A 16 year old male was admitted to rehabilitation following a two week stay in an acute care facility. He had been hit by a car while inline skating home from school (the teenager was not wearing a helmet). The patient underwent a craniotomy shortly after admission to hospital.
At the time of injury-while being treated at the scene-the patient underwent a seizure lasting 3 minutes. Tests indicate there was an electrolyte disturbance. Patient had been previously diagnosed with ADHD and had been receiving 5 mg of Ritalin (BID). To control for seizures the patient was originally administered phenytoin (25 mg BID). Just prior to the patient being admitted to rehab carbamazapine was then prescribed as his seizures continued.
8.1 Post-Traumatic Seizures
8.1.1 Classification of Post-Traumatic Seizures and Epilepsy
Define the following terms: Seizure, Post-traumatic Seizure and Epilepsy.
Seizure: Discrete clinical events that reflect a temporary physiologic dysfunction of the brain characterized by excessive and hypersynchronous discharge of cortical neurons.
Post-Traumatic Seizure: An initial or recurrent seizure episode not attributable to another obvious cause after penetrating or nonpenetrating TBI. The term post-traumatic seizure is preferred over post-traumatic epilepsy because the former encompasses both single and recurrent events.
Post-Traumatic Epilepsy: A disorder characterized by recurrent late seizure episodes not attributable to another obvious cause in patients following TBI. Although the term post-traumatic epilepsy commonly has designated single or multiple seizures including early seizures, the term should be reserved for recurrent, late PTS.
8.1.2 Identification of the “High-Risk” Patient
What factors are predictive of an ABI patient at high risk of seizures?
Patient characteristics: age, alcohol use, family history.
Injury Characteristics: Bone/metal fragments, depressed skull fracture, focal contusions/injury, focal neurological deficits, dural penetration, intracranial hemorrhage, more severe injury.
- Early post-traumatic seizures.
It is important to identify patients who are at high-risk of developing post-traumatic seizures (PTS)since these patients would benefit greatly from its prevention or from the impediment of its possible reoccurrence.
- There are several patient and injury characteristics that increase the likelihook for the development of late PTS.
1. Increasing age
2. Premorbid alcohol abuse
3. Family history
In terms of injury characteristics, markers of increasing injury severity such as penetrating injuries and depressed skull fracture increase the risks of late PTS.
A seizure occurring immediately after the injury substantially increases the risk of late PTS.
As the severity of brain injure increases, the period of time for which a survivor is at risk of developing PTS also increases.
- Yablon and Dostrow1 have proposed that methods that assess the clinical characteristics of the patient, the injury, and information obtained from neuroimaging and electrophysiologic assessment techniques can be used to identify such high-risk patients.
8.1.3 Natural History of Post-Traumatic Seizures
Describe the natural history of post-traumatic seizures.
55-67% of PTS patients will experience seizure within the first 12 months and 75-80% by the end of the second year.
Patients with moderate to severe TBI or penetrating TBI remain at increased risk for more than 5 years post TBI.
- Approximately half of those subjects with PTS will experience a seizure recurrence.
One-half to two-thirds of patients who suffer PTS will experience seizure onset within the first 12 months, and 75-80% will have seizures by the end of the second year following the injuryaccording to 1-4.
Patients with moderate or severe TBI or penetrating TBI remain at increased risk for more than 5 years post-injury 3;5-7.
Seizure recurrence is an important factor in the determination of disability, employment likelihood, quality of life, and increased health care costs 1;8;9.
- Some studies have reported that following early seizures post-TBI, only one-half of the patients experienced a recurrence 10;11while another quarter experienced a total of only 2-3 seizures 11.
8.1.4 Complications of Post-Traumatic Seizures
List some of the complications of post-traumatic seizures.
1. Deterioration in cognitive and behavioural functioning.
2. Deterioration in overall functional status.
3. Negative impact on neurological recovery.
4. Status epilepticus.
Seizures following TBI may themselves be a source of significant complications and morbidity 12
- The recurrence of seizures is an important cause of nonelective hospitalization in patients with severe TBI 12.
Cognitive and Behavioral Function
Post-traumatic seizure disorders may lead to cognitive and behavioural disorders1.
- Patients with PTS experience persistent behavioral abnormalities and a higher incidence of psychiatric-related hospitalizationseven compared with patients with penetrating TBI who do not experience PTS 13.
Influence on Neurologic Recovery
Post-traumatic seizures can influence neurological recovery 1;14.
- Severe and widespread seizures occurring within the first 6 days post brain injury can result in permanent impairments of functional recovery; while the same seizures occurring after the 6 day mark result in no change in somatosensory recovery14.
Recurrent PTS may exert a negative impact on functional status following TBI, an adverse effect independent of the severity of the injury15;16.
In the case of penetrating traumatic brain injuries, post-traumatic seizures have been reported to be an important and independent factor which affects both employment status and cognitive performance16.
- In the case of nonpenetrating TBI, the impact of PTS on functional prognosis and cognition is less clear 17;18.
Status epilepticus can be defined as either more than 30 minutes of continuous seizure activity1or two or more sequential seizures without full recovery of consciousness between seizures 19.
Status epilepticus is regarded as the most serious of the complications of PTS and may actually lead to additional neurological damage.
- Fortunately, clinically apparent status epilepticus is an infrequent complication of PTS 11.
Among patients with PTS mortality remains consistently elevated 1.
- The contribution of PTS to increased morality is unclearand some studies have suggested that deaths among penetrating TBI patients with PTS are due to complications of the actual injury and are not related to seizures 20;21.
For a more detailed discussion please see ERABI/Post- Traumatic Seizure Disorder.
8.1.5 Seizure Prevention or Prophylaxis
What evidence is there to support the prophylactic use of anticonvulsants after ABI?
Based on meta-analysis and the findings of this review there is Level 1 evidence that anticonvulsants given during the first 24 hours post-ABI reduce the occurrence of early seizures (within the first week post-injury).
- There is Level 1 evidence that anticonvulsants given shortly after the onset of injury, do not reduce mortality or persistent vegetative state or the occurrence of late seizures (> one week post-injury).
Most published randomized control trials have failed to find any favorable evidence for prophylaxis of late PTS22-25.
In some of these reports, the occurrence of PTS was actually higher in patients treated with anticonvulsant medications 24-27.
Anticonvulsant drug prophylaxis consistently reduces the incidence of early PTS1.
Similar to most of the studies on late PTS, there is no evidence that anticonvulsant drug prophylaxis of early seizures reduces the occurrence of late PTS or has any effect on mortality or neurologic disability 28.
Patients who suffer severe penetrating brain injuries experience higher risks of PTS.
- However, due to the small number of patients with penetrating TBI in most reports, it is not clear if anticonvulsant drug prophylaxis has any effect, on the occurrence of PTS is this subgroup of brain injury patients.
For a greater discussion on the treatment of seizures post ABI please ERABI/Post Traumatic Seizure Disorder.
Does methylphenidate used for the treatment of cognitive and behavioural problems post ABI increase the risk of seizures?
- There is Level 4 evidence that methylphenidate for the treatment of cognitive and behavioral problems can be safely used in brain injured patients at risk for posttraumatic seizures as it is not associated with an increase in seizure frequency.
What concerns are there for the use of anticonvulsants on rehabilitation? What evidence is there for this?
- There is Level 1 evidence that both phenytoin and carbamazepine have negative effects on cognitive performance, particularly on tasks with motor and speed components, which theoretically may have a negative impact upon learning during rehabilitation.