Symptomatic hamartoma of the spinal cord associated with neurofibromatosis type 1. Case report.

The authors present a case in which a symptomatic hamartoma was found in the spinal cord of a patient with neurofibromatosis type 1 (NF-1). This 52-year-old woman presented with painful urinary incontinence. Magnetic resonance (MR) imaging revealed an intramedullary lesion within the lower thoracic spinal cord and conus medullaris, which was surgically removed. Pathological investigation showed a hamartomatous lesion consisting of glial cells, ganglion cells, abundant disoriented axons, and thin-walled vessels. This case provides a pathological correlate to the hamartomatous lesions demonstrated on MR imaging in patients with NF-1 and illustrates that these benign lesions may become symptomatic and require neurosurgical intervention.

Spontaneous thrombosis of an unruptured anterior communicating artery aneurysm. An unusual cause of ischemic stroke.

BACKGROUND: Stroke caused by spontaneous thrombosis of an unruptured intracranial aneurysm is a rare event. CASE DESCRIPTION: A 66-year-old woman experienced a transient ischemic attack and cerebral infarctions due to spontaneous thrombosis of an unruptured anterior communicating artery aneurysm. Extension of thrombus into both anterior cerebral arteries and the left middle cerebral artery, resulting in ischemic infarction in all three vascular territories, was diagnosed by CT scanning, MRI, and cerebral angiography and confirmed at autopsy. CONCLUSIONS: This case illustrates a rare complication of an unruptured saccular aneurysm with neuroimaging and pathological correlation. Morphological and hemodynamic factors that may have precipitated aneurysm thrombosis are discussed with reference to experimental models.

Intraventricular hemorrhage complicating ventricular catheter revision: incidence and effect on shunt survival.

A retrospective study was conducted on 105 pediatric patients who underwent shunt revision between 1986 and 1993 at the Alberta Childrens Hospital (Calgary) to determine the frequency of intraventricular hemorrhage (IVH) with ventricular catheter revision. Ventricular catheter revision was performed 143 times in 74 patients. Intraventricular hemorrhage was noted intra-operatively or on post-operative computed tomographic (CT) scans on 45 occasions for an overall incidence of 31%. IVH was associated with a significantly shorter time (p < 0.0002) to subsequent shunt revision (227.33 +/- 392.24 days) compared to catheter survival when no hemorrhage was noted (735.02 +/- 1,001.11 days). This study raises several important questions about the prevention and management of IVH during shunt revision. It also provides the first published report on the incidence of IVH during shunt revision, thereby setting a standard to which future studies can be compared.

Arterial adaptations to altered blood flow.

Arterial remodeling in response to altered blood flow is believed to be critical to vascular adaptations to developmental, physiological, pathological, and therapeutically induced changes in blood flow. To assess this remodeling, we used left-to-right carotid anastomosis to increase blood flow in the right common carotid arteries of adult rabbits by 60%. After 2 months, these vessels exhibited no compensatory enlargement. In contrast, the same procedure performed in 5- to 6-week-old weanling rabbits resulted in accelerated growth of the vessels: diameters exceeded those of control arteries by 19% after 2 months. Common carotid arteries in adult rabbits remodeled to produce a diameter reduced by 23% when blood flow was reduced by 63% by external carotid ligation. This adaptation restored shear stress exerted on the vessel wall to control levels. The reduced diameter was not reversed when the vessels were maximally dilated with nitroprusside, adenosine, and forskolin; however, normal diameters were restored within 1 week when normal blood flows were reestablished. Thus, the adult arteries did not respond to increased blood flow produced by the anastomosis, but this procedure did reverse adaptations to decreased flow. In contrast, immature arteries were responsive to this increase in blood flow, even in the absence of prior flow modulation.

Perinatal aortic growth in lambs: relation to blood flow changes at birth.

We have examined aortic growth and aortic hemodynamics in lambs in the perinatal period. Morphometry of histological cross sections indicated that abdominal aortic circumference decreased by 31% between 131 days of gestation and 2-3 wk postpartum. In contrast, the internal circumference of the thoracic aorta increased by 34% over the same time interval; thus size reduction of the abdominal aorta was not part of a generalized arterial response to ex utero life. We also determined medial cross-sectional area as an index of medial tissue mass. In the perinatal period (120 days gestation to 21 days postpartum), this index increased by 144% for the thoracic aorta but only by 69% in the abdominal aorta. Differences in rate of medial tissue accumulation were much greater postpartum than in utero. The relationship between abdominal aortic growth and hemodynamic changes was examined by instrumenting fetal lambs with blood pressure catheters, abdominal aortic blood velocity transducers, and sonomicrometer diameter crystals mounted on the abdominal aorta. Parturition, and the consequent loss of the placental circulation, caused a 73% reduction in abdominal aortic blood velocity. Abdominal aortic external diameter in the period between 4 and 14 days postpartum was reduced significantly compared with in utero values. These data are consistent with the hypothesis that blood flow changes at birth significantly influence arterial growth postpartum.

Involvement of neuronal cell bodies of the mesencephalic locomotor region in the initiation of locomotor activity of freely behaving rats.

The locomotor activity of freely-moving rats was increased substantially by injections of L-sodium glutamate or of picrotoxin, a GABA antagonist, into the region of the tegmental pedunculopontine nucleus. The onset of hyper-motility was more rapid with L-glutamate than with picrotoxin and the duration shorter. Locomotor activity from injecting amphetamine unilaterally into the nucleus accumbens was reduced by injections of GABA into the ipsilateral pedunculopontine nucleus. These observations provide additional evidence implicating neurons of the MLR and possibly GABA synaptic inputs to these neurons in locomotor activity and suggest that they may mediate indirect inputs from the nucleus accumbens.