The anatomy and the MRI anatomy of the interhemispheric cerebral commissures

Correlation of myelin-stained or cryotomic sections of human brain with inversion-recovery MR images can display the cerebral commissures as white-matter tracts (in hypersignal on MRI), crossing the mid-line. MRI shows routinely in three orthogonal planes a) the corpus callosum stretched above the supra-tentorial ventricles, it's four portions (rostrum, genu, body and splenium) and connections with the Deep Grey Nuclei b) the fornix, intralimbic commissure joining anteriorly the mammillary bodies (through it's columns) to the alveus posteriorly and inferiorly (via it's two crura), arcing around the thalamus and lying over the hippocampus and the dentate gyrus as shown on the frontal sections c) the anterior commissure, white-matter tract connecting the two temporal lobes. In axial view, the anterior commissure has the shape of bicycle handlebars, coursing posteriorly, inferiorly and laterally behind the head of the caudate nucleus and passes into the lateral nucleus of the globus pallidus into the inferior and middle temporal gyri. Because the anterior commissure is easily recognisable in all planes, it's appears to be a important landmark for identification of the lateral and medial nuclei of the globus pallidus on axial and sagittal planes d) at least, the posterior commissure, anterior margin of the pineal region, closely related to the superior colliculi, acquire a major importance in the AC-PC line delineation becoming a reference landmark for stereotatical procedures.     

Spinal pathology in spinal muscular atrophy in comparison with amyotrophic lateral sclerosis

We analyze neuronal cytopathology and secondary reactions in spinal-muscular atrophy (SMA) in comparison with amyotrophic lateral sclerosis (ALS). In a series of SMA and ALS cases, immunohistochemistry was performed on spinal cord sections for neuronal, astroglial and microglial antigens, ubiquitin and tau proteins. Swollen motoneurons staining for phosphorylated neurofilament proteins are seen in most SMA but few ALS cases. Ubiquitinated inclusions are found only in ALS. In SMA, glial bundles are prominent in anterior roots, to lesser extent in posterior roots. In ALS, glial bundles are seen only in some cases. While basic histopathologies are similar in both types of motor neurone diseases, neuronal cytoskeletal pathology is more prominent in SMA, possibly reflecting a more acute degenerative process. The presence of axon spheroids and glial bundles also in posterior horns/roots of both types of motor neurone disease suggests spread of degenerative pathology beyond the motor system.     

The normal anterior commissure of the glottis

OBJECTIVE: We characterized the normal width of the anterior commissure of the glottis by measuring its dimensions on CT scans obtained in patients who had no laryngeal disorders. SUBJECTS AND METHODS: CT scans of patients referred for cervical CT myelography were prospectively reviewed by a single board-certified radiologist. Axial images through the anterior commissure (localized by vocal process of the arytenoid cartilage, the vocal muscle, or both) were magnified on the viewing console of the CT scanner. Window and level were chosen to simulate our routine settings for CT scans of the neck. Anteroposterior width of the anterior commissure was measured using an electronic ruler with 1-mm marks. RESULTS: Sixty-five patients were prospectively evaluated. Nine patients were excluded because of substantial motion artifact, and another 18 were excluded because CT images did not include the entire larynx. Thus, the final study group included 38 patients. The average width of the anterior commissure was 1.02 +/- 0.56 mm. The width was less than or equal to 1.1 mm in 22 (58%) of 38 patients. The width was less than or equal to 1.7 mm in 35 (92%) of 38 patients. Forty-two percent (16 of 38 patients) had anterior commissures wider than 1.0 mm. The maximum width of 2.2 mm was seen in only one patient. CONCLUSION: The mean width of the anterior commissure was approximately 1.0 mm. However, 42% of patients had anterior commissures wider than 1.0 mm. In our series, using an upper limit of 1.6 mm as a normal measurement for the anterior commissure would have included 92% of patients, and an upper limit of 2.1 mm would have encompassed the mean plus two SDs.     

Oculomotor nuclear pathology in amyotrophic lateral sclerosis

We examined the oculomotor and/or trochlear nuclei of 27 amyotrophic lateral sclerosis (ALS) patients and 10 controls by histological and immunohistological methods. Their neurons were relatively well preserved. In 7 of 22 sporadic ALS patients (including 3/3 ALS with ophthalmoplegia) and in 4 of 5 ALS patients with dementia, some morphological changes similar to those in anterior horns (Bunina bodies, ubiquitin-positive skein-like inclusions, Lewy body-like inclusions, conglomerate inclusions and spheroids) were rarely, but clearly seen. These changes were not observed in controls. Our results suggest that the oculomotor and trochlear nuclei in ALS patients are slightly affected in a manner similar to that in the anterior horns, but the degree is less than that necessary for development of ophthalmoplegia in the majority of ALS patients.     

