The Value of Diagnostic Persistence
Dr. Gregory Krauss has been a faculty member of the Department of Neurology since July 1991. He is Associate Professor of Neurology with specialization in the evaluation and treatment of seizures and epilepsy.
The Value of Diagnostic Persistence
By Gregory L Krauss
The patient is a 26-year-old right-handed woman with a history of complex partial seizures beginning at approximately 1 year of age. She typically had one or two complex partial or secondary generalized seizures every morning with as many as 50–60 seizures in one day. She became aware of her seizures at the age of 5, describing ‘weird feelings in her head’ followed by a scared look, and then her head and eyes would roll back with stiffening and shaking.
Several routine EEGs were normal. Her seizures failed to respond to all available antiepileptic drugs. During video-EEG monitoring at the age of 16, she had diffuse anterior hemispheric seizure onset, maximal on the left, as well as numerous psychic sensations that were unaccompanied by EEG changes. She was thought to have a mixed disorder with seizures and pseudoseizures or some seizures that did not project to the surface. Magnetic resonance imaging (MRI) scanning was normal. She failed additional treatment with methsuximide, vigabatrin and clorazepate maximized to 18.75 mg/day. She had an occipital hemorrhage as a result of a seizure-related head injury at the age of 26. She had a positive antinudear antibody secondary to phenytoin. She had ovarian cysts, possibly associated with her antiepileptic drugs. She also had an episode of serial seizures that required several days of barbiturate coma therapy with airway intubation.
Examination and investigations
The patient’s neurological and general examinations were normal. At the age of 21, additional video-EEG monitoring was performed. Interictally there were frequent spike and sharp waves that were widely distributed over the anterior midline and frontal regions bilaterally. Spikes were sometimes slightly maximum on the left. She had 22 seizures during 4 days of monitoring, including two secondary generalized seizures. These secondary generalized seizures began with eye opening and then staring and chewing followed by fast hyperventilation with pursed lips. These seizures were poorly localized with widely distributed bilateral frontal spikes, maximal over the midline, followed by generalized slowing. Four seizures that occurred after medication withdrawal showed an anterior midline spike pattern followed by generalized electrodecremental pattern and then generalized slowing.
Several months later, the patient underwent depth electrode seizure recording. She had electrode tresses placed bilaterally superiorally in the frontal lobes, with additional electrodes projecting into amygdala and hippocampus. During her seizures there were no ictal patterns recorded on the depth electrodes.
The patient was offered several options: vagal nerve stimulation, anterior callosal sectioning to stop secondary generalized seizures and lateralize her seizures, experimental medications and additional intracranial monitoring.
She received investigational treatment with felbamate, but continued to have several seizures a day. Three years after her unsuccessful depth electrode monitoring, the patient had additional intracranial seizure monitoring. She had subdural strips placed bilaterally, with four 1 × 8 cm strips placed over each anterior frontal lobe. She also had a 2 × 8 cm electrode grid placed over the saggital midline with bilateral electrodes. These electrodes covered the anterior medial frontal lobe, including the cingulate cortex. The patient had nine complex partial seizures, of which seven were secondarily generalized. Six of these seizures were well localized to the right medial frontal and right anterior lateral frontal lobe with an anterior cingulate seizure maximum. She also had two clinically atypical partial seizures beginning from the left frontal lobe.
Right anterior cingulate and anterior lateral frontal lobe seizures.
Treatment and outcome
The patient tolerated resective surgery well. Preoperatively she had between two and four complex partial and secondary generalized seizures a day. Since surgery she has been free of seizures for the past 6 years. Because she had two clincally atypical seizures originating from the left anterior frontal lobe during intracranial recording, she has continued on carbamazepine 600 mg four times daily. Before surgery she had been a very pleasant but insecure young woman who, despite her uncontrolled epilepsy, walked to work several miles each day and frequently had seizures on the roadside. She is now able to be employed full time and is engaged to be married.
The patient had extremely difficult-to-control complex partial and secondary generalized seizures that were life-long and not associated with MRI changes. She attempted to work despite daily seizures. She was very shy, lacked confidence and was socially impaired as a result of her episodes. Over the years it was felt that some of her episodes could have been pseudoseizures, but in fact these were partial seizures beginning in the frontal lobe. The patient had poorly localized seizures on initial scalp video-EEG recording and had several additional years of additional medication trials with no benefit before her surgery.
The patient then had scalp monitoring with extra recording electrodes and had a large number of seizures that showed a frontal midline seizure onset. This detailed scalp recording allowed effective intracranial mapping using subdural electrode strips to be performed.
The majority of patients with extratemporal epilepsy and no structural lesions are reported to do poorly with epilepsy surgery. This patient, however, became seizure-free after right anterior cingulate and lateral frontal resection.
What did I learn from this case?
This case illustrates the difficulty of localizing seizures in extratemporal neocortex. It also highlights the possibility that some patients with uncontrolled but stereotyped seizures may have focal ictal zones and may benefit from surgical treatment.
How did this case alter my approach to the care and treatment of my epilepsy patients?
Patients whose seizures fail to respond to several standard antiepileptic drugs at high doses are unlikely to become seizure-free on newer drugs. In this patient, surgery had a remarkably beneficial effect on her life.
Patients with non-lesional extratemporal epilepsy are reported to be poor candidates for surgery. This case demonstrates, however, that some patients with frontal lobe seizures, particularly if the seizures are localized to medial frontal areas, may be good candidates for surgery. Patients with frontal lobe seizures often have diffuse ictal EEG patterns, owing to rapid seizure propagation and sometimes to large areas of cortex being involved. This patient, however, had a diffuse anterior seizure onset with a midline maximum and, in fact, turned out to have anterior cingulate involvement on intracranial mapping. Her case illustrates the importance of effective sampling using intracranial electrodes. The patient had no seizures localized with depth electrodes placed through the superior lateral frontal lobes but had discrete seizure localization with bilateral subdural electrode strips and grids.
Williamson PD. Frontal lobe seizures: problems of diagnosis and classification. In: Chauvel P, Delgado-Escueta AV, Halgren E, Bancand J. Frontal lobe seizures and epilepsy. Advances in neurology, vol 57. New York: Raven; 1992.
This selection for "Challenging Cases" is from 110 Puzzling Cases of Epilepsy, edited by Dieter Schmidt, MD, and Steven C. Schachter, MD (Martin Dunitz, Publisher, London, 2002).
Topic Editor: Steven C. Schachter, MD
Submitted on 05/26/07
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