View source for WBR1507

 {{WBRQuestion
|QuestionAuthor=William J Gibson
|ExamType=USMLE Step 2 CK
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|MainCategory=Internal medicine
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|SubCategory=Neurology
|MainCategory=Internal medicine
|MainCategory=Internal medicine
|SubCategory=Neurology
|Prompt=A 50 year old man with a history of end-stage renal failure presents to the hospital for head injury following a motor vehicle accident. The patient is unresponsive on admission. CT scan shows diffuse intraparenchymal hemorrhage. He is admitted to the neuro intensive care unit for further management. His blood pressure is 95/ . An epidural sensor is placed and the intracranial pressure is found to be  29 (Normal 5 - 15 mmHg). The patient is intubated and sedated with the head of the bed elevated. A central line and ventricular drain is placed, but the patient's ICP remains high at  28 mm Hg. What is the best next step to decrease this patient's intracranial pressure?
|Explanation=The patient in this vignette has elevated intracranial pressure as a result of traumatic brain injury (TBI). Intracranial pressure can be due to pressure in three compartments: the blood, the CSF or the brain. In this case, there is no discrete component of blood in the brain, and we have no reason to believe there is any obstruction of CSF flow that would increase the CSF pressure. Instead, it appears that there is swelling of the brain parenchyma causing increased intracranial pressure. Several maneuvers can work to decrease intracranial pressure in this case, including: 
- elevating the head of the bed
- positioning the patients head in a midline fashion to encourage venous outflow (otherwise jugular veins can be compressed)
- hyperosmolar agents

Dexamethasone would be unlikely to work in this case, as corticosteroids tend to work for cases of increased intracranial pressure due to tumors rather than trauma.
|AnswerA=Mannitol


|AnswerAExp=Mannitol is an effective agent for lowering intracranial pressure, but it is cleared by the kidneys and can precipitate renal failure. In a patient with pre-existing renal compromise mannitol would not be the best choice.
|AnswerB=Decompressive craniectomy
|AnswerBExp=Decompressive craniectomy is the last resort for elevated intracranial pressure. Not all other options have been exhausted in this case.
|AnswerC=Surgical evacuation of hematoma
|AnswerCExp=CT scan in this case revealed diffuse intraparenchymal hemorrhage. Unfortunately, there is no hematoma to evacuate in this case.
|AnswerD=Acetazolamide
|AnswerDExp=Acetazolamide is the therapy of choice in treating idiopathic intracranial hypertension. Acetazolamide . Also, keep in mind that his blood pressure is 105/70, meaning that his mean arterial pressure is 82.  Recall that the cerebral perfusion pressure is MAP-ICP = CPP. Therefore the cerebral perfusion pressure in this case is 54 (82-28). In the ICU, cerebral perfusion pressure is typically maintained between 50-70 mmHg. Lowering the patient's blood pressure further would put the patient at risk of cerebral hypoperfusion and ischemia.
|AnswerE=23% saline
|AnswerEExp=A 23% saline bolus would be the best option in this case. The saline bolus can help to increase the osmalirty of the serum, which can then draw blood out of the brain.
|EducationalObjectives=Hyperosmolar therapy is the best treatment for patient with elevated intracranial pressure and kidney failure.
|References=Stocchetti N, Maas AI. Traumatic intracranial hypertension. N Engl J Med. 2014;370(22):2121-30.
|RightAnswer=E
|WBRKeyword=NeuroICU
|Approved=No
}}