Three-dimensional analysis of the vascular system in the rat spinal cord with scanning electron microscopy of vascular corrosion casts. Part 1: Normal spinal cord

Vascular corrosion casts of polyester resin in the normal spinal cord at C4-C6 and C7-T1 were inspected three-dimensionally by scanning electron microscopy in 13 rats. Arteries and veins were easily differentiated by the impression pattern of endothelial nuclei on the casts. The centrifugal arterial system from the sulcal arteries supplied most of the gray and white matter in the ventral and lateral spinal cord. Each sulcal artery supplied only one side of the cord. The average number of sulcal arteries was 2.6 per mm. The centripetal arterial system from the posterior spinal arteries fed the posterior gray and white matter. In contrast with classical concepts, there was no pial arterial plexus on the ventral and ventrolateral surface except for infrequent transverse branches from the anterior spinal artery. In the posterior columns, two types of large veins were identified: the posterior medial septal veins and the posterior oblique veins that drained the posterior columns, medial posterior gray matter, and posterior gray commissure. The remainder of the gray and white matter was drained by the sulcal veins and the radial veins. This method clearly demonstrates the three-dimensional structure of both the arterial and venous system in the rat spinal cord.     

Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion

The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/substantia nigra and central gray. For instance, only the medial septal nucleus projected substantially to the thalamus whereas the anterior septum was the only nucleus projecting to the caudal midbrain including the central gray. The anterior and lateral septal nuclei also differ in the way in which their projection to the preoptic hypothalamus terminated. The midline septal division is composed of the dorsal septal nucleus, nucleus septalis impar and nucleus of the posterior pallial commissure. The latter two nuclei projected to the lateral habenula and, at least the nucleus of the posterior pallial commissure, to the mammillary complex. The dorsal septal nucleus projected to the preoptic and periventricular hypothalamus and the anterior thalamus, but its central part seemed to project to the caudal midbrain (up to the midbrain central gray). Finally, the ventromedial septal division (ventromedial septal nucleus) showed a massive projection to the anterior and the lateral tuberomammillary hypothalamus. Data on the connections of the septum of P. hispanica and Gecko gekko are discussed from a comparative point of view and used for better understanding of the functional anatomy of the tetrapodian septum.     

Some issues regarding the use of electroencephalography and brain evoked potentials in occupational medicine

Acute experiments were performed on cats with intracellular recording of efferent and unidentified neurons of the anterior suprasylvian and posterior lateral gyri of the parietal cortex, to study the antidromal and synaptic responses to stimulation of the lateral and medial groups of intrinsic nuclei of the pons. Oligo- and polysynaptic components were detected, along with complex EPSP due to convergence of axons from fast- and slow-conducting neurons. Antidromal and synaptic responses were demonstrated in the same parietal cortex neurons, demonstrating a double connection between the intrinsic nuclei of the pons and the associated parietal cortex. The possible pathways of these connections are discussed, along with their features and importance in the functioning of pontocortical connections.     

