Neurotrophin-3 modulates noradrenergic neuron function and opiate withdrawal.

Somatic symptoms and aversion of opiate withdrawal, regulated by noradrenergic signaling, were attenuated in mice with a CNS-wide conditional ablation of neurotrophin-3. This occurred in conjunction with altered cAMP-mediated excitation and reduced upregulation of tyrosine hydroxylase in A6 (locus coeruleus) without loss of neurons. Transgene-derived NT-3 expressed by noradrenergic neurons of conditional mutants restored opiate withdrawal symptoms. Endogenous NT-3 expression, strikingly absent in noradrenergic neurons of postnatal and adult brain, is present in afferent sources of the dorsal medulla and is upregulated after chronic morphine exposure in noradrenergic projection areas of the ventral forebrain. NT-3 expressed by non-catecholaminergic neurons may modulate opiate withdrawal and noradrenergic signalling.

Magnetic source imaging and brain surgery: presurgical and intraoperative planning in 26 patients.

OBJECT: The availability of large-array biomagnetometers has led to advances in magnetoencephalography that permit scientists and clinicians to map selected brain functions onto magnetic resonance images. This merging of technologies is termed magnetic source (MS) imaging. The present study was undertaken to assess the role of MS imaging for the guidance of presurgical planning and intraoperative neurosurgical technique used in patients with intracranial mass lesions. METHODS: Twenty-six patients with intracranial mass lesions underwent a medical evaluation consisting of MS imaging, a clinical history, a neurological examination, and assessment with the Karnofsky Performance Scale. Magnetic source imaging was used to locate the somatosensory cortex in 25 patients, the visual cortex in six, and the auditory cortex in four. The distance between the lesion and the functional cortex was determined for each patient. Twenty-one patients underwent a neurosurgical procedure. As a surgical adjunct, a frameless stereotactic navigational system was used in 17 cases and a standard stereotactic apparatus in four cases. Because of the results of their MS imaging examination, two patients were not offered surgery, four underwent a stereotactic biopsy procedure, 10 were treated with a subtotal surgical resection, and seven were treated with complete surgical resection. One patient deteriorated before a procedure could be scheduled and, therefore, was not offered surgery, and two patients were offered surgery but declined. Three patients experienced surgery-related complications. CONCLUSIONS: Magnetic source imaging is an important noninvasive neurodiagnostic tool that provides critical information regarding the spatial relationship of a brain lesion to functional cortex. By providing this information, MS imaging facilitates a minimum-risk management strategy and helps guide operative neurosurgical technique in patients with intracranial mass lesions.

Intracranial vascular anastomosis using the microanastomotic system. Technical note.

The authors describe the use of a microanastomotic device to perform intracranial end-to-end vascular anastomoses. Direct end-to-end anastomosis was performed between the superficial temporal artery and branches of the middle cerebral artery (MCA) in three patients. Two patients had moyamoya disease, with severe proximal MCA disease, and one suffered an internal carotid artery occlusion with poor collateral flow. All patients reported a history of recent ischemic symptoms. Each anastomosis was accomplished in less than 15 minutes with technically satisfactory results. Postoperative angiographic studies demonstrated patency of the bypasses in all patients.

Revascularization and bypass procedures for cerebral aneurysms.

Revascularization and bypass procedures are useful in the treatment of complex aneurysms. Extracranial to intracranial bypass grafts are used to augment the distal circulation as an adjunct to proximal vessel occlusion for aneurysm treatment. Bypass grafts are used also to ensure adequate distal circulation during aneurysm trapping procedures. Recent improvements in vascular exposures at the skull base have allowed the development of vessel replacement or interposition grafts for arteries harboring aneurysms at the skull base. Intracranial interposition grafts are used to reconstruct arteries harboring aneurysms that cannot be occluded directly using clip or coil techniques. These techniques in the treatment of cerebral aneurysms are discussed.

Survival of adult 5-HT neurons following intraocular transplantation.

The present study was undertaken to provide an improved environment in which to examine the capacity of more mature CNS tissue to survive following transplantation. Tissue containing serotonin (5-HT) neurons from nucleus raphe dorsalis of 4- and 8-week-old rats was transplanted to the anterior chamber of the eye. Baseline conditions were improved by minimizing the time of the grafting procedure and enhancing the nutrition and oxygenation of the grafting medium. Additional treatment of the grafts during the 4 weeks of in oculo development included either: (1) intermittent hyperbaric oxygen (HBO), (2) continuous hyperoxia, or (3) control. In vivo measurement revealed that all grafts decreased significantly in size, a majority of which still demonstrated a small degree of vascularization. Microscopically, a significant percentage of the grafts demonstrated 5-HT-immunoreactive (5-HT-ir) fiber outgrowth into the host irides, although 5-HT-ir cell bodies could not always be discerned. In terms of percentage of grafts with surviving 5-HT-ir fibers, the best results were seen with the grafts treated with continuous hyperoxia (3 out of 4), as compared to HBO-treated grafts (4/18) and the control group (3/24). For both the HBO-treated and control groups, slightly better results were seen with 4-week-old vs 8-week-old donor tissue. The density and the surface area covered by the 5-HT-ir fibers was not correlated with either treatment or donor age. Thus, while continuous hyperoxia or HBO treatment may have a positive effect, the enhanced baseline conditions appear to provide an environment in which to demonstrate that 5-HT neurons from 4- and 8-week-old rats possess the capacity to survive transplantation.