An autopsy case with adult onset type II citrullinemia showing myelopathy

Area of Science:

• Neurology
• Hepatology
• Genetics

Background:

• Hepatic myelopathy is a rare neurological complication associated with chronic liver failure, typically linked to portal-systemic shunts.
• Adult-onset type II citrullinemia (CTLN2) is an inherited metabolic disorder characterized by impaired urea cycle function and recurrent hyperammonemia.

Observation:

• A 31-year-old male with CTLN2 and a history of hepatic encephalopathy presented with progressive spastic paraparesis.
• Neurological examinations, cerebrospinal fluid analysis, and spinal MRI showed no abnormalities, and sphincter function remained intact.
• The patient experienced a fatal exacerbation of hepatic encephalopathy with severe brain edema.

Findings:

• Post-mortem spinal cord pathology revealed localized degeneration of the lateral columns, predominantly in the lower segments.
• This presentation of hepatic myelopathy is unique as the patient lacked the commonly associated portal-systemic shunt.
• The findings suggest a potential secondary induction of myelopathy due to repeated hyperammonemia episodes.

Implications:

• This case expands the understanding of hepatic myelopathy's pathophysiology, suggesting hyperammonemia as a potential direct neurotoxic factor.
• It highlights the importance of considering myelopathy in patients with urea cycle disorders presenting with unexplained neurological deficits.
• Further research is warranted to elucidate the mechanisms linking hyperammonemia to myelopathy in the absence of shunting.