# Late-Onset Leigh Syndrome With Protracted Gastrointestinal Manifestations: A Rare Case Report

## TL;DR

A 42-year-old woman with late-onset Leigh syndrome showed unusual gastrointestinal symptoms and responded well to thiamine treatment.

## Contribution

This case report highlights a rare instance of adult-onset Leigh syndrome with gastrointestinal symptoms and successful thiamine treatment.

## Key findings

- The patient showed hyperintensities in the basal ganglia and brain stem on MRI.
- Elevated lactate levels in serum and cerebrospinal fluid were observed.
- Muscle biopsy revealed reduced cytochrome oxidase activity, supporting the LS diagnosis.

## Abstract

Although Leigh syndrome (LS) is a neurodegenerative disorder of infancy, adult-onset LS has also been rarely reported. We report a case of late-onset LS in a 42-year-old female who presented with protracted gastrointestinal manifestations, chronic headaches, ataxia, and loss of consciousness. Brain magnetic resonance imaging (MRI) revealed hyperintensities in the bilateral basal ganglia and brain stem. Serum and cerebrospinal fluid lactate levels were significantly raised. Muscle biopsy showed reduced cytochrome oxidase (COX) activity. She was diagnosed with probable diagnosis of late-onset LS based on her clinical features, radiological findings, biochemical results, and biopsy findings. She responded well to intravenous thiamine, and her symptoms gradually improved.