A Whole-brain Map of Long-range Inputs to GABAergic Interneurons in the Mouse Caudal Forelimb Area.

The caudal forelimb area (CFA) of the mouse cortex is essential in many forelimb movements, and diverse types of GABAergic interneuron in the CFA are distinct in the mediation of cortical inhibition in motor information processing. However, their long-range inputs remain unclear. In the present study, we combined the monosynaptic rabies virus system with Cre driver mouse lines to generate a whole-brain map of the inputs to three major inhibitory interneuron types in the CFA. We discovered that each type was innervated by the same upstream areas, but there were quantitative differences in the inputs from the cortex, thalamus, and pallidum. Comparing the locations of the interneurons in two sub-regions of the CFA, we discovered that their long-range inputs were remarkably different in distribution and proportion. This whole-brain mapping indicates the existence of parallel pathway organization in the forelimb subnetwork and provides insight into the inhibitory processes in forelimb movement to reveal the structural architecture underlying the functions of the CFA.

Congenital cavernous angioma exhibits a progressive decrease in size after birth.

CASE REPORT: We report a case of congenital intracranial cavernous angioma, which was initially found at a gestational age of 34 weeks in utero as a mass lesion associated with hydrocephalus. After birth, the patient was treated for hydrocephalus first by external drainage and then by ventricular peritoneal shunt. The natural course of the mass lesion was observed until the age of 8 months when the histopathological diagnosis confirmed the cavernous angioma after tissue was obtained by surgery. CT scans repeated monthly during this period demonstrated that the angioma continuously decreased in size. There was no evidence of hemorrhage in the angioma on serial CT scans. The histopathology revealed thrombosis of cavernous vessels with hyaloid changes in the angioma. DISCUSSION: The mechanisms of the decreasing size of the cavernous angioma have often been discussed in relation to spontaneous hemorrhages and resolution. The present case suggests a mechanism in which the spontaneous formation of a thrombus might be the dominant factor for the decrease in size. Thrombus formation may result from low perfusion due to the large size of the angioma.

[Bilateral hypoxic-ischaemic thalamic lesions in newborns]. / Bilaterale hypoxisch-ischämische Thalamusläsionen im Neugeborenenalter.

Bilateral hypoxic-ischaemic thalamic lesions are a rare type of neonatal encephalopathy with characteristic but often misinterpreted clinical features. This article describes history, clinical and diagnostic findings in a preterm and a term infant with hypoxic-ischaemic thalamic lesions after severe and abrupt intrauterine hypoxia. Both neonates presented with absent suckling and swallowing whereas other cranial nerves were unaffected. Characteristic findings in both newborns were profound muscular hypotonia and weak facial expressions together with feeding difficulties and frequent episodes of aspiration pneumonias. The term infant died at the age of 14 weeks following presumed aspiration pneumonia, the preterm infant, however, has developed severe extrapyramidal cerebral palsy. Absent suckling and swallowing with otherwise normal cranial nerve function appears to be characteristic of a bilateral hypoxic-ischaemic lesion of the thalamus. Animal experiments suggest that these lesions originate from a short but total ischaemia as it can be observed in cord prolapse or total placental abruption. Specific findings may initially be absent on ultrasound examination. Hence, magnetic resonance imaging of the brain should be performed on all patients with characteristic clinical symptoms even if the ultrasound scan is unremarkable. Evidence of bilateral ischaemic lesions of the thalamus usually indicates a poor prognosis.

Perinatal hypoxic-ischemic thalamic injury: clinical features and neuroimaging.

A common pattern of hypoxic-ischemic cerebral injury in the term newborn involves predominantly cerebral cortex and subcortical white matter. We describe 20 term newborns with moderate or severe acute hypoxic-ischemic encephalopathy who exhibit a different pattern of abnormalities on computed tomography, with evidence of decreased tissue attenuation predominantly in thalami and basal ganglia and relative preservation of cerebral cortex and white matter. Profound, acute hypoxic-ischemic insult (eg, umbilical cord prolapse, uterine rupture, or massive placental abruption) was documented in 16 of 20 infants (80%). Characteristic clinical features during the newborn period included irritability, tonic posturing of limbs, and persistent lower cranial nerve dysfunction, often with prominent tongue fasciculations. This pattern of central injury appears to be highly predictive of poor outcome; 7 newborns (35%) died, and all survivors who had follow-up to 18 months of age (11) had major neurological sequelae (eg, spastic quadriplegia, choreoathetosis, and persistent feeding problems). This pattern of hypoxic-ischemic cerebral injury corresponds closely to experimental animal models of "acute total" perinatal asphyxia.

