# Status Epilepticus in the Neurosurgical Patient

## Introduction

Status epilepticus (SE) is a neurological emergency defined as continuous seizure activity lasting five minutes or longer, or two or more seizures without return to baseline between them. Neurosurgical patients are at elevated risk due to cortical irritation from craniotomy, tumors, hemorrhage, and infection. Both convulsive and non-convulsive forms must be recognized and treated aggressively, as prolonged seizures cause excitotoxic neuronal injury and worsen outcomes in an already vulnerable brain.

## Definitions and Classification

Convulsive status epilepticus (CSE) refers to generalized tonic-clonic activity persisting for five minutes or more. Non-convulsive status epilepticus (NCSE) involves electrographic seizure activity without overt motor manifestations and is diagnosed by continuous EEG monitoring. Refractory status epilepticus (RSE) is defined as seizures persisting despite two appropriately dosed antiseizure medications. Super-refractory status epilepticus (SRSE) describes seizures that continue for 24 hours or longer after initiation of anesthetic therapy, including cases where seizures recur during or after anesthetic taper.

## Neurosurgical Risk Factors

Several conditions common in neurosurgical patients predispose to status epilepticus. Post-craniotomy seizures occur most frequently with supratentorial surgery near eloquent cortex, with an incidence of 5 to 15 percent. Brain tumors are a major risk factor, as seizures are the presenting symptom in 30 to 50 percent of glioma patients, driven by peritumoral edema and cortical invasion. Intracranial hemorrhage of any type, including subarachnoid hemorrhage, intraparenchymal hemorrhage, and subdural hematoma, can provoke seizures. Traumatic brain injury carries risk for both early seizures (within seven days) and late seizures (beyond seven days), with penetrating injuries posing the highest risk. CNS infections such as abscess, meningitis, and encephalitis are additional risk factors, as is cerebral venous sinus thrombosis, which causes seizures in 30 to 40 percent of cases. Metabolic derangements commonly encountered in post-neurosurgical patients, including hyponatremia, hypocalcemia, and hypoglycemia, can also trigger seizures.

## Clinical Assessment

### Recognition

Convulsive SE presents with rhythmic jerking, tonic posturing, and eye deviation, though it may evolve to subtle motor manifestations as the episode progresses. Non-convulsive SE is more insidious, presenting as unexplained altered consciousness, subtle eye movements, automatisms, or fluctuating levels of awareness in a neurosurgical patient. Studies show that 10 to 35 percent of comatose neurocritical care patients have non-convulsive seizures detected on continuous EEG. Clinicians should always consider NCSE when a patient fails to improve neurologically as expected after surgery or injury.

### Evaluation

Continuous EEG monitoring is essential for diagnosing NCSE and monitoring treatment response. Point-of-care glucose testing should be performed immediately, as hypoglycemia is a treatable cause. Electrolytes including sodium, calcium, and magnesium should be checked, along with antiseizure medication levels if the patient was on prior therapy. Emergent CT of the head is needed to rule out new hemorrhage, mass effect, hydrocephalus, or infarction. A toxicology screen is appropriate if ingestion is suspected.

![EEG patterns in convulsive and non-convulsive status epilepticus](illustration-se-eeg-patterns.jpg)

## Treatment Algorithm

### Stage 1: Emergent Therapy (0-5 minutes)

Benzodiazepines are the first-line treatment. Lorazepam is given at 0.1 mg/kg IV, with a maximum of 4 mg per dose, and may be repeated once. If IV access is not available, midazolam 10 mg IM is an alternative, or 0.2 mg/kg IV if access is established. Diazepam at 0.15 mg/kg IV (maximum 10 mg) is another option but has a shorter duration of antiseizure effect. Simultaneously, the ABCs should be stabilized, the patient placed in a recovery position if not intubated, and SpO2 monitored. IV dextrose should be given if glucose is below 60 mg/dL, and thiamine 100 mg IV administered if nutritional deficiency is suspected.

### Stage 2: Urgent Therapy (5-20 minutes)

If seizures persist after benzodiazepines, a second-line antiseizure medication should be initiated. Options include levetiracetam at 60 mg/kg IV (maximum 4,500 mg) over 15 minutes, fosphenytoin at 20 mg PE/kg IV at 150 mg PE/min (avoiding patients with cardiac conduction abnormalities), valproic acid at 40 mg/kg IV (maximum 3,000 mg) over 10 minutes (avoiding hepatic disease, pregnancy, and mitochondrial disease), and lacosamide at 400 mg IV over 15 minutes, which has fewer drug interactions and is generally well tolerated. The ESETT trial demonstrated that no single second-line agent has proven superiority, with levetiracetam, fosphenytoin, and valproate each achieving similar efficacy at approximately 45 to 50 percent.

