Epilepsia, 35(6): 1321-1327, 1994 Raven Press, Ltd., New York 0 International League Against Epilepsy Brief Communication Reversible Amnesia Associated with a Left Temporal Hematoma in a Case of Right Temporal Complex Partial Seizures Deborah T. Combs Cantrell, *Harvey S. Levin, ?Daniel X. Capruso, and $Howard M. Eisenberg Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas; *Division of Neurosurgery, University of Texas Medical Branch, Galveston, Texas; ?Department of Neurology, Buffalo General Hospital, Buffalo, New York; and #Division of Neurological Surgery, University of Maryland Medical System, Baltimore, Maryland, U . S . A . Summary: We report the case of a 44-year-old woman with complex partial seizures (CPS) of right frontotemporal origin who developed generalized amnesia after undergoing intracranial electrode implantation complicated by left hippocampal hemorrhage. Serial memory testing disclosed recovery from the amnesic disorder, while repeated magnetic resonance imaging (MRI) showed reso- lution of her left hippocampal hemorrhage in a 2-month period. A second intracarotid amytal procedure confirmed the capability of her left temporal region to support memory. Consequently, a right orbitofrontotemporal lobectomy was performed without complication. Key Words: Amnesia-Complex partial seizures-Hematoma-Intracarotid amytal procedure. Unilateral temporal lobectomy is considered not to produce a generalized memory disorder in which the patient is “unable to record the daily current of conscious experience” (Penfield and Milner, 1958) provided that the contralateral hippocampus is intact. However, Penfield and Milner (1958) reported two patients who developed a persistent, generalized memory disorder after partial left temporal lobectomy that included uncus and hippocampus. The unsuspected abnormality postulated by Penfield and Milner (1958) in the contralateral temporal lobe was confirmed by neuropathologic findings when 1 of the patients died 13 years after operation. A necropsy report (Penfield and Mathieson, 1974) documented right hippocampal atrophy and diffuse gliosis of right temporal white matter that was ascribed to incisural sclerosis at time of birth. More recently, Warrington and Duchen (1992) reported a case of global amnesia after right temporal lobectomy in which a sclerotic lesion of the unoperated left hippocampal formation was noted at autopsy. To evaluate risk of generalized amnesia after unilateral temporal lobectomy, Milner et al. (1962) incorporated memory testing as part of the intracarotid amobarbital procedure (IAP). By pharmacologically inactivating the hippocampus ipsilateral to the suspected seizure focus, the capability of the contralateral hippocampus for supporting memory could be tested. We have studied a patient with simple and complex partial seizures (SPS, CPS) of right temporal origin who became amnesic when she sustained a left mesiotemporal hematoma during stereotaxic placement of bilateral depth electrodes. CASE REPORT History A 44-year-old right-handed woman with medically intractable SPS and CPS with onset at age 14 years without identifiable risk factors continued to have three to four CPS monthly and was evaluated for surgical intervention. At the initial assessment, the patient was treated with Depakote 1,000 mg, which was replaced in July 1992 by dilantin 250 mg. Neurologic examination was normal. Magnetic resonance imaging (MRI) scan was normal. Extracra- Received July 1993; revision accepted September 1993. Address correspondence and reprint requests to Dr. D. T. Combs Cantrell at Epilepsy Monitoring Unit, Department of Neurology, UT Southwestern Medical Center, 5325 Harry Hines Blvd., Dallas, TX 75235-9036, U.S.A. 1321 1322 D . T. COMBS CANTRELL ET AL. nial EEG studies, including scalp and sphenoidal electrodes, showed independent interictal discharges over the right temporal and bifrontal regions. Focal slowing was noted over the same areas. Ictal extracranial recordings showed seizure onset over the right temporal and bitemporal regions. A cerebral arteriogram was normal. Preoperative neurophysiological findings Initial neuropsychological assessment was performed on February 12, 1992, as part of the phase I evaluation. The patient was fully cooperative with all procedures despite complaints of depressed mood, diminished energy, and mental slowing. She was receiving Depakote 1,000 mg three times daily (t.i.d.) at the time of testing. Intellectual ability, problem solving, and attention As