Endoscopic aqueductal plasty via the fourth ventricle through the cerebellar hemisphere under navigating system guidance--technical note.
A 1-year 8-month-old boy presented with isolated fourth ventricle after ventriculoperitoneal shunting for hydrocephalus associated with ventricular and subarachnoid hemorrhage. The therapeutic endoscope was inserted through the thin left cerebellar hemisphere. Endoscopic aqueductal plasty was performed via the enlarged fourth ventricle under guidance from a navigating system. Endoscopic aqueductal plasty via the fourth ventricle under navigating system guidance is a useful procedure enabling less invasive surgery for isolated fourth ventricle associated with slit-like ventricle after shunt placement. (+info
Kainic acid lesions to the lateral tegmental field of medulla: effects on cough, expiration and aspiration reflexes in anesthetized cats.
We have tested the hypothesis that neurons of both the ventral reticular nucleus and the adjacent parts of the lateral tegmental field (LTF) may be important for the production of motor programs associated with cough, expiration and aspiration reflexes. Our studies were conducted on non-decerebrate, spontaneously breathing cats under pentobarbitone anesthesia. Dysfunction of the medullary LTF region above the obex, produced by uni- or bilateral injections of kainic acid (a neurotoxin), regularly abolished the cough reflex evoked by mechanical stimulation of both the tracheobronchial and laryngeal regions and in most cases also the expiration reflex induced from the glottal area. However, some electrical activity still occurred in the neurogram of the recurrent laryngeal nerve during probing the laryngeal and glottal regions. Interestingly, the aspiration reflex elicited from the nasopharynx regularly persisted, although with lower intensity after the LTF lesion. Nevertheless, successive midcollicular decerebration performed in four cats also abolished the aspiration reflex. These experiments demonstrate the importance of medullary LTF neurons for the normal occurrence of cough and expiration reflexes. One possible explanation for the elimination of these expulsive processes is that the blockade of the LTF neurons may remove an important source of a facilitatory input to the brainstem circuitries that mediate cough and expiration reflexes. In addition, the potential importance of the mesencephalic reticular formation for the occurrence of the aspiration reflex and the role of the LTF in modulating both the eupnoeic breathing and the blood pressure are also discussed. (+info
Hypoglycemia activates orexin neurons and selectively increases hypothalamic orexin-B levels: responses inhibited by feeding and possibly mediated by the nucleus of the solitary tract.
Orexins are novel appetite-stimulating peptides expressed in the lateral hypothalamic area (LHA), and their expression is stimulated by hypoglycemia in fasted rats. We investigated activation of orexin and other neurons during insulin-induced hypoglycemia using the immediate early gene product Fos. Insulin (50 U/kg) lowered plasma glucose by >50% after 5 h and stimulated feeding sixfold compared with saline-injected controls. Hypoglycemic rats allowed to feed and normoglycemic controls both showed sparse Fos-positive (Fos+) neurons in the LHA and the paraventricular nucleus (PVN) and arcuate nucleus (ARC) and showed none in the nucleus of the solitary tract (NTS), which relays visceral feeding signals to the LHA. In the LHA, total numbers of Fos+ neurons were comparable in fed hypoglycemic and control groups (60 +/- 6 vs. 52 +/- 4 cells/mm2, P > 0.05), as were Fos+ neurons immunoreactive for orexin (1.4 +/- 0.4 vs. 0.6 +/- 0.4 cells/mm2, P > 0.05). By contrast, hypoglycemic rats that were fasted showed significantly more Fos+ nuclei in the LHA (96 +/- 10 cells/mm2, P < 0.05, vs. both other groups) and Fos+ orexin neurons (8.4 +/- 3.3 cells/mm2, P < 0.001, vs. both other groups). They also showed two- to threefold more Fos+ nuclei (P < 0.001) in the PVN and ARC than both fed hypoglycemic rats and controls and showed strikingly abundant Fos+ neurons in the NTS and dorsal motor nucleus of the vagus. In parallel studies, whole hypothalamic orexin-A levels were not changed in hypoglycemic rats, whether fasted or freely fed, whereas orexin-B levels were 10-fold higher in hypoglycemic fasted rats than in control and hypoglycemic fed groups. These data support our hypothesis that orexin neurons are stimulated by falling glucose levels but are readily inhibited by signals related to nutrient ingestion and suggest that they may functionally link with neuronal activity in the NTS. Orexin-A and -B may play specific roles in behavioral or neuroendocrine responses to hypoglycemia. (+info
Midline posterior fossa teratoma--case report.
