What are the peri‑operative considerations for a patient with a seizure disorder undergoing total knee replacement?

Perioperative Management of Seizure Disorder in Total Knee Replacement

Continue all antiseizure medications (ASMs) through the morning of surgery without interruption, as abrupt discontinuation risks breakthrough seizures and status epilepticus, which carries significant morbidity and mortality risk. 1

Preoperative Optimization

Medication Management

• Maintain therapeutic ASM levels throughout the perioperative period
• Administer morning dose of ASMs on day of surgery with small sip of water
• Verify therapeutic drug levels preoperatively for medications requiring monitoring (phenytoin, valproic acid, carbamazepine)
• Do NOT use prophylactic ASMs if the patient has never had a seizure—this applies only to neurosurgical procedures, not orthopedic surgery 2

Critical Preoperative Assessment

Document the following seizure-specific details:

• Seizure frequency and last seizure date (recent seizures increase perioperative risk)
• Seizure type and triggers (sleep deprivation, stress, metabolic disturbances)
• Current ASM regimen, adherence, and recent changes
• History of status epilepticus (highest risk patients)
• Presence of drug-resistant epilepsy (one-third of patients)

Risk Stratification

Patients with epilepsy undergoing total knee arthroplasty face significantly elevated risks 3, 4:

• 2.03-fold increased mortality (OR 2.03,95% CI 1.57-2.62)
• 1.74-fold increased risk of mechanical ventilation
• 1.70-fold increased risk of induced mental disorder
• 1.29-fold increased risk of prosthetic joint infection after TKA
• 2.19-fold increased risk of low-energy falls within 2 years after TKA

Anesthetic Considerations

Agent Selection

Avoid or use with extreme caution:

• Ketamine (lowers seizure threshold, can precipitate seizures)
• Etomidate (epileptogenic, contraindicated)
• Enflurane (epileptogenic, avoid)
• Methohexital (activates seizure foci)

Safe choices:

• Propofol (anticonvulsant properties, preferred induction agent)
• Sevoflurane/Desflurane (safe maintenance agents)
• Benzodiazepines (midazolam has anticonvulsant effects)
• Opioids (fentanyl, remifentanil are seizure-neutral)

Regional vs. General Anesthesia

Neuraxial anesthesia (spinal/epidural) is preferred when feasible for total knee arthroplasty, as it:

• Avoids potential seizure-provoking general anesthetic agents
• Reduces risk of aspiration if seizure occurs
• Allows continued consciousness for seizure detection
• However, general anesthesia is acceptable with appropriate agent selection 5

Perioperative Medication Transitions

NPO Period Management

For patients unable to take oral medications:

• Convert to IV formulations when available (levetiracetam, valproic acid, phenytoin/fosphenytoin)
• Levetiracetam IV: same dose as oral, given over 15 minutes
• Fosphenytoin IV: 15-20 mg PE/kg loading dose if needed
• Valproic acid IV: same total daily dose divided q6-8h

Drug Interactions—Critical

Enzyme-inducing ASMs (phenytoin, carbamazepine, phenobarbital) significantly alter metabolism of:

• Perioperative steroids (dexamethasone)
• Anticoagulants (warfarin, DOACs)
• Opioids (reduced efficacy)

Non-enzyme-inducing ASMs preferred (levetiracetam, valproic acid, lamotrigine) to avoid these interactions 2, 6, 2

Valproic acid warning: Associated with thrombocytopenia and hepatotoxicity; check platelet count preoperatively if on valproic acid 2

Pain Management Modifications

Multimodal Analgesia

Strongly recommended 7:

• COX-2 selective NSAIDs (celecoxib)—strong evidence for limiting opioid use
• Acetaminophen (oral preferred over IV; no difference in efficacy, lower cost)
• IV ketamine in perioperative period—use with caution in epilepsy patients due to potential seizure provocation

Gabapentin/Pregabalin:

• No significant benefit demonstrated for pain or opioid reduction in TKA 7
• May cause sedation and dizziness, increasing fall risk (already elevated 2.19-fold in epilepsy patients)
• Not recommended for routine use in this population

Intraoperative Seizure Management

If seizure occurs during surgery:

1. Protect airway immediately—intubate if not already secured
2. Administer benzodiazepine: midazolam 0.1-0.2 mg/kg IV or lorazepam 0.1 mg/kg IV 8
3. Avoid propofol if cardiovascular instability present 8
4. Check glucose, electrolytes (hypoglycemia, hyponatremia common triggers)
5. Load with IV ASM if subtherapeutic levels suspected
6. Abort procedure if status epilepticus develops—transfer to ICU

Postoperative Management

Immediate Recovery

• Resume oral ASMs as soon as patient tolerates PO
• Continue IV formulations until oral route established
• Monitor for breakthrough seizures for 48-72 hours (highest risk period)
• Avoid sleep deprivation (common seizure trigger)

Fall Prevention Protocol—Essential

Given 14.1% fall rate within 2 years after TKA in epilepsy patients 4:

• Bed alarm and 1:1 observation if recent seizures or high-risk
• Physical therapy evaluation before discharge
• Home safety assessment and assistive devices
• Avoid sedating medications (opioids, benzodiazepines) when possible

Discharge Planning

• Verify therapeutic ASM levels before discharge
• Provide written seizure action plan
• Coordinate with neurologist for follow-up within 1-2 weeks
• Counsel on increased infection risk (1.29-fold) and need for vigilance for wound complications 4

Key Pitfalls to Avoid

1. Never discontinue ASMs perioperatively—withdrawal seizures can be fatal
2. Never use prophylactic ASMs in epilepsy patients without active seizures (no benefit, 18% adverse event rate) 2
3. Never assume seizure control is adequate—verify recent levels and seizure frequency
4. Never discharge without fall prevention counseling—falls are the most common complication
5. Never use ketamine without careful consideration—can precipitate seizures despite analgesic benefits