Use of the thoracic aorta for renal revascularization

OBJECTIVE: The primary role of the anterior cruciate ligament is to resist anterior subluxation of the tibia. When the ligament is torn, the tibia is free to sublux anteriorly when the leg is pulled forward. In addition to visualizing the anterior cruciate ligament directly, MR imaging can show joint alignment. The purpose of this study was to test the efficacy of MR images of anterior subluxation of the tibia for diagnosing complete tears of the anterior cruciate ligament. MATERIALS AND METHODS: We evaluated the records of 120 consecutive patients who underwent MR imaging of the knee and subsequently had arthroscopy. Arthroscopy showed a complete tear of the anterior cruciate ligament in 21 patients, a partial tear in eight patients, and an intact anterior cruciate ligament in 91 patients. Two radiologists together reviewed the MR images, and interpretation of anterior cruciate ligament integrity was reached by consensus. The anterior cruciate ligament was categorized as intact, completely torn, or partially torn on the basis of conventional MR imaging criteria. The degree of anterior subluxation of the tibia was measured on a separate occasion in random order by a radiologist who used a sagittal section through the middle of the lateral femoral condyle. On the selected image, two vertical lines parallel to the left and right margins of the image frame were drawn tangent to the posterior cortical margins of the lateral femoral and tibial condyles. Anterior subluxation of the tibia was determined by the distance in millimeters between these two lines and measured with calipers by using the 5-cm scale on the images. Measurements were considered reliable only to one half of the smallest increment of this scale (i.e., 5 mm). Accordingly, tibial subluxation (x) was measured in 5-mm increments, with x < or = 0 mm designated grade 0, 0 mm < x < or = 5 mm designated grade 1, 5 mm < x < or = 10 mm designated grade 2, and so forth. RESULTS: Conventional MR imaging criteria had 90% sensitivity and 94% specificity for diagnosing complete tears of the anterior cruciate ligament. According to the receiver-operating-characteristic (ROC) curve, anterior subluxation of the tibia greater than 5 mm (grade 2 or greater) was considered to be the optimal threshold (sensitivity, 86%; specificity, 99%) for diagnosing complete tears of the anterior cruciate ligament. Notably, none of the six false-positive diagnoses of complete tears by conventional criteria (three partial tears and three intact ligaments at arthroscopy) were misdiagnosed when tibial subluxation was used as the diagnostic criterion. Subluxation greater than 5 mm can be falsely negative with chronic tears of the anterior cruciate ligament (n = 2) or when a displaced bucket-handle tear of the lateral meniscus blocks anterior subluxation of the tibia (n = 1). CONCLUSION: An anterior tibial subluxation greater than 5 mm (grade 2 or greater) is a simple objective measurement that serves as a helpful adjunctive sign in the diagnosis of complete tears of the anterior cruciate ligament. This sign also offers improved discrimination of complete from partial tears of the anterior cruciate ligament.     

Effects of knife-cut lesions of the medial forebrain bundle in self-stimulating rats.

Unilateral frontal-plane knife-cut lesions were made in the anterior medial forebrain bundle ipsilateral to a lateral hypothalamic self-stimulation electrode. Behavioral effects of the knife cut on self-stimulation reward and operant performance capacity were measured via the reward summation function method. Knife cuts placed at the level of the anterior commissure were ineffective in altering reward or motor/performance capacity, whereas knife cuts just posterior in the caudal lateral preoptic area degraded reward and sometimes impaired motor/performance capacity. In a second experiment, knife cuts placed posterior to the ventral tegmental area were ineffective unless they intruded on the ventral tegmental area itself. Several small knife cuts placed just anterior to the ventral tegmental were effective in reducing self-stimulation reward. The results are discussed in terms of the anatomical substrate of lateral hypothalamic self-stimulation reward and as a first step in a larger mapping study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual learning suppressed by cooling the temporal pole.

Three female Macaca fasicularis were trained to remember colored photographs of objects over delays of 0, 15, 30, and 45 sec. Then 2 pairs of cooling devices were implanted bilaterally over the anterior 9 mm of the temporal lobe. One pair (anterior pair) covered the medial part of the temporal tip (area TG), starting at the rhinal sulcus and extending 3 mm laterally. The 2nd pair (posterior pair) was placed 3 mm lateral to the anterior pair, covering the rest of TG and the anterior extreme of the inferotemporal gyri, anterior TE. Cooling either pair of probes produced a deficit at all delays, but the deficit was greater at the longest delays. Cooling the anterior pair greatly increased the disruption of recall produced by an interfering stimulus. When all 4 probes were cooled, which suppressed the function of the entire temporal tip, performance dropped to chance at all delays. Under this condition, Ss could not learn new visual discriminations but could perform previously learned visual discriminations. Results are consistent with the suggestion that the temporal pole is the store for the brief anterograde memory that is available to the medial temporal amnesics. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delayed-nonmatching-to-sample performance is impaired by extensive, but not by limited, lesions of the thalamus in the rat.

