# Hashimoto's Encephalopathy as a Cause of Persistent Myoclonic Jerks: A Report of a Unique Case

## TL;DR

A rare case shows that Hashimoto's encephalopathy can cause persistent myoclonic jerks and neurological symptoms, often misdiagnosed as epilepsy.

## Contribution

Highlights Hashimoto's encephalopathy as a potential cause of myoclonic jerks in adults with normal imaging and EEG results.

## Key findings

- A 45-year-old woman with myoclonic jerks and elevated thyroid antibodies showed significant improvement with corticosteroids.
- Hashimoto's encephalopathy should be considered in differential diagnosis when common neurological tests are normal.
- Corticosteroid response is a key diagnostic criterion for Hashimoto's encephalopathy.

## Abstract

Identifying the cause of frequent episodes of myoclonic jerks accompanied by non-specific symptoms in a previously healthy adult can be challenging, especially after ruling out common pathologies such as epilepsy. This case emphasises the importance of considering autoimmune etiologies, particularly Hashimoto's encephalopathy (HE), in the differential diagnosis of encephalopathy.

We present a case of a 45-year-old female patient with a 10-month history of generalised myoclonic jerks, headaches, and word-finding difficulties, all occurring without any alteration in consciousness. Her physical and neurological examinations, brain MRI, 72-hour EEG, and EMG results were unremarkable. However, thyroid peroxidase and anti-thyroglobulin antibody titers were markedly elevated, despite an euthyroid profile. The patient was initiated on oral corticosteroids, resulting in significant clinical improvement.

HE, also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis, is a rare neurological disorder that is linked to Hashimoto's thyroiditis. It typically follows an acute or subacute course and often responds dramatically to corticosteroid therapy, a response that is considered a key diagnostic criterion.