the IV methylprednisolone treatment, the EEG displayed on the bipolar reference montage showed constant generalized rhythmic high amplitude sharp waves; (b) the EEG of (a) was displayed on the bipolar reference montage with decreased sensitivity (10 µV/mm); (c) when the EEG was displayed on the average reference montage, it showed endless generalized rhythmic high amplitude sharp waves; and (d) the EEG was displayed on the average reference montage with decreased sensitivity (10 µV/mm). During this spell (10–30 min long) (designated as blue stars in Figure 4), the EEG abnormality remained continuous.

Figure 4.

Quantitative EEG analysis: (a) before the IV methylprednisolone treatment, the continuous EEG monitoring showed spells of constant generalized rhythmic high amplitude sharp waves. These spells lasted from 10 to 30 min (denoted by the blue stars). (b) Two hours after the IV methylprednisolone treatment, the continuous EEG monitoring showed resolution of these generalized rhythmic sharp waves (the blue stars disappeared). (c) Before the IV methylprednisolone treatment, the EEG displayed on the bipolar reference montage showed constant generalized rhythmic high amplitude sharp waves. (d) After the IV methylprednisolone treatment, the EEG displayed on the bipolar reference montage showed resolution of the generalized rhythmic sharp waves.

Figure 5.

EEG after the IV methylprednisolone: (a) around 2 h after the IV methylprednisolone was administered, the EEG displayed on the bipolar reference montage showed remission of the generalized rhythmic sharp waves. Normal EEG background started to appear and mixed with the generalized rhythmic sharp waves. (b) The same EEG of (a) was displayed on the average reference montage. The breach rhythm over the right hemisphere was visible.

Figure 6.

A historical timeline of events.