28 Neurosurgery MCQs Answers

Answer: a, b, d

Elevated intracranial pressure (ICP) contributes to secondary brain injury by reducing cerebral perfusion pressure which, by definition, is the difference between the mean arterial blood pressure and the cerebral venous pressure. For all clinically-relevant purposes, the cerebrovenous pressure is identical to ICP. Thus, when ICP increases and the mean arterial blood pressure remains stable, cerebral perfusion pressure decreases. When cerebral perfusion pressure falls below 70 mm Hg, cerebral blood flow is compromised, producing cerebral ischemia and compounding the primary injury with secondary insult. In studies of head injury mortality, intracranial hypertension appears to be one of the most important factors affecting outcome. For this reason, aggressive management to circumvent cerebral blood flow reduction and secondary injury is imperative. Initial clinical assessment is essential.

Although extensive neurologic testing is limited in uncooperative or unresponsive patients, certain features of examination are crucial. The Glasgow Coma Scale (GSC) uses a numerically scored elevated eye-opening and motor behavior, both spontaneously and in response to stimulation. The higher the score generated in assessment, the better the patient’s neurologic status. This scale also provides useful information regarding the ultimate outcome of the head-injured patient. ICP monitoring may be indicated especially in patients with marked depression or deterioration in neurologic function. Comatose patients who require emergent surgery for other injuries should also be monitored, since frequent neurologic assessment is not possible during general anesthesia. The steps in management to prevent ICP elevation include elevation of the head to facilitate venous return. Sedation reduces posturing and reflexively combative activity which both worsen ICP.

Hyperventilation keeps arterial carbon dioxide levels between 25 and 28 mm Hg and lowers cerebral blood volume and ICP. Mild dehydration with judicious sodium replacement and prompt treatment of inappropriate secretion of the antidiuretic hormone (SIADH) protects the brain from insult secondary to fluid overload. If ICP remains elevated despite these measures, mannitol, 0.5 to 1 g/kg and furosemide, 0.1 mg/kg can be used to reduce cerebral edema. Deep sedation with narcotics and even the use of paralyzing agents may be helpful. Corticosteroids are occasionally used, but have no proven benefit.

Category: Surgery MCQs