Hepatic Myelopathy

Hepatic myelopathy is a progressive spastic paraparesis caused by demyelination of the lateral corticospinal tracts in patients with chronic liver disease and portosystemic shunting. Sensory and sphincter functions are usually spared.

It is rare and underdiagnosed, mostly in men aged 40 to 60 years with cirrhosis and large spontaneous or surgical shunts, and can follow TIPS or a portacaval shunt. Overt encephalopathy often precedes it.

Pathophysiology.

Shunting allows gut derived neurotoxins (ammonia, manganese and others) to reach the spinal cord, damaging the corticospinal tracts at the thoracic level. Wasting of the long motor tracts causes spasticity.

Gradual onset (months) of leg stiffness, weakness and spastic gait, hyperreflexia, extensor plantar responses and clonus, without sensory loss or sphincter involvement in early disease. Arms and cranial nerves are spared.

Red flags.

• Rapid asymmetric weakness.
• Sensory level or sphincter loss (compressive lesion).
• Fever with back pain (epidural abscess).

Diagnosis is by exclusion in a cirrhotic patient with portosystemic shunting. Magnetic resonance imaging of the spine and brain is normal or shows non-specific signal change in the corticospinal tracts (and basal ganglia T1 hyperintensity). Exclude compressive myelopathy, vitamin B12 and copper deficiency, HIV and syphilis, motor neuron disease, hereditary spastic paraparesis, Wilson disease and toxic causes. Raised arterial ammonia and CT showing shunts support the diagnosis.

Differential diagnosis.

• Compressive cervical or thoracic myelopathy.
• Vitamin B12 or copper deficiency myelopathy.
• Amyotrophic lateral sclerosis.
• Hereditary spastic paraparesis.
• Multiple sclerosis.
• Lathyrism and other toxic myelopathy.

Treat the shunt and liver disease. Liver transplantation is the only reliable cure. Shunt occlusion or reduction of a TIPS can help. Control encephalopathy. Physiotherapy and spasticity treatment are given for symptoms.

• Lactulose: 20 to 30 mL orally two to three times daily, titrated to 2 to 3 soft stools daily; long term; maximum 120 mL daily; monitor sodium, potassium and hydration; reduce for diarrhoea.
• Rifaximin: 550 mg orally twice daily long term, added after a second episode of encephalopathy; maximum 1,100 mg daily; monitor diarrhoea and Clostridioides difficile infection; no renal adjustment, and use caution in severe hepatic impairment.
• Baclofen (spasticity): 5 mg orally three times daily, increased by 5 mg for each dose every 3 days; maximum 80 mg daily (40 mg daily with caution in cirrhosis); monitor sedation, confusion and encephalopathy; reduce the dose in renal impairment (creatinine clearance under 50 mL/min), and avoid abrupt withdrawal.

Monitoring. Neurological examination and gait every 3 months; ammonia and encephalopathy grading with each admission.

Referral and escalation. Hepatology, neurology and the transplant centre early, because the damage is often irreversible.