Impaired consciousness in partial seizures is bimodally distributed
Courtney Cunningham1, William C Chen, Andrew Shorten
1From the Departments of Neurology (C.C., W.C.C., A.S., M.M., T.C., C.P.S., V.C., A.B., C.B., M.C., M.F., K.D., H.B.), Neurobiology (H.B.), and Neurosurgery (H.B.), Yale University School of Medicine, New Haven, CT; and Department of Physical Medicine and Rehabilitation (J.T.G.), Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA.
Neurology
|April 15, 2014
Summary
Partial seizures often cause either full impairment or no impairment in consciousness, unlike brain injuries which show varied impairment levels. This suggests seizures uniquely affect overall arousal and thalamocortical function.
Area of Science:
- Neuroscience
- Clinical Neurology
- Epilepsy Research
Background:
- Impaired consciousness during partial seizures is common.
- The nature of this impairment (specific deficits vs. general decrease) remains unclear.
Purpose of the Study:
- To determine if impaired consciousness in partial seizures involves specific content deficits or a general decrease in arousal.
- To compare responsiveness patterns in partial seizures with those in traumatic brain injury.
Main Methods:
- Prospective testing using the Responsiveness in Epilepsy Scale during 83 partial seizures in 30 epilepsy patients.
- Comparison with responsiveness scores from 552 test administrations in 184 traumatic brain injury patients using the JFK Coma Recovery Scale-Revised.
Main Results:
- Partial seizures exhibited a bimodal responsiveness distribution: either fully impaired or relatively spared.
- Impairment during seizures was consistent across cognitive tests.
- Traumatic brain injury patients showed a wider, more even distribution of impairment severity.
Conclusions:
- Partial seizures often present with either complete or no overall impairment in responsiveness.
- The bimodal pattern in epilepsy appears distinct from the varied impairment seen in brain injury.
- Findings support a model where seizures either spread to or avoid brain regions regulating arousal and thalamocortical function.
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