Neurology/Neurosurgery Flashcards
What type of fluids should be avoided in a neurotrauma patient?
Hypotonic fluids can exacerbate cerebral edema and should be avoided in fluid resuscitation of the neurotrauma patient.
How do you calculate the cerebral perfusion pressure?
Cerebral perfusion pressure (CPP) = mean arterial pressure (MAP) − intracranial pressure (ICP); goal is to maintain MAP ≥60 mm Hg because CPP <60 mm Hg can confound assessment of level of consciousnes
What are the three kinds of an “unconscious state”?
- Bilateral dysfunction of the cerebral hemispheres
- Bilateral dysfunction of the diencephalon
- Depression of the reticular activating system (midbrain and pons)
How do supratentorial mass lesions cause deterioration of conscious?
1) Direct compression of brain and, eventually, brainstem
(2) Progressive deterioration of level of consciousness
(3) Symmetric deterioration suggests central herniation syndrome, whereas asymmetric decline suggests uncal or subfalcine herniation.
How do infratentorial mass lesions cause deterioration of consciousness?
Direct compression of reticular activating system resulting in rapid onset and progression to coma
What are the 6 electrolyte or endocrine imbalances that lead to a coma?
- Hyponatremia
- Hypoglycemia
- Hyperammonemia
- DKA
- Myxedema
- Kernicterus
What two types of nutritional deficiency lead to a coma?
- B12 deficiency
- Thiamine deficiency
What type of inherited metabolic disorder cause a coma?
Porphyria
What type of lesion leads to flexor/decorticate posturing?
Lesion above the red nucleus (midbrain)
What type of lesion leads to extensor/decerebrate posturing?
Lesion above the lateral vestibular nucleus but below the red nucleus
What is the sign on CT that is seen in subfalcine herniation?
Midline shift
What is the GCS score for mild TBI?
GCS 13-15
What is the GCS score for moderate head injury?
GCS 9-12
What type of head injuries are associated with skull fractures?
Often associated with skull fractures and/or multiple traumatic intracranial injuries
What is the GCS score for severe head injury?
GCS </= 8
What is the cushing triad?
Hypertension
Bradycardia
Respiratory Irregularities
This is when you suspect elevated ICP
What is a normal ICP?
0 - 15 mmHg
At what intracranial pressure is treatment indicated?
ICP > 20-25 mmHg for 15-30 min
What are 6 Tier 1 treatments for an elevated ICP?
(1) Optimize positioning by elevating head of bed to 30 degrees.
(a) This can be performed in reverse Trendelenburg with head of bed flat in cases of spine precautions.
(2) Maintain head in neutral position (not rotated or flexed) and ensure cervical collar is not compressing anterior neck to promote jugular venous outflow.
(3) Ensure adequate sedation with short-acting agents that allow frequent neurologic examination (e.g., propofol, fentanyl).
(4) Maintain normothermia and treat fevers; there is currently limited level III evidence for improved outcomes with prophylactic hypothermia such that it remains controversial and under active investigation.
(5) Avoid hypotension by maintaining systolic blood pressure ≥90 mm Hg and MAP ≥65 mm Hg.
(6) Avoid hypoxia by maintaining oxygen saturation (SaO 2) ≥90%; minimize positive end-expiratory pressure (PEEP) as clinically feasible to promote jugular venous drainage by decreasing intrathoracic pressure.
What are the Tier II treatments for elevated ICP?
- Osmotic Therapy
- CSF diversion via EVD for elevation of ICP to reduce volume of ventricular system
- Maintain CPP greater than 50–60 mm Hg.
- Hyperventilation causes alkolosis, which results in cerebral vasoconstriction. By causing cerebral vasoconstriction, intracranial intravascular volume is reduced, which reduces cerebral perfusion. However, this is only a temporary measure.
- Glucocorticoid administration is contraindicated
What are the Tier III treatments for elevated ICP?
(1) Barbiturate-induced coma; performed in conjunction with continuous EEG monitoring of burst suppression. Avoid hypotension.
(2) Nondepolarizing paralytics
(3) Operative decompression (e.g., hemicraniectomy)