summarized in Table 1 , scores on the Wechsler Adult Intelligence Scale-Revised (WAISR) (Wechsler, 1981) were generally in the low average to average range, with disproportionately poor performance on measures (Digit Span, Arithmetic) known to. be sensitive to attention and concentration disturbances. On the Wisconsin Card Sorting Test (Berg, 1948), the patient attained five of six categories and had a perseverative error rate of 15%, indicating a normal level of flexibility in problem solving. Language and visuospatial function Consistent with the patient's fluent nonaphasic conversational speech, naming to confrontation and verbal fluency (Benton and Hamsher, 1978) were within normal limits. Dichotic listening (Halwes, 1991) disclosed a mild right ear advantage consistent with left hemisphere specialization for language (Table 1). Visuospatial and visuoperceptive scores were variable and characterized by impoverished invention of unique, abstract designs (JonesGotman and Milner, 1977), difficulty in discriminating photographs of unfamiliar faces (Benton and Van Allen, 1968), and poor copying of a complex geometric figure (Rey, 1964). Memory and orientation The patient was fully oriented to time, place, and person. Although consistent recall (Buschke and Fuld, 1974) of a 12-word list across trials was in the low-normal range, cued recall (initial letter was cue) and recognition (four choices) were normal and the patient recalled nine words after a 30-min delay TABLE 1. Summary of neuropsychologiculjindings" ~~ Two months postimplantation 8118/92 Preoperative 211 21v2 Test Memory Selective Reminding Test Recall LTS CLTR Cued Recall 30-min delay multiple choice Rey-Osterreith Complex Figure COPY Immediate 30-min delay Kimura Recurring Figures Recognition (net) Geometric Nonsense Total Wechsler Memory Scales Logical Memory I Logical Memory 11 Visual Representation I Visual Representation 11 Verbal fluency Total no. of words Design fluency Total no. of designs Dichotic listening Asymmetry score Raw score Raw score 42172 24/72 14/72 911 1 12/12 9/12 50th 8th 47172 37172 22/72 911 1 12112 6/12 26.5136 12.5136 12.5136 4th 4 t h 6th 33/36 8136 8/36 6 of the 12 words after a 30-min Epilrpsia, Vol. 35, N o . 6, 1994 delay on any assessment after electrode placement (Fig. I). Immediate and delayed prose recall (Logical Memory) at 2 months after electrode placement decreased from average level to the low-normal range (Table 1). In comparison with the patient’s preoperative reproduction of the Rey Figure, her scores at 2 months after electrode placement reflected marked memory deficit despite improved copying when the design was in view. Nonverbal recognition memory also remained impaired (Table 1). Medication at the time of hospital discharge was dilantin, 250 mg orally (P.o.), at bedtime. Repeat IAP and right temporal lobectomy Because of the resolving left hippocampal hemorrhage and associated amnesia, we were concerned about proceeding with right temporal lobectomy. Was the capability of the patient’s left temporal lobe for supporting memory compromised to the point of risking permanent amnesia by removing her right hippocampus? To evaluate the residual memory capabilities of the patient’s left hippocampus, we confined repeat IAP on October 13, 1992, to a right hemisphere injection. The testing procedure and memory objects were identical to the right hemisphere IAP performed on May 5, 1992. Comparison of the results obtained for the initial and follow-up intracarotid amytal injections of her right hemisphere (Table 2) showed a fairly stable level of anterograde and remote memory with no evidence of a substantial decrease in performance after the left hippocampal hemorrhage. In view of the preserved capability of the patient’s left temporal region for supporting memory, we performed right REVERSIBLE AMNESIA 1325 FIG. 2. A: Axial magnetic resonance imaging (MRI) 1 day after depth electrode implantation with a 1.5-T imager shows intracerebral hematoma measuring <2 cm in diameter in left hippocampus along the left temporal electrode. A repeat MRI scan 6 days (B) after electrode placement disclosed partial resolution of the left hippocampal lesion and a small area of increased signal in the subcortical region of left frontal lobe. MRI 3 weeks (C) and 3 months (D) after electrode placement showed resolution of the areas of increased intensity. 