![]() ![]() The pupillary response to light should be examined in a dimly lighted room, where the pupils are naturally dilated. Baloh, Joanna Jen, in Goldman's Cecil Medicine (Twenty Fourth Edition), 2012 Examination of the Pupil Stimulation of the posterior pharynx with a tongue blade (gag reflex) and bronchial suctioning evaluates cranial nerves IX and X and should produce no response, such as gagging or coughing, in brain-dead patients. ![]() Pressure on the supraorbital nerve or any painful stimulus should not provoke grimacing in brain-dead patients. A blink response to corneal stimulation with a throat swab represents brainstem function and is inconsistent with brain death. The corneal reflex and response to pressure on the supraorbital nerve evaluates cranial nerves V and VII and should be absent in brain-dead patients. Facial Sensation and Facial Motor Response Aminoglycosides, sedatives, tricyclic antidepressants, anticholinergics, and antiepileptic medications can minimize or abort the caloric response. One minute of observation and 5 minutes between right and left stimulations are required. ![]() In brain-dead patients, there should be no response. In non–brain-dead patients, there is slow deviation to the cold caloric stimulus. Approximately 50 mL of ice water is injected through a small suction catheter directly into the ear canal. Caloric testing is undertaken after inspection visualizes the tympanic membrane and with the head at 30 degrees. Caloric testing is complementary to the preceding and necessary when the assessment of the oculocephalic reflex cannot be assessed by head turning because of cervical spine injury. In brain-dead patients, the eyes do not move and retain their orientation, which is termed the absence of doll's eyes. In non–brain-dead patients, the eyes deviate to the opposite side of the turning, which is termed the presence of doll's eyes. The oculocephalic reflex, or doll's eye reflex, which consists of vigorous rotation of the head from midposition to 90 degrees, should be undertaken only after cervical spine stability is ensured. Ocular MovementsĪny ocular movements, including nystagmus, should be absent in response to head turning or caloric testing, which evaluates cranial nerves III, VI, and VIII. Neuromuscular blockade should not affect pupillary reactivity atropine in conventional doses likewise should not affect reactivity. Although many drugs can affect pupil size, the response to light should be preserved. Round, oval, irregular, or dilated pupils are compatible with brain death, however, provided that they are not reactive. Most pupils in brain death are nonreactive and midposition. Pupillary response to bright light evaluates cranial nerves II and III and should be absent in both eyes. Wood, in Kidney Transplantation (Sixth Edition), 2008 Absence of Brainstem Reflexes Pupils ![]()
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