Neuroimaging S259

did find sex differences in asymmetry of Broca’s area, but in the opposite direction than initially expected, i.e. larger on the left side in females and more symmetrical in males. We further found a negative correlation between Broca’s area asymmetry and anterior corpus callosum size in women. These findings suggest (1) that Broca’s area may be a specific target of factors determining sex differences: (2) that anatomical asymmetries do not necessarily parallel functional ones and (3) that an inhibitory role of the corpus callosum could account for these complex anatomical-functional relationships.

4-37-04 Functional mapping of paired-word association learning using positron emission tomography: Comparisons of encoding and retrieval capacities

U. Halsband I, B.J. Krause *, D. Schmidt*, L. Tellman *, H. Herzog 2, H.W. Miiller-Gartner *. ’ Departmenf of fsychiatr)! Heinrich-Heine University of Diisseldotf, Germany 2/nsfitute of Medicine, Research Centre JUich, FRG, Germany

This study examined the brain mechanisms engaged during either the encoding or retrieval of paired word associates. Regional cerebral blood (rCBF) flow was measured in thirteen normal subjects with O-ldbutanol positron emission tomography (PET) during encoding and retrieval phases of episodic verbal paired associates. Subjects were visually presented with a list of twelve highly imagenable pairs of two- syllable German words, such as “Kerze” (candle) and “Strasse” (street). Encoding: The subjects were instructed to read the words loudly and to learn the word pair associates (presentation rate: 4 s, interval: 1 s). The same word pair associates were presented in random order 1-3 times until the subjects reached criterion of 80% correct cued retrieval performance as assessed by a prestudy memory test. Retrieval: Only the first member of each pair was used as the cue to retrieval of the second. The subjects read the word aloud and had to recall the associated word from memory. A reference task was employed in which, during scanning, subjects were presented with nonsense words and required to read them aloud. Results indicate that encoding was accompanied by an activation in the left dorsolateral prefrontal cortex and the left anterior cingulum; a bilateral activation was found in the primary visual and visual association areas. In contrast, retrieval was associated with a bilateral activation in the precuneus and prefrontal cortex and in the right cerebellum. Findings point to an anatomical distinction of encoding and retrieval capacities in declarative learning tasks.

4-37-05 Regional cerebral blood flow and periventricular hyperintensity in silent cerebral infarction

Y. Koshi, S. Kitamura, A. Nagazumi, 0. Sakayori, A. Terashi. Second Departmenf of lntemal Medicine, Nippon Medics/ School, Tokyo, Japan

In order to investigate relationship between regional cerebral blood flow (rCBF) and the white matter lesions on MRI in silent cerebral infarction, we quan- titatively measured rCBF using i231-IMP autoradiography method (IMP ARG method) and single photon emission tomography (SPECT) in 38 patients with silent cerebral infarction (SCI group), 22 patients with multi-infarct demen- tia (MID group), and 16 control subjects without pedventricular hyperintensity (PVH) and lacunar infarction on MRI (CL group). Regions of interest (ROls) on rCBF images were set in the frontal(F), temporal(T), parietal(P), occipi- tal(0) cortex, and the cerebral white matter(W). The severity of PVH on MRI T2-weighted image was divided into four grades (grade O-3).

Our results: 1) Though the frequency of hypertension was significantly higher in SCI group and MID group compared with CL group, no significant difference was seen in the mean age among these three groups. 2) rCBF in the white matter and cerebral cortices except the occipital cortex in SCI group was significantly low compared with CL group (rCBFscr/rCBFcL: W 0.87, F 0.87, T 0.87, P 0.88, 0 0.92). 3) rCBF in the white matter and cerebral cortices, especially in the white matter and frontal cortex, in MID group was significantly low compared with SCI group (ICBFM&CBF~L: W 0.69, F 0.71, T 0.74, P 0.75, 0 0.81). 4) the mean grade of PVH in MID group was significantly higher than that in SCI group (SCI 1 .I vs MID 2.5). 5) The severity of PVH was significantly correlated with each rCBF in the white matter and cerebral cortices, especially in the white matter and frontal cortex.

Our findings suggest that the quantitative measurement of rCBF by IMP ARG method is useful for the follow-up study in the patients with silent cerebral infarction as well as the evaluation of the severity of PVH on MRI.

4-37-06 Brain perfusion defects in early and remote period after crania-cerebral trauma assessed using brain SPECT and aminophylline test

P. Lyczak. P. Lass, M. Sygitowicz, E. Stgpien-KoCmiel. Naval Hospital and Medical UniversiM Gdafisk, Poland

Cerebral perfusion alterations immediately after head trauma are fairly well

described, but we know little about the remote effects of trauma, together with cerebrovascular reactivity. The aim of the study was to assess regional brain perfusion in different periods after trauma together with reversibility of changes after aminophylline.

