The trigemino-cardiac reflex (TCR) is clinically defined as the sudden onset of parasympathetic activity, sympathetic hypotension, apnea, or gastric hypermotility during central or peripheral stimulation of any of the sensory branches of the trigeminal nerve. Clinically, the TCR has been reported to occur during craniofacial surgery, manipulation of the trigeminal nerve/ganglion and during surgery for lesion in the cerebellopontine angle, cavernous sinus, and the pituitary fossa. Apart from the few clinical reports, the physiologic function of this brainstem reflex has not yet been fully explored. The manifestation of the TCR can vary from bradycardia and hypotension to asystole. From the experimental findings, the TCR represents an expression of a central reflex leading to rapid cerebrovascular vasodilatation generated from excitation of oxygen-sensitive neurons in the rostral ventro-lateral medulla oblongata. By this physiologic response, the systemic and cerebral circulations may be adjusted in a way that augments cerebral perfusion. This review summarizes the current state of knowledge about TCR.
We present the first report of peripheral stimulation of a sensory branch of the trigeminal nerve that leads to a TCR under general anaesthesia according to our strict criteria as defined in 1999. The present finding is therefore a key research development and gives substantial evidence that TCR is coincident enhancement of sympathetic and parasympathetic outflows to the heart, suggesting that genetic differences may affect the susceptibility for TCR.
Artwork courtesy of Julie Gilbert Pollard. Impatiens by the Creek (detail). Watercolor on paper, 12" × 12". Background: Cerebrospinal fluid (CSF) is found around and inside the brain and vertebral column. CSF plays a crucial role in the protection and homeostasis of neural tissue. Methods: Key points on the physiology of CSF as well as the diagnostic and treatment options for hydrocephalus are discussed. Results: Understanding the fundamentals of the production, absorption, dynamics, and pathophysiology of CSF is crucial for addressing hydrocephalus. Shunts and endoscopic third ventriculostomy have changed the therapeutic landscape of hydrocephalus. Conclusions: The treatment of hydrocephalus in adults and children represents a large part of everyday practice for the neurologist, both in benign cases and cancer-related diagnoses. Cerebrospinal Fluid Production Approximately 70% of cerebrospinal fluid (CSF) is produced by the choroid plexus of the lateral ventricles and the tela choroidea of the third and fourth ventricles. 1 There is also extrachoroidal secretion of CSF by the epithelium of the ependyma and by the capillaries via the blood-brain barrier. Choroid plexus can develop as early as the 41st day in the embryo. 2 In general, the volume of CSF in an adult is approximately 150 mL (125 mL in the subarachnoid space, 25 mL
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