Two experiments were conducted to determine whether lesions affecting limited areas of the thalamus can impair the performance of rats on a spatial delayed-nonmatching-to-sample (DNMTS) task trained before surgery. In Exp 1, DNMTS was not affected by lesions produced by injecting 5 μl of 1 mM N-methyl-D-aspartate (NMDA) into either the midline thalamus (n?=?16) or bilaterally 1.0 mm from the midline (n?=?16). In Exp 2, radio-frequency lesions were made 1.0 mm lateral from the midline at 3 anterior–posterior locations that destroyed the full rostral–caudal extent of the lateral internal medullary lamina (L-IML; n?=?8), or at single anterior–posterior locations that destroyed either the anterior (n?=?8) or posterior (n?=?8) portions of the L-IML site. Although complete L-IML lesions disrupted DNMTS performance to an extent comparable to that of another study (R. G. Mair and D. M. Lacourse; see record 1992-42024-001), lesions that were restricted to either the anterior or posterior portion of the L-IML site had no significant effect on this task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maternal smoking during pregnancy, growth, and bone mass in prepubertal children

OBJECTIVES: A long-term follow-up study with nuclear magnetic resonance (NMR) imaging was undertaken to detect the morphological onset and to establish the early diagnosis in apical hypertrophic cardiomyopathy (HCM). BACKGROUND: A spadelike configuration on left ventriculogram (LVG) is regarded as a diagnostic criterion for the classical apical HCM. There also exists a segmented hypertrophy at the apical level without indicating the spadelike features (a nonspade configuration). To detect the hypertrophied myocardium of the nonspade configuration, circumferential scrutiny of the apex is required. Although both configurations can be underlying causes of giant negative T waves, etiological relationship between the two is not clarified. METHODS: The criteria for the spadelike configuration defined on left ventricular short-axis NMR images were as follows: (apical maximal thickness > or = 15 mm), (apical anterior thickness over basal anterior thickness > or = 1.3) and (apical posterior thickness over basal posterior thickness > or =1.3). Thirteen patients who had predominant hypertrophy (> or = 15 mm) at the apical level without the spadelike configuration underwent NMR imaging twice before and after 54+/-10 months' follow-up. RESULTS: Apical hypertrophy that had been confined to the lateral wall in four, the anterior-lateral wall in two, and the septal-anterior wall in one developed to become circumferential hypertrophy that fulfilled the criteria for the spadelike configuration after the follow-up period. CONCLUSIONS: The spadelike configuration can begin with the nonspade configuration and therefore, both can constitute a single disease entity of apical HCM. The early diagnosis of apical HCM can be achieved by identifying the hypertrophy frequently confined to the lateral wall at the apical level.     

Diversity of connections of the temporal neocortex with amygdaloid nuclei in the dog (Canis familiaris)

Reciprocal connections of amygdaloid nuclei with the temporal neocortex in the dog were investigated. Injections of fluorescent tracers and BDA into particular temporal areas were made in eleven dogs. The topographical arrangement of connections and variations in their density differentiate the temporal neocortex in the dog into a few regions. Among them, the cortex involving the anterior part of the ectosylvian gyrus did not send any amygdalopetal projection. The middle ectosylvian, dorsal zone of the posterior ectosylvian and the anterior part of the Sylvian gyrus were weakly connected with the amygdala. The cortical region involving the ventral zone of the posterior ectosylvian and composite posterior areas, as well as posterior Sylvian gyrus, was characterized by profuse connections with the amygdaloid complex. Cortico-amygdaloid connections originate in the wide cortical area of the auditory cortex of the middle and dorsal part of the posterior ectosylvian gyrus as well as in the auditory association cortex located in the ventral ectosylvian, composite posterior and posterior Sylvian gyri. The connections showed a dorso-ventral gradient of increasing density, in the direction of association fields. The most substantial projection taking rise from the ectosylvian posterior and posterior composite gyri terminated preferentially in the pericapsular sector of the lateral amygdaloid nucleus and, to a lesser degree, in its medial sector. Terminals of connections originating in the Sylvian gyrus occupied preferentially the intermediate part of the lateral nucleus, slightly more medially than that from the ectosylvian and posterior composite areas. Additionally, axonal terminals derived from the composite posterior and Sylvian posterior areas were observed in the basal parvocellular and magnocellular nuclei. Neocortical projections were reciprocated by amygdalofugal connections with two exceptions: the basal magnocellular nucleus was distinguished by a substantial amygdalofugal projection to the temporal neocortex focused on the dorsal Sylvian gyrus, and the central nucleus of the amygdala, in contrast, received an exclusively corticofugal projection.     

