Head Trauma Medical Question:
A 25 year old male is found at the scene of a motor vehicle accident with fracture of both his lower extremities. You also note extensive abdominal bruising and scalp laceration. At the scene of the accident, the patient’s blood pressure is 85/60 mmHg and his heart rate is 122/min. He is given 2L of IV fluids. On the way to the hospital he becomes progressively drowsy, and develops progressive weakness on the right side of his body. This patient is also likely to show deficits in the functioning of which of the following nerves?
References for this head trauma question:
–USMLEWORLD,LLC QBank ver 2009.02
Correct answer is: C. Oculomotor. The nature of this patient’s accident and his scalp lacerations suggest that he has suffered blunt head trauma. After initial fluid resuscitation, he lapses into a state of decreased consciousness with right-sided hemiparesis. The most likely explanation in this setting is a transtentorial (uncal) herniation secondary to a right sided epidural hematoma. Transtentorial herniation of the parahippocampal uncus causes: Ipsilateral hemiparesis due to compression of the contralateral cerebral peduncle against the tentorium, Ipsilateral Mydriasis and strabismus due to compression of the Ipsilateral oculomotor nerve, contralateral hemianopia due to compression of the Ipsilateral posterior cerebral artery and altered consciousness due to compression of the reticular formation.