We perfoned brain SPECT studies with a triple-head Multispect-3 (Siemens) rotating gammacamera in 72 patients, 42 men, 30 women, age: lQ-64 yrs, between the first day to 12 years after CloSSd crania-cerebral trauma. The study was repeated 2 days later, after i.v. injection of 0.25 of aminophylline, an agent causing an inversed-steal phenomenon. In 14 patients the repetitive scanning after 1 .O g hypercapnia-causing agent, acetazolamide, i.v., was performed. The comparative data-base were 16 healthy volunteers.

Results: we found cerebral perfusion assymetries in 89/72 patients; all in the 20 patients in the early stage after the trauma, in 49/52 patients in a remote period after trauma. Simultaneous CT scanning revealed focal abnormalities only in 21 patients. Asymmetry index (Al) in hypoperfused areas varied be- tween 7-22%, mean 12.8 f 2.9%. Bifocal asymmetries on the axis: coup - contre coup was seen in 62.5% of patients, multiple asymmetries in 20.8%. Bilateral hypofrontalism - decreased frontal lobes perfusion was seen in 75% of early stage patients and 58% of remote stage patients. The aminophylline test increased HMPAO accumulation in hypoperfused areas in 41% of pa- tients, mean by 6.3 f 2.8%, no change was seen in 59.4. Acetazolamide test increased asymmetry indices in all patients.

Comments: the authors conclude the long-lasting alterations of cerebral perfusion after cerebral trauma. Cerebral blood flow changes may be focal, or bifocal, but the involvement of frontal lobes, independent of trauma site, is also frequently seen. We postulate the usefulness of aminophylline test in the assessment of perfusion reserve in post-traumatic period and usefulness of brain SPECT scanning in the clinical and medico-legal assessment.

4-37-07 Corpus callosum. A morphometric analysis E. Manaut-Gil. Neurobgy Section, Nuestra Sefiora de/ Pino Hospital, Las Palmas, Gran Canada, Spain

Objectives: (1) Assessment of the normal morphometric characteristics of the corpus callosum (CC) (2) Including or excluding the differences between men and women. (3) Analysis of the postnatal ontogenical development patterns and ages fo initiation and profile (s) of possible morphometric involutions. (4) Derived from the above, and based on the volumetric values, inference of the translators of hemispherical cortical evolutive and involutive behavior, lobar as regional.

Material and Method: In 910 patients correlative with diverses neurological clinical entities, all with cerebral MRI, there are 514 cases (260 men, 254 women), ranging between 1 month and 89 years of age, all with normal MRI, and presenting in the saggital interhemispherical median plane, with well defined image of the CC. The CC was measured in 8 regions: the cerebral hemispheres (CH) in 4 parameters.

Results and Conclusiones: (1) It is surprising to find the very wide mor- phological variety of the CC. (2) The CH and CC are larger in men as compared to women. (3) The ontogenical evolution of the CC seems to be in “steps”. (4) The volumetric growth of the anterior region of CC is initiated sooner in women than in men. (5) The greatest axonic population, is in the anterior segment of the CC and followed, in decreased order, by the middle and isthmic regions.

4-37-08 Kearns-Sayre Syndrome: Genetic correlations with muscle pathology and MRI findings

S.K.N. Marie, U.C. Reed, V. Palou, M.S. Carvalho, A.A.S. Carvalho. Departamento de Neurobgia, Faculdade de Medicina USf? S&o Paula, Srasil

Studies were carded out of six patients with Kearns-Sayre Syndrome (KSS). All were examined for presence of deletion/insertion in the mitochondrial DNA. Findings were analyzed of supplementary exams, muscular biopsy, and neu- roimage in the light of results of research on mutation of the mitochondrial DNA. All of them presented deletion of the mitochondrial DNA, by the Southern blot method. One case of KSS presented insertion of 4.9 kb. SDH was the most sensitive histochemical staining in demonstrating mitochondrial proliferation upon muscle biopsy. There was no correlation between the size of deletion and the intensity of the muscular morphological alterations and the severity of the clinical picture.

The lesions detected by head magnetic resonance in 5 of them were extremely stereotyped with distribution in bulbar, pontine, and mesencephalic tegmentum, with compromise of the main viae of internuclear connection, of the structures of supranuclear regulation of the vertical conjugated movement and descending viae for control of the conjugated gaze, horizontal and vertical, and with compromise of the nuclei of the Ill, IV, and VI cranial pairs. With this distribution, it can be said that alterations of the brain stem play a part in the genesis of ophthalmoplegia externa.