Dynamics of obstruction in acontractile bladder: attempt at management

Five patients with acontractile bladders were observed during lateral voiding cystourethrography in the resting and straining states. Two abnormalities were noted: (1) posterior displacement of the bladder with closure of the posterior vesicourethral angle on straining, and (2) plication of the bladder over the symphysis pubis, resulting in the formation of an anterior pseudodiverticulum. Two other abnormalities are discussed: closure of the anterior vesicourethral angle, and descent of the bladder and prostate in flaccid paraplegia, causing plication at the prostatic apex. Surgical techniques for the correction of the abnormalities are described.     

Ventricular enlargement in poor-outcome schizophrenia

BACKGROUND: A subset of patients with schizophrenia, defined on the basis of longitudinal deficits in self-care, may show a classic ("Kraepelinian") degenerative course. An independent validator of the phenomenologically defined Kraepelinian subtype might be provided by a structural indicator of possible brain degeneration: ventricular size as measured by computed tomography (CT). METHODS: To examine whether Kraepelinian patients would show a differential increase in ventricular size over time, two CT scans were conducted at intervals separated by > 4 years, an average of 5 years. Fifty-three male patients with DSM-III-R diagnoses of chronic schizophrenia were subdivided into Kraepelinian (n = 22; mean age = 42 +/- 6 years) and non-Kraepelinian (n = 31; mean age = 38 +/- 12.2 years) subgroups. Kraepelinian patients were defined on the basis of longitudinal criteria: > 5 years of complete dependence on others for life necessities and care, lack of employment, and sustained symptomatology. Thirteen normal elderly volunteers (mean age = 60 +/- 17.8) were also scanned at 4-year intervals. CT measurements were made by raters without knowledge of subgroup membership. A semiautomated computer program was used to trace the anterior horn, lateral ventricles, and temporal horns for each slice level on which they were clearly seen. RESULTS: The ventricles showed a bilateral increase in size over the 4-year interval in the Kraepelinian subgroup, more marked in the left hemisphere than the right. By contrast, neither the non-Kraepelinian subgroup nor the normal volunteers showed significant CT changes from scan 1 to scan 2. CONCLUSIONS: Thus, the longitudinal dysfunctions in self-care that characterize the Kraepelinian patients were associated with an independent indicator of brain abnormality.     

Meniscal position on routine MR imaging of the knee

OBJECTIVE: To determine the prevalence of meniscal protrusion (i.e. location of the outer edge of a meniscus beyond the tibial articular surface), and to determine its relationship with internal derangement, joint effusion, and degenerative arthropathy. DESIGN AND PATIENTS: Sagittal and coronal MR images of 111 abnormal and 46 normal knees were evaluated for the presence of meniscal protrusion. We set 25% as the minimum amount of displacement considered abnormal because this was the smallest amount of displacement we could confidently discern. Presence of meniscal tear, anterior cruciate ligament (ACL) injury, joint effusion, or osteophytosis was also recorded. RESULTS AND CONCLUSION: Normal examinations demonstrated protrusion of the medial meniscus in 6.5% of sagittal images and 15% of coronal images, and of the lateral meniscus in 2% and 13%, respectively. Fisher's exact test demonstrated a statistically significant difference between the normal and abnormal groups for the medial meniscus on both sagittal (P < 0.0001) and coronal (P = 0.01) images, but not for the lateral meniscus in either plane (P > 0.2). A protruding medial meniscus was associated with effusion and osteophytosis (P < 0.05) but not with meniscal or ACL tear (P > 0.1). Posterior protrusion of the lateral meniscus was only associated with ACL injury (P < 0.0001); protruding anterior horns and bodies of lateral menisci were not associated with any of the four abnormalities. It is concluded that the medial meniscus may occasionally protrude more than 25% of its width, but protrusion is more often due to effusion and osteophytes. Protrusion of the posterior horn of the lateral meniscus is associated with ACL insufficiency, while protrusion of the body and anterior horn of the lateral meniscus is a normal variant.     

