Cranial CT scan in transient global amnesia

SHORT COMMUNICATION

Acta Neurol Scand., 1986:73:298-301 Key words: Transient global amnesia; transient ischemic attack; cranial CT scan.

Cranial CT scan in transient global amnesia J. Matias-Guiul, R. Colomer2, A. Segural, A. Codinal

Neurology Service 1 and Oncology Service 2, Hospital del Valle de Hebron, UniversidadAutonoma, Barcelona, Spain

ABSTRACT - The occurrence of cerebral infarction in patients with transient global amnesia ( n = 43) was evaluated by CT scan and compared to that of patients with transient ischemic attacks (TIA) ( n = 58) and with no neurological disease ( n = 52). Significant differences were demonstrated between TGA and TIA patients in relation to the control group, but no differences were found between patients with TGA and TIA. Our study suggests a vascular mechanism for TGA and that TGA could be considered a low risk TIA in most cases. Accepted for publication August 15, 1985

Transient global amnesia (TGA) has been defined, since Fisher & Adams ( l ) , as the presence of impairment of short-term memory, incapacity to form new memories, retrograde amnesia and repetitive queries, without other neurological signs and symptoms. TGA episodes have been reported in patients with migraine (2,3), cerebral embolism (1,4-6), intracranial hematomas (7) and neoplasms (8-17), epileptic seizures (18) and other neurological disorders (4,19-22). Occasionally, TGA has been noticed in patients with CT scan images of cerebral infarction (23). When TGA episodes are associated with other neurological deficits (amnestic strokes) they are considered to be of vascular etiology (24). Otherwise, the pathogenesis of TGA is uncertain, although it is mainly postulated as being ischemic or epileptic. One of the reasons adduced against the vascular origin of TGA is that there is rarely a brain CT scan evidence of infarction. Transient ischemic attacks (TIA), however, which are definitely vascular neurological disorders, share the uncommon presence of CT scan lesions (25-30) with TGA. The objective of the present study was to evaluate the presence of cranial CT scan signs of cerebral infarction in TGA patients and to compare this occurrence with that of patients with TIA and patients without neurological disease.

Material and methods The criteria for the diagnosis of TGA were the following: 1) transient amnesic attack with no direct relation to cranial trauma or whiplash, 2) evidence given by a witness of the inability to form new memories, 3) repetitive queries, 4) apparently normal behaviour and orientation, 5 ) evidence given by a witness of normal long-term memory, 6) presence of retrograde amnesia at least during the episode, and 7) absence of other neurological signs and symptoms (31). These criteria, more restrictive than those of other authors (32), rule out other amnestic disorders. Between January, 1983 and December, 1984, 43 Neurology outpatients fulfilled all the diagnostic criteria of TGA. The mean age of the group was 58.4 years. Twenty patients were male and 23 were female. Forty patients had their first episode at the time of the diagnosis, and three patients had had previous attacks. The duration of TGA episodes varied between 15 min and 24 h, and retrograde amnesia lasted for 0 to 15 days. However, in one patient TGA lasted four days and retrograde amnesia persisted for eight days. Hypertension was present in 13 patients, migraine in nine patients and diabetes in four patients. One patient had a previous stroke. There were no cases of amnestic stroke in this series.

CRANIAL CT SCAN IN TGA

Transient ischemic attacks were defined as sudden episodes of focal cerebrovascular failure, with complete resolution of all the symptoms and signs within 24 h (33). The series consisted of 58 patients with a mean age of 54.0 years. There were 45 males and 15 females. Twentysix patients had hypertension and ten had diabetes. Fiftytwo patients with no known neurological disease (NND), who had a CT scan made as part of their routine diagnostic workup, were retrospectively selected from the Neuroradiology archive. CT scans were performed sequentially during a period of four months. Selection and revision of cases was made independently by a member of the neuroradiology staff. Thirty eight patients were male and 14 were female. The primary diagnosis was systemic neoplasm in 29 patients, non-specific headache in 15 patients and postraumatic cephalalgia in eight patients. CT scans were performed, using an EMI-Scanner 1010, one to six weeks after the amnesic episode in TGA patients and between one week and three mmths after the ischemic event in TIA patients.

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(39%) and brain infarction was diagnosed in four patients (9.3%). One of the patients with a CT scan image of an old infarction had had a previous stroke that did not correspond, however, with the ischemic area observed (Tables 1 and 2). We also observed cases of arachnoidal cyst, septum pellucidum and calcifications. One patient, a 50-year-old right-handed man, had CT scan evidence of a right temporal mass. He had progressively worsening headaches and six episodes of TGA in the 15 days prior to his first visit. His neurological examination was normal, except for bilateral papilledema. After being admitted to the hospital and treated with furosemide and dexamethasone, his amnestic episodes subsided. Surgical excision provided the histologic evidence of a multiform glioblastoma (Fig. 1). Twelve (20.6%) patients in the TIA group presented CT scan images of infarction, while no patient in the (NND), group did. The presence of brain infarct in the

Results In the TGA group, CT scan was normal in 22 patients (5l.l0h), cerebral atrophy was present in 17 patients

Table 1 (3scan findings in patients with T G A ( n = 43)

Number of cases (%) Normal Cerebral atrophy Infarction Lipoma Septun pellucidun cist Calcification Intracranial tumor Aracnoidal cist

22 17 4 1 2 2 1 1

(51.1) (39.0) ( 9.3) ( 2.3) ( 4.6) ( 4.6) ( 2.3) I 2.31

Fig. 1. Right temporal glioblastoma with contrast enhancement in a patient with repetitive TGA episodes.

Table 2 Clinical findings of T G A patients with CT scan infarction Case

Sex

Age

Risk factors

Number of episodes

Duration of episode

Permanent retrograde amnesia

CT scan

New infarct of anterior part of corpus callosum. Old right basal ganglia infarct, cerebral atrophy.

findings

14

M

41

-

4

30min

-

16

F

64

hypertension

1

30 min

-

1

15 h

10 h

New left capsular infarct, cerebral atrophy.

1

4days

8 days

Old left capsular infarct, cerebral atrophy.

28

M

64

diabetes stroke hypertension myocardial infarction

37

M

68

-

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J. MATIAS-GUIU ET AL

CT scans of the NND group was significantly different from that of the TIA (x (2) = 12.0; p