Neuropsychological outcome after epilepsy surgery in patients with bilateral Ammon's horn sclerosis

Abstract

Object. The purpose of this study was to retrospectively assess the objective and subjective neuropsychological outcome after epilepsy surgery in patients with bilateral Ammon's horn sclerosis (AHS).Methods. Memory and executive functions were evaluated at baseline and at follow-up in 11 surgically treated patients and compared with 8 pharmacologically treated patients with temporal lobe epilepsy and bilateral AHS. The median follow-up duration was 16 months in the surgically treated patients and 80.5 months in the pharmacologically treated group. Subjective outcome was evaluated by questionnaires and included mood, quality of life, subjective memory, and activities of daily living.Results. At the follow-up assessment, 82% of the surgically treated patients as opposed to 0% of the nonsurgery patients were seizure free. In the surgical group, nonverbal memory performance did not change significantly in any patient after surgery, but there was a floor effect in 55% of the surgical patients. Regarding verbal memory, 9% of the surgical patients improved while 73% declined, despite severe impairments already evident at baseline. In the nonsurgery control group, 13% of the patients declined in nonverbal memory (floor effect in 63%) and 25% declined in verbal memory (floor effect in 25%) at follow-up. None of the controls improved at follow-up. Executive functions remained unchanged on an impaired level in both groups. At follow-up, the patient groups did not differ significantly with respect to mood, quality of life, subjective memory, or activities of daily living. However, in most aspects, surgically treated patients reported a slightly better subjective outcome than pharmacologically treated patients and a significantly improved quality of life.Conclusions. These results suggest that beyond benefits concerning seizure control, surgically treated patients with bilateral AHS, despite already poor baseline performance, are still at risk for severe postoperative decline in memory. In the light of predominantly minor benefits on a subjective level, the findings put the overall outcome of epilepsy surgery in bilateral AHS patients into perspective. (http://thejns.org/doi/abs/10.3171/2014.7.JNS132037) key WordS • neuropsychological outcome • temporal lobe epilepsy surgery • memory • bilateral Ammon's horn sclerosis Abbreviations used in this paper: AHS = Ammon's horn sclerosis; BDI = Beck Depression Inventory; QOLIE = Quality of Life in Epilepsy Inventory; RCI = reliable change index; TLE = temporal lobe epilepsy; VLMT = Verbaler Lern-und Merkfähigkeitstest.

How Different Are the Patients With Bilateral Hippocampal Sclerosis From the Unilateral Ones Clinically?

“…Previous studies also showed similar results in other centers. 11,38,39 Our study similarly showed a good outcome regarding seizure control for the BHS group with 5.50 years (SD 2.92) of follow-up duration after a carefully planned resection.…”

“…5,[8][9][10][11]22 We showed that history of FSE, mental retardation, status epilepticus, psychosis, slowing of the EEG background activity were significant clues for BHS patients in comparison to UHS group.…”

The phenotype of bilateral hippocampal sclerosis and its management in “real life” clinical settings

“…Although the previously published surgical case series have reported good seizure outcomes, unilateral resection in patients with bilateral HS, even if the patient is rendered seizure‐free, can compromise remaining memory function . Moreover, ambulatory electrocorticography recorded from NeuroPace responsive neurostimulation devices has now shown that seizures may arise for several weeks in one hippocampus before then switching to the other .…”

“…Additionally, in this cohort, very few patients ( Although the previously published surgical case series have reported good seizure outcomes, 9,11 unilateral resection in patients with bilateral HS, even if the patient is rendered seizure-free, can compromise remaining memory function. 27,28 Moreover, ambulatory electrocorticography recorded from NeuroPace responsive neurostimulation devices has now shown that seizures may arise for several weeks in one hippocampus before then switching to the other. 29,30 Given that video-telemetry is typically of 1-2 weeks' duration, this may artificially skew interpretation if all, or most, of the seizures during EEG recording happen to arise from one of the sclerosed hippocampi.…”

Comparison of Cognitive Parameters between Bilateral and Unilateral Hippocampal Sclerosis

“…Vogt et al (8) emphasized that despite further deficits in verbal memory, surgically treated BHS patients reported a slightly better subjective outcome than pharmacologically treated BHS patients did. Furthermore, this recent retrospective study carefully assessed neuropsychological outcome after epilepsy surgery in 11 patients with BHS, and reported that verbal memory further declined in 73% of the BHS patients, despite severe impairments already evident at baseline whereas nonverbal memory performance did not change significantly in any patient after surgery (8). We intriguingly showed that UHS and BHS groups did not show any significant difference even before surgery in almost all domains investigating nonverbal memory.…”