The effect of allograft meniscal replacement on intraarticular contact area and pressures in the human knee. A biomechanical study

To define the biomechanical effects of total lateral meniscectomy and of subsequent lateral meniscal allograft replacement on load transmission and distribution across the human knee, we mounted 10 fresh-frozen young human cadaveric knees on a mechanical testing system. Peak pressure and contact area profiles were determined at 0 degrees, 30 degrees, and 60 degrees of knee flexion using pressure-sensitive film and a densitometer. Load transmission profiles were determined for each knee in a sequential test order: 1) intact knee, 2) after lateral meniscectomy, 3) after implantation of size-matched meniscal allograft fixed with bone plugs, and 4) after release of the anterior and posterior horn attachments of the allograft. Total lateral meniscectomy resulted in a 45% to 50% decrease in total contact area. Allograft replacement increased total contact area by 42% to 65% as compared with total meniscectomy at all flexion angles. After release of the anterior and posterior horn attachments, contact area was identical to that after total meniscectomy. Total lateral meniscectomy resulted in a 235% to 335% increase in peak local contact pressure. Allograft replacement decreased these pressures by 55% to 65% at all flexion angles, but they remained significantly greater than those in the intact state. After release of the anterior and posterior horn attachments, contact pressures were identical to those after total meniscectomy. Compared with total meniscectomy, meniscal allograft transplantation significantly increases contact area and decreases peak local contact pressures, but any biomechanical advantages are lost without bone plug fixation of the anterior and posterior horns.     

A topographically organized gamma-aminobutyric acid projection from the ventral pallidum to the nucleus accumbens in the rat

Anatomical and electrophysiological studies have indicated that a reciprocal projection from the ventral pallidum back to the nucleus accumbens exists and has functional relevance. In this study, the topographical projection from the ventral pallidum to the nucleus accumbens was examined by using retrograde tracing with fluoro-gold iontophoresed in subcompartments of the nucleus accumbens in rats combined with either in situ hybridization for glutamic acid decarboxylase and preproenkephalin mRNA or substance P immunoreactivity. Deposits made into the medial nucleus accumbens preferentially labeled neurons in the medial ventral pallidum, while deposits into the dorsolateral nucleus accumbens, at or lateral to the anterior commissure, labeled primarily cells in the dorsal and lateral ventral pallidum. A mediolateral to rostrocaudal topography was also observed, with the medial deposits preferentially labeling cells in rostral ventral pallidum and the lateral deposits resulting in retrogradely labeled cells in the ventral pallidum below the crossing of the posterior anterior commissure (subcommissural) as well as below the globus pallidus (sublenticular). The majority of cells retrogradely labeled with fluoro-gold were double-labeled for glutamic acid decarboxylase mRNA. In contrast, very few retrogradely labeled neurons in the ventral pallidum were double labeled for mRNA for preproenkephalin. These data demonstrate a topographically organized projection from the ventral pallidum to the nucleus accumbens that is primarily gamma-aminobutyric acid (GABA)-ergic and reciprocal to the GABAergic projection from the nucleus accumbens to the ventral pallidum.     

The mechanisms of psychological defense

Periventricular leucomalacia (PVL) is the most common form of hypoxemic brain damage in infants. In PVL, there is usually a preceding history of asphyxia or hypoxia. This results in hypoxic-ischaemic damage to the region of the brain around the lateral ventricles, a particularly vulnerable area as it is in a border zone between arterial supplies. PVL is usually first recognised as an echodense heterogenic flare in the anterior and posterior periventricular areas on brain ultrasound scan. This must clearly be differentiated from the typical halo seen in newborns. The formation of pseudocystic periventricular lesions is typically seen after 2 weeks. Thereafter, PVL is characterized by ventricular asymmetry with irregular walls or by cerebral atrophy. Age-specific neurological ultrasound findings are rarely seen in patients with PVL. As these individual developmental stages of PVL cannot always be found by ultrasound scan, the following criteria for diagnosis are recommended: Increased intense and heterogenic echodense areas followed by a breaking up of these echodense areas in the anterior and posterior periventricular regions on brain ultrasound scan. Multiple and thick-walled, initially non-communicating periventricular pseudocysts. Persistent typical asymmetrical dilatation of ventricles with irregular and blurred ventricular walls.     

Position and organization of thalamic cellular activity during diencephalic recording. I. Pressure-evoked activity

With the aid of a computer graphic display technique, data gathered from exploratory diencephalic recordings in 130 stereotactic operative procedures are presented to show the location and somatotopography of 'pressure'-evoked cellular responses. In addition, the variable position of these responses in relation to common diencephalic landmarks is presented. Our findings indicate that response points are more compact when related to a common posterior commissure (PC) and lie in a sickle-shaped zone 14-16 mm lateral to the midline and 2-8 mm rostral to anatomically the nucleus ventralis caudalis or the nucleus ventralis intermedius. Somatotopographically, face responses were medial to the leg.