2C,D orbitofrontotemporal lobectomy, including the hippocampus, on October 16, 1992 without complications. Neuropsychological findings after right temporal lobectomy Examination 2 months after a right temporal lobectomy showed the patient to be alert, fully oriented, and highly cooperative with all procedures; she reported that she had been seizure-free. As shown in Fig. 1, recall of a word list across trials and delayed recall was decreased slightly from the initial level. Prose recall (WMS-R Logical Memory) closely approximated the low-normal level she had obtained before temporal lobe excision, but was poorer than the initial score. In comparison with prelobectomy scores on the Recurring Figures Test, recognition memory for geometric designs im- proved despite a decrease in recognition of nonsense designs. Copying the Rey-Osterreith Complex Figure was poor relative to the patient’s preoperative performance, precluding unambiguous comparison of delayed recall. Although the patient’s short-term recall of the geometric designs on the WMS-R decreased from the 54th percentile on preoperative testing to the 19th percentile at follow-up, delayed recall of the same material improved (Table 1). Memory after right temporal lobectomy was characterized by a decrement in retention of nonverbal material and an inconsistent pattern of changes in verbal recall. Productivity on measures of verbal and figural fluency was unimpaired and showed marked improvement to average level in generation of novel, abstract designs. Dichotic listening showed greater asymmetry in auditory processing of verbal mateEpilepsia, Vol. 35,N o , 6, 1994 D. T. COMBS CANTRELL ET AL. 1326 rial. The magnitude of the patient’s right ear advantage had increased significantly at follow-up examination (Table 1). DISCUSSION The salient findings in our patient included (a) right hippocampal dysfunction documented by initial IAP, (b) an amnesic syndrome associated with a left hippocampal hematoma that arose as a complication of implantation of intracranial electrodes, (c) reversal of her generalized amnesia paralleled by resolution of the left hippocampal hematoma, (d) repeat IAP indicating that the patient’s left temporal region could support memory when right temporal lobe was pharmacologically inactivated; and (e) a postlobectomy clinical course characterized by a mild decrement in memory for nonverbal material, with no consistent affect on verbal retention and no evidence of a generalized amnesic disorder. We attribute our patient’s reversible amnesia to her transient bilateral hippocampal dysfunction when the left hippocampal hematoma was superimposed on her preexisting right temporal pathology. Resolution of the left hippocampal hemorrhage was documented by serial MRI scans and was paralleled by clearing of her disorientation, shrinking retrograde amnesia, and overall improvement in tests of memory for new verbal and nonverbal information. Our patient’s amnesia parallels the cases at the Montreal Neurologic Institute of persistent amnesia (Penfield and Mathieson, 1974) after unilateral hippocampal excision in the presence of occult pathology of the contralateral hippocampus documented at necropsy. Our findings are also relevant to the assumption that memory testing during IAP can evaluate the risk of persistent amnesia after unilateral hippocampal removal (Loring et al., 1992). Injecting the left internal carotid artery (and presumably inactivating the left temporal region) during the initial IAP produced marked impairment of memory for new information, a finding interpreted as evidence of right hippocampal dysfunction. In contrast, the patient’s memory was not perturbed by pharmacological inactivation of her right hippocampus. The marked ipsilateral-contralateral asymmetry in mnemonic efficiency displayed by our patient is typical of patients with right temporal lobe foci, whereas patients with CPS of left temporal origin tend to exhibit more symmetrical memory scores after injection of the hemisphere ipsilateral to the focus rather than the contralateral hemisphere (Rausch et al., 1989). According to conventional inEpilepsia, Vol. 35, No. 6 , 1994 terpretation of the IAP, our patient’s findings implied that a left hippocampal insult would place her at risk of developing a generalized amnesia. Consistent with this interpretation, she became globally amnesic after sustaining a left hippocampal hematoma. Consequently, serial memory testing and a second IAP were performed to evaluate the risk of producing persistent amnesia after right temporal lobectomy. 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