| Stage | Timing | Agent | Dose | Key Consideration |
|-------|--------|-------|------|-------------------|
| 1 (Emergent) | 0-5 min | Lorazepam | 0.1 mg/kg IV (max 4 mg) | First-line; repeat once |
| 1 (Emergent) | 0-5 min | Midazolam (no IV) | 10 mg IM | Alternative if no IV access |
| 2 (Urgent) | 5-20 min | Levetiracetam | 60 mg/kg IV (max 4,500 mg) | Fewest drug interactions |
| 2 (Urgent) | 5-20 min | Fosphenytoin | 20 mg PE/kg IV | Avoid cardiac conduction disease |
| 2 (Urgent) | 5-20 min | Valproic acid | 40 mg/kg IV (max 3,000 mg) | Avoid hepatic disease, pregnancy |
| 3 (Refractory) | >20 min | Midazolam infusion | 0.2 mg/kg bolus → 0.1-2 mg/kg/hr | Intubation + cEEG required |
| 3 (Refractory) | >20 min | Propofol | 1-2 mg/kg → 20-80 mcg/kg/min | Monitor for PRIS |
| 3 (Refractory) | >20 min | Pentobarbital | 5-15 mg/kg → 0.5-5 mg/kg/hr | Most reliable burst suppression |

### Stage 3: Refractory SE (>20-30 minutes)

At this stage, intubation and ICU admission with continuous EEG monitoring are required. Anesthetic therapy is initiated with continuous infusion. Midazolam can be given as a 0.2 mg/kg bolus followed by 0.1 to 2 mg/kg/hr infusion. Propofol is administered as a 1 to 2 mg/kg bolus followed by 20 to 80 mcg/kg/min, with monitoring for propofol infusion syndrome. Pentobarbital, given as a 5 to 15 mg/kg bolus followed by 0.5 to 5 mg/kg/hr, most reliably achieves burst suppression but causes significant hypotension. The EEG target is seizure suppression or a burst-suppression pattern, and the anesthetic infusion should be maintained for 24 to 48 hours before gradual taper.

### Stage 4: Super-Refractory SE

When seizures persist or recur during or after anesthetic taper, additional agents must be considered. Ketamine, an NMDA receptor antagonist, is given as a 1 to 2 mg/kg bolus followed by 1 to 5 mg/kg/hr infusion and complements GABAergic agents through a different mechanism of action. Other options include inhaled anesthetics such as isoflurane, magnesium infusion, therapeutic hypothermia at 32 to 35 degrees Celsius, and immunotherapy if an autoimmune etiology is suspected. Evaluation for autoimmune encephalitis, including anti-NMDA receptor, LGI1, and CASPR2 antibodies, should be undertaken if no structural cause is identified. In neurosurgical patients, focal resection or disconnection may be considered for refractory SE when an identifiable focal epileptogenic lesion exists.

![Stepwise treatment algorithm for status epilepticus](illustration-se-treatment-algorithm.jpg)

## Neurosurgery-Specific Considerations

### Seizure Prophylaxis in Neurosurgical Patients

For traumatic brain injury, prophylactic levetiracetam or phenytoin for seven days reduces early seizures but does not prevent the development of late epilepsy. In craniotomy for tumors, prophylaxis is controversial, and AAN guidelines recommend against routine prophylaxis in patients without prior seizures. After subarachnoid hemorrhage, short-term prophylaxis for three to seven days is reasonable, though prolonged use is associated with worse outcomes. For brain abscess, seizure prophylaxis is recommended given the high seizure risk of approximately 50 percent.

### Impact on ICP

Seizures significantly increase cerebral metabolic rate and intracranial pressure. In patients with compromised intracranial compliance, status epilepticus can precipitate herniation. Aggressive seizure control is therefore essential in patients with ICP monitors showing elevated pressures. Continuous EEG monitoring should be considered in all patients with external ventricular drains and unexplained ICP elevations.

## Complications of Status Epilepticus

Prolonged status epilepticus leads to numerous systemic and neurological complications. Excitotoxic neuronal injury results from sustained glutamate release. Rhabdomyolysis from prolonged motor activity necessitates monitoring of creatine kinase and renal function. Aspiration pneumonia is a risk, making airway protection essential. Cardiac arrhythmias may occur from catecholamine surge and direct autonomic effects. Metabolic acidosis develops from lactic acid production during sustained muscle activity. Mortality is 15 to 20 percent for convulsive SE and higher for refractory and super-refractory forms.

![Complications of prolonged status epilepticus](illustration-se-complications.jpg)

## Clinical Pearls

Non-convulsive status epilepticus is a hidden cause of unexplained impaired consciousness in neurosurgical patients, and continuous EEG is required for diagnosis. Benzodiazepines remain first-line therapy, with lorazepam IV preferred for its longer duration of antiseizure effect compared to diazepam. The ESETT trial showed equivalent efficacy of levetiracetam, fosphenytoin, and valproate as second-line agents, allowing choice based on patient-specific factors such as comorbidities and drug interactions. Seizure prophylaxis after TBI should be limited to seven days, as it prevents early seizures but does not reduce the development of post-traumatic epilepsy. In patients with elevated ICP, seizures can be catastrophic, making aggressive treatment and continuous EEG monitoring mandatory.

## References

1. Kapur J, Elm J, Chamberlain JM, et al. Randomized trial of three anticonvulsant medications for status epilepticus (ESETT). *N Engl J Med*. 2019;381(22):2103-2113.
2. Brophy GM, Bell R, Claassen J, et al. Guidelines for the evaluation and management of status epilepticus. *Neurocrit Care*. 2012;17(1):3-23.
3. Temkin NR. Preventing and treating posttraumatic seizures: The human experience. *Epilepsia*. 2009;50(Suppl 2):10-13.
4. Claassen J, Mayer SA, Kowalski RG, et al. Detection of electrographic seizures with continuous EEG monitoring in critically ill patients. *Neurology*. 2004;62(10):1743-1748.