on leading to the paralysis, diminution in respiratory rate, elevation in systolic blood pressure, increase in pulse pressure, elevation of body temperature, inaudible speech and restiveness, convulsions and abnormal posturing.
Cerebrovascular auto-regulation is the ability of brain to keep the flow of cerebral blood constant even though there are alterations in cerebral perfusion pressure (CPP). The mechanism is disrupted due to any kind of injury in the head, from mild to severe. Unfavourable outcome may result when head injury is followed by poor auto-regulation, indicating that the mechanism protects the brain against perfusion pressure-related secondary insults. It is therefore auto-regulation is determined in patients with traumatic brain injury. Auto-regulation is determined by assessing CBF, measured by transcranial Doppler (TCD) used for static and dynamic measurement of auto-regulation, other methods encompass cerebral metabolic rate for oxygen (CMRO2), waveform analysis, arterio-jugular oxygen content difference (AJDO2) (Steiner, 2003).
The oculovestibular reflex is tested by caloric stimulation using irrigation with ice water. In normal subjects jerk nystagmus is elicited for about 2-3 minutes with slow component towards the irrigated ear. In unconscious patients with intact brainstem, the fast component of nystagmus disappears so that eyes are tonically deviate towards irrigated side for 2-3 minutes before returning to their original position. With impaired brainstem function the response becomes perverted and finally disappears. In metabolic coma, oculocephalic and oculovestibular reflex responses are preserved at least initially.
White matter- composed of Myelinated nerve fibers. In these nerve fibers, the speed of action potential is very high. These neurons convey the action potential from sensory receptor to CNS (sensory neuron) or from CNS to effector organ (Motor