Posttraumatic seizure (PTS) and posttraumatic epilepsy (PTE) are potential complications of traumatic brain injury (TBI). PTS is defined as a single seizure resulting from head trauma in exclusion of other causes. PTE is defined as a posttraumatic recurrent seizure disorder with each event being separated by more than 24 hours. For clarification purposes, when referring to TBI in this chapter, the author is not including concussion.
Classification
PTS types include :
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Generalized seizures (other terms include grand mal or tonic–clonic seizures when there is motor involvement or absence seizures when there is not)
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Focal seizures without or with alteration of consciousness and awareness (other terms are simple partial and complex partial seizures , respectively)
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Focal seizures can progress to generalized seizures (secondary generalization).
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Most PTS are the focal seizure type (partial) , ,
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PTS is classified temporally as , , :
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Immediate (occurring within 24 hours posttrauma)
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Early (between 24 hours and 1 week posttrauma)
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Late (after 1 week posttrauma)
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Epidemiology
Incidence rates of immediate, early, and late PTS are 1% to 4%, 4% to 25%, and 9% to 42%, respectively. Depending on TBI severity, 2% to 50% of patients may develop PTE. In the general population, for 10% to 20% of patients with symptomatic epilepsy, it is attributed to PTE. , , Eighty-percent of patients with PTE have their first seizure within 1 year postinjury, 90% within 2 years postinjury. Patients with moderate or severe TBI are at increased risk for seizures for 10 to 20+ years postinjury. ,
Risk factors for late-onset posttraumatic epilepsy
PTE probability within 5 years postinjury depends on TBI severity: mild TBI (0.7%), moderate TBI (1.2%), severe TBI (10%). Late-onset PTE risk factors include , , :
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Injury type/location: Biparietal contusions (66%), dural penetration with fragments (62.5%), multiple intracranial operations (36.5%), subcortical contusions (33.4%), evacuated subdural hematoma (27.8%), greater than 5 mm midline shift (25.8%), multiple or bilateral cortical contusions (25%)
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Depressed skull fracture
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Loss of consciousness longer than 30 minutes
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Posttraumatic amnesia longer than 24 hours
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Early PTS
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Alcohol
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Increasing age: Adolescents and adults at higher risk than children.
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Genetics
Pathophysiology
The pathophysiology of PTS and PTE is an area of ongoing research. , , Multiple mechanisms have been proposed for PTS. Immediate or early PTS is thought to result from TBI primary injury and late PTS from secondary injury. Seizures result in increased intracranial pressure and neurometabolic demand and can lead to further neurologic injury.
Diagnosis
Making the diagnosis of PTE can be challenging. Depending on the type and location of seizures, the presentation of patients with PTE can range from diffuse tonic–clonic movements to subtle, repetitive alterations in sensation, cognition, and behavior (i.e., partial seizures). Patient signs and symptoms may overlap with other diagnoses, so it is important to approach workup carefully. Although there are diagnostic testing options, the diagnosis of PTE is ultimately made on a clinical basis.
Diagnostic tests
Consider workup of other medical issues (e.g., acute intracranial process, electrolyte abnormality, infection).
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Electroencephalogram (EEG): Types include standard, sleep, sleep-deprived, ambulatory, or video-monitored. Of the different testing options, video-EEG monitoring is the gold standard. There are limitations to EEG testing. It has limited sensitivity to rule out seizures. It can result in normal findings. Additionally, depending on their neurobehavioral status, patients may not be able to cooperate with the procedure.
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Serum prolactin: Can be elevated after a seizure. This laboratory test could be used as an adjunct test to help differentiate between an epileptic and nonepileptic event, but a normal serum prolactin value does not rule out seizure.
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Consider neurology consult.
Treatment options
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Medication: Current guidelines are to treat TBI patients with 7 days of antiepileptic drug (AED) for seizure prophylaxis. Long-term AED treatment is not recommended for patients with immediate PTS. Studies have not demonstrated efficacy in reduction of late-onset seizures or mortality with long-term AED treatment in the absence of early or late PTS. Patients who have early or late PTS are to be treated with AED long term. If stable from a seizure standpoint for at least 2 years, taper of AED could be considered. Superiority of individual AED agents in PTE has not been supported in studies. All AEDs, especially older agents such as phenytoin and phenobarbital, have potential for cognitive and motor side effects . In patients with neurocognitive issues, AED adverse effect should be considered in the differential diagnosis. Medication choice should be based on factors including side effect profile, potential drug-drug interactions, patient tolerability, dosing schedule, need for monitoring, and expected patient medication compliance. Female TBI patients with potential for pregnancy should be counseled on potential teratogenic effects of AEDs. Additionally, consider the potential therapeutic effects of individual AEDs (e.g., mood stabilization and migraine prophylactic effects of valproic acid). , ,
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Surgical: Consider neurosurgical consult. Although less extensively studied in the diagnosis of PTE, there are surgical options for patients with intractable epilepsy: Resection can be considered if a seizure focus or area can be localized. In cases in which the seizure foci cannot be localized, vagal nerve stimulator placement is another option, but this intervention is expected, at best, to decrease seizure frequency.
Driving and work
There is variation from state to state in how driving is managed in regards to epilepsy. Patients will need to be stable from a seizure standpoint for a period of time (typically ranging from 3–12 months) and have forms completed by their healthcare provider to request reinstatement of driving privileges by the state board. Restoration of a commercial driver’s license may be challenging because of restrictions on medications with potential psychotropic effects.
In regards to work, it is recommended that the employer obtain a comprehensive job description, along with potential for schedule or work accommodations, to maximize safety in returning to work.
Review questions
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A late posttraumatic seizure (PTS) occurs during which time frame?
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Within 24 hours
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Between 1 and 7 days
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After 1 week
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After 1 month
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A patient is admitted to the hospital after witnessed fall off a ladder onto his head with loss of consciousness and generalized tonic–clonic movements that resolved after a couple minutes. Head computed tomography (CT) reveals intraparenchymal hematoma without significant mass effect. How long should he be treated with an antiepileptic drug (AED)?
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No AED treatment is indicated
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1 week
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3 months
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1 year
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You are managing a patient in the acute rehabilitation TBI unit. She is presenting with intermittent periods of confusion and irritability manifested as shouting, pulling at lines, and aggression toward staff. This is interfering with her therapy program participation. Recent imaging and laboratory workup have ruled out acute intracranial process, electrolyte abnormality, and ongoing infection. Intermittent seizures are suspected. What is the next reasonable step in care?
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Clinically observe
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Order standard electroencephalogram (EEG)
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Order serum prolactin level
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Treat empirically with AED and monitor patient response
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Answers on page 394.
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After what time of treatment with AED for posttraumatic epilepsy (PTE) could medication taper be considered?
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2 years
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1 year
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6 months
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3 months
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In follow up at TBI clinic, your patient with diagnosed PTE asks about reinstating his driving license. He has been clinically stable on an AED for 4 months postinjury. What is the next step?
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Submit state forms requesting driver’s license restoration.
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Submit state forms requesting driver’s license restoration after 6 months postinjury.
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Submit state forms requesting driver’s license restoration after 9 months postinjury.
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Review local state regulations regarding driver’s license reinstatement requests for patients with PTE.
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References
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