Post-Traumatic Epilepsy

Post-traumatic epilepsy is recurrent unprovoked seizures that follow traumatic brain injury. Early seizures (within 7 days) are acute symptomatic, and late seizures (after 7 days) indicate epilepsy. The risk after severe injury is about 10 to 20%, after moderate injury 1 to 4%, and after mild injury is only marginally higher than baseline. It accounts for about 5% of epilepsy.

Risk factors: penetrating injury, depressed fracture, subdural, intracerebral or contusional haemorrhage, loss of consciousness for over 24 hours, age over 65 years, early seizures, and alcohol misuse.

Pathophysiology. Haemosiderin deposition, gliosis, inflammation and altered synaptic networks form an epileptic focus after a latent period (most occur within 2 years).

Focal seizures (with or without impaired awareness) or generalised tonic clonic seizures, often emerging months to years after injury, with frequent drug resistance. Cognitive and psychiatric problems are common.

Red flags.

• Status epilepticus or rapid seizure clustering.
• Late seizure with a new neurological deficit (consider abscess, hydrocephalus or haematoma).

Clinical history linking the injury to seizures. MRI with susceptibility weighted imaging shows contusions and haemosiderin, and CT shows haemorrhage, fracture or encephalomalacia. EEG shows focal slowing and epileptiform discharges. Exclude alcohol, drug withdrawal, metabolic disturbance, infection and psychogenic non-epileptic seizures.

Differential diagnosis.

• Psychogenic non-epileptic seizures, syncope and post-concussion symptoms.
• Alcohol related seizures, central nervous system infection and subdural haematoma.
• Sleep disorder.

Early prophylaxis. For moderate or severe injury, give levetiracetam 500 to 1000 mg twice daily (or phenytoin 15 to 20 mg/kg IV load then 5 mg/kg daily) for the first 7 days to reduce early seizures. Prolonged prophylaxis does not prevent epilepsy and is not advised beyond 7 days.

After a late seizure. Start long term treatment, because recurrence exceeds 80%. Levetiracetam 500 mg twice daily, increased to 1500 mg twice daily (adjust to eGFR), lamotrigine, lacosamide or carbamazepine, using usual doses. Consider cognitive and mood effects of drugs.

Drug resistance. Presurgical evaluation for a focal lesion, vagus nerve stimulation or responsive neurostimulation.

Other care. Treat sleep disorder, depression and post-traumatic headache, and give rehabilitation and cognitive support. Avoid alcohol.

Safety and driving. Advise on safety and local licensing rules.

Monitoring. Seizure diary, drug levels and neuropsychological review.

Referral and escalation. Refer to neurology and a rehabilitation service. Refer to epilepsy surgery if drug resistant.