A 20-day-old female neonate presented with an immature teratoma in the midline posterior fossa. The tumor was totally removed but the patient died of pneumonia. Teratoma is a rare tumor, but very difficult to treat as the patients tend to be young, and the outcome is very poor. (+info
Subdiaphragmatic vagotomy induces NADPH diaphorase in the rat dorsal motor nucleus of the vagus.
Axotomy of the vagal motor neurons by cervical vagotomy induces NADPH diaphorase staining due to increased nitric oxide synthase expression in both the rat dorsal motor nucleus and nucleus ambiguous; furthermore, cerical vagotomy leads to cell death of the dorsal motor nucleus cells. Subdiaphragmatic vagotomy axotomizes the vagal motor cells further from the brainstem than cervical vagotomy, and cuts the fibers running only to the abdominal viscera. Here we report that subdiaphragmatic vagotomy is sufficient to induce NADPH diaphorase staining in the dorsal motor nucleus but does not induce staining in the nucleus ambiguus. Because the neurons of the dorsal motor nucleus do not undergo cell death after subdiaphragmatic vagotomy and are able to re-enervate the gut, the increased nitric oxide synthase expression after distal axotomy may be related more to regeneration than degeneration. (+info
Fourth ventricular meningioma in an adult--case report.
A 72-year-old female presented with an intra-fourth ventricular meningioma manifesting as truncal ataxia. Computed tomography (CT) showed a slightly high-density, well-demarcated, and homogeneously enhanced mass located in the fourth ventricle and extending to the right lateral recess. T2-weighted magnetic resonance (MR) imaging revealed a peritumoral high-intensity band without dural tail sign. Bilateral vertebral angiography revealed faint tumor staining supplied from the choroidal branches of the posterior inferior cerebellar arteries. The mass was totally resected via a suboccipital approach. CT, T2-weighted MR imaging, and vertebral angiography are informative for the preoperative diagnosis of fourth ventricular meningioma. (+info
Intracranial meningeal involvement in Churg-Strauss syndrome.
We describe the case of a 54-year-old woman with a clinical diagnosis of Churg-Strauss syndrome (CSS). The patient had a fever of unknown origin, severe headache, progressing left ophthalmoplegia, and visual acuity disturbance. MR imaging revealed diffuse and thick hypointense lesions on T2-weighted images in the frontal meninges and anterior falx cerebri with diffuse enhancement. Similar lesions were also detected in the left superior ophthalmic fissure to the cavernous sinus. Nodular lesions in the fourth ventricle, which might have been the cause of hydrocephalus, were hypointense on T2-weighted images. These MR imaging findings suggested remote granulomatous involvement in the meninges and choroid plexus associated with CSS. To our knowledge, remote meningeal involvement in association with CSS has not been previously reported. (+info
Intractable vomiting from glioblastoma metastatic to the fourth ventricle: three case studies.
Dissemination of malignant glioma to the fourth ventricle with metastatic deposits and intractable vomiting is rare. Leptomeningeal extension of malignant glioma is an uncommon condition that has been reported in patients with end-stage disease and is usually unresponsive to any treatment modality. We describe 3 patients with progressing recurrent glioblastoma multiforme in whom leptomeningeal invasion manifested itself as intractable vomiting due to tumor metastases in the floor of the fourth ventricle. All patients received additional radiation therapy focused to the posterior fossa, with complete resolution of vomiting occurring within 10 days after irradiation. The remission of symptoms in these patients persisted until their death 3-4 months after the repeat radiation therapy. These reports indicate that additional focused radiation should be considered because of its significant therapeutic effect in alleviating intractable nausea and vomiting in patients with glioma metastasized to the posterior fossa. (+info