To the Editors:
In a case report Luo et al.1 report successful bilateral radiosurgical treatment of a patient with bilateral temporal lobe epilepsy. It would be valuable if these unfortunate patients could be offered a safe and successful treatment without risking further cognitive deterioration. We do have some concerns, however, about this case.
As regards the patient's epilepsy, the aura described is not typical for mesiotemporal seizures, nor are the seizure signs with version of the head and eyes either to the left or to the right. There is scant information on the preoperative neuroimaging and no seizures were recorded during the scalp video–electroencephalography (VEEG). The investigators placed stereo-EEG (SEEG) electrodes bitemporally but recorded only two seizures, one with right and one with left mesiotemporal onset. This work-up has not to an acceptable extent ascertained seizure onset. Recording more seizures might have shown a clear preponderance of seizures from one temporal lobe or a posterior seizure onset with spread to both temporal lobes. Furthermore, we have no information on the patient's behavioral and psychosocial situation before or after this treatment, information which could give an indication about the clinical impact of his memory impairment.
Most importantly, we have serious neuropsychological concerns: We note that the authors assert that this patient had no long-term memory or intelligence deficits following surgery. The patient was functioning close to the floor of the memory test—the Wechsler Memory Scale (WMS)—prior to surgery. The WMS would not be sensitive to postoperative decline in a patient who is already functioning at this low level prior to surgery. This patient's postoperative scores continued to fall very close to the floor of the test (at and around the third centile) in the successive testing sessions. Postoperative neuropsychological outcomes in patients who are functioning close to the floor of standardized neuropsychological tests must be reported using clinically sensitive measures.
Although H.M. is oft cited as a case of pure amnesia, his postoperative memory deficits were complex and he did demonstrate some new learning following surgery.2 Extensive behavioral measures as well as formal neuropsychological test scores have been used to describe and delineate H.M's memory deficits following his surgery. We note that H.M. obtained a higher Wechsler Memory Quotient in 1977 (74) than the patient recorded in this case study. The knowledge about the risks of bilateral temporal lobe resection also includes a number of cases other than H.M.3 We therefore do not feel that this study has demonstrated “no memory deficits” following surgery as claimed. We strongly feel that it would be hazardous to accept the results of this study as a prototype or proof of principle, since bilateral temporal lobectomy carries major risks of severe amnesia.