Cefepime Encephalopathy and Muscle Twitch
Yes, cefepime-induced encephalopathy commonly causes myoclonus (muscle twitching), which occurs in approximately 42% of patients experiencing neurotoxicity. 1
Clinical Manifestations of Cefepime Neurotoxicity
Cefepime neurotoxicity presents with a constellation of neurological symptoms, with muscle-related manifestations being prominent:
- Myoclonus (muscle twitching/jerking) occurs in 42% of cases and represents one of the most common manifestations alongside altered mental status 1
- Reduced consciousness occurs in 47% of patients 1
- Confusion is present in 42% of cases 1
- Other manifestations include encephalopathy, seizures, aphasia, and in severe cases, coma 2, 1
- Orofacial myokymia (facial muscle twitching) has been specifically documented 3
- Neuromuscular excitability is an established feature of overdose 2
Mechanism
Cefepime crosses the blood-brain barrier and exhibits concentration-dependent GABA (gamma-aminobutyric acid) antagonism, which explains the neurotoxic symptoms including myoclonus 1, 4. Cefepime has the second-highest pro-convulsive activity among beta-lactams at 160% compared to penicillin G 5, 6.
Risk Factors
- Renal dysfunction is present in 80% of cases, making it the primary risk factor due to drug accumulation 1
- Neurotoxicity can occur despite appropriate renal dose adjustment in 26% of patients 6, 1, 3
- Preexisting brain injury increases risk 1
- Advanced age and metabolic encephalopathy from chronic uremia increase sensitivity 7
- History of stroke or seizures 3
Diagnostic Findings
- All patients with EEG testing (98 patients, 73% of cohort) showed abnormalities 1
- Triphasic waves occur in 40% of cases 1
- Non-convulsive status epilepticus in 25% 1
- Myoclonic status epilepticus in 7% 1
- Focal sharp waves in 39% 1
- Cefepime trough concentrations above 22 mg/L or steady-state concentrations above 35 mg/L are associated with neurotoxicity in 50% of patients 6
- Median serum concentration in toxic patients was 45 mg/L 1
Management
Immediate discontinuation of cefepime is the definitive treatment 6, 8, 1:
- Symptom improvement occurs in 89% of patients after intervention 1
- Median time from symptom onset to resolution is 2 days after cefepime discontinuation 1
- Complete resolution of mental status typically occurs within 24-72 hours 4, 3
- 87% of patients survive to hospital discharge 1
Aggressive treatment with anti-seizure medications is not warranted 8. While benzodiazepine trials may temporarily improve EEG findings, they do not address the underlying cause 8.
Hemodialysis should be considered to aid removal of cefepime from the body, particularly in patients with renal impairment 2, 7. Peritoneal dialysis is not recommended 2.
Common Pitfall
48% of patients were overdosed according to FDA-approved dosing guidance, but critically, 26% experienced neurotoxicity despite appropriate renal dose adjustment 1, 3. This means you cannot rely solely on proper dosing to prevent this complication—vigilant monitoring for neurological symptoms is essential in all patients receiving cefepime, especially those with renal dysfunction or other risk factors.