[The effect of lesions of different parts of the optic thalamus on the nature of the bioelectrical activity of the human brain]. / Vliianie porazheniia razlichnykh otdelov zritel'nogo bugra na kharakter bioélektricheskoi aktivnosti mozga cheloveka.

The EEG recordings of 41 patients with thalamic arteriovenous malformations (AVM) were studied by means of multivariate statistical analysis. In 16 patients the AVM were located in pulvinar, in 17 patients in the ventrolateral, in 4 patients in the medial, and in the remaining 4 patients in the anterior thalamic regions. Pathological EEG signs were visually classified and subjected to analysis of variance. The EEG signs were separated caused by the lesion localization. It was shown that the lesions in the posterior thalamus resulted in the alpha-rhythm suppression up to its total elimination. It was substituted for the bilateral local pathological activity in the posterior areas of the hemispheres. The diffuse beta-activity was observed. The ventrolateral and medial thalamic lesions led to the alpha-rhythm disorganization and its exaltation. The local slow waves were revealed in the sensorimotor cortical areas. The diffuse slow activity was observed as well as the signs of diencephalic irritation in the form of bilaterally synchronous bursts of activity in the alpha-theta range.

[The microsurgical treatment of arteriovenous malformations of the thalamus]. / Mikrokhirurgicheskoe lechenie arteriovenoznykh mal'formatsii zritel'nogo bugra.

The article analyzes the clinical data of 48 patients with arteriovenous malformations of the thalamus, who were examined at the Burdenko Institute of Neurosurgery, AMS USSR, from 1970 to 1989. The experience in surgical treatment is based on 25 cases. The authors describe in detail the indications for surgical treatment, adequate surgical approaches, and the method for removal of the malformations. Neuropsychological and electrophysiological methods of examination of patients in dynamics were applied to evaluate the results of surgery.

Symmetrical thalamic degeneration with calcifications of infancy.

We describe the clinical and radiographic features of three premature infants with symmetric thalamic calcification recognized by computed tomographic scan on days 6, 12, and 49 of life and contrast our findings with those reported in the literature. These lesions follow prepartum or intrapartum hypoxiaischemia and are clinically distinguished by prominent bulbar dysfunction, featuring weak or absent cry, poor feeding, and facial weakness. Neonatal thalamic calcification in premature infants may serve as a radiological marker of an acute, short-lived hypoxic-ischemic event. The presence of brain-stem dysfunction, particularly of lower cranial nerves in association with thalamic calcifications, constitutes a distinctive clinical-radiological entity and usually portends a poor outcome. The presence of these calcifications implies that injury was sustained to diencephalic and brain-stem structures at least 2 to 4 weeks prior to their appearance on computed tomographic scan.

Axonal dystrophy in a case of connatal thalamic and brain stem degeneration.

A neonate with a rapidly fatal disease characterized by connatal hypertonia and arthrogryposis multiplex is described. Neuropathological investigations revealed bilateral thalamus and brain stem degeneration, axonal degeneration of pyramidal and other tracts in the spinal cord, and axonal spheroids in areas of origin of lower motor neurons and in the brain stem reticular substance. Congenital thalamic and brain stem degeneration is generally assumed to be the result of intrauterine asphyxia. The widespread occurrence of axonal spheroids in the present neonate points to the possibility of a genetic or toxic origin for at least some of these cases.

Prenatal symmetrical thalamic degeneration with flexion spasticity at birth.

The unusual occurrence of spasticity at birth with symmetrical thalamic damage was found in a male infant delivered at 36 weeks' gestation following an episode of traumatically induced premature labor at 32 weeks. The infant was found to be spastic in flexion with increased stretch reflexes, depressed primitive reflexes, and moderate flexion contractures. Computerized tomographic scans showed bilateral nonenhancing thalamic densities. Neuropathologically, the lateral thalamic nuclei and the red nucleus showed neuron loss, astrocytosis, and, as confirmed by electron microprobe analysis, calcified neurons. The striatum was uninvolved. These findings closely resemble those reported as "symmetrical thalamic degeneration in infancy" and are strongly reminiscent of the pattern of thalamic involvement frequently seen in status marmoratus. It would appear that there is a period during perinatal life in which the lateral thalamus can be rendered vulnerable to hypoxic-ischemic injury, and that the thirty-second week of gestation must be included within this period.