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)
What type of presentation results in brief loss of consciousness followed by a lucid interval and then progressive neurologic decline to obtundation, ipsilateral pupillary dilation (“blown pupil”), and contralateral hemiparesis (seen in 60% of cases).
Epidural hematoma
What is classic presentation of an epidural hematoma?
- Brief loss of conscious
- Then a lucid interval
- And then progressive neurologic decline to obtundation
- Ipsilateral pupillary dilation (“blown pupil”)
- Contralateral hemiparesis
What type of cranial injury crosses suture lines?
SDH
Timeline for acute, subacute, and chronic
(1) Acute: 0–48 hours; hyperdense on CT, although fresh uncoagulated blood may appear hypodense (see Fig. 20.1B)
(2) Subacute: 2–21 days; isodense on CT
(3) Chronic: ≥3 weeks; hypodense on CT (see Fig. 20.1C)
What is the surgical management for symptomatic acute SDH?
- Neurosurgical emergency
- Craniotomy to evacuate the lesion + hemicraniectomy to decompress the underlying injured brain.
What is the difference between craniotomy and craniectomy?
A Craniectomy is similar to a craniotomy as both procedures involve removing a portion of the skull, the difference is that after a craniotomy the bone is replaced and after a craniectomy the bone is not immediately replaced
How are hemorrhagic contusions treated?
Generally managed nonoperatively with neurologic observation and treatment of elevated ICP as indicated.
Surgical intervention is entertained when conservative medical management fails: decompressive craniectomy with or without resection of damaged brain.
Why does isolated temporal lobe contusion carry a high degree of mortality?
Patients with isolated temporal lobe contusion can proceed to herniation and death without clinical evidence of elevated ICP and must be monitored closely for neurologic decline.
Local temporal swelling results in uncal herniation.
What is the clinical sequelae of diffuse axonal injury?
Causes depression of consciousness or coma, but not associated with increases in ICP.
What is the “ring” or “halo” sign that is seen in neuro trauma?
Ring sign is the pattern on a bedsheet that is caused by a CSF leak. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3602259/
What type of skull fractures result in a CSF leak?
Skull base fractures
What are the signs of basilar skull fractures?
- Raccoon eyes: suggestive of fracture of the skull base at the floor of the anterior fossa or midfacial fractures
- Battle sign (also known as retroauricular hematoma)
- CSF otorrhea
- CSF rhinorrhea
When do depressed skull fractures require elevation? (4)
(a) Depressed greater than 8–10 mm or, generally, if the outer table of the skull is depressed below the inner table
(b) Deficit related to compression of the underlying brain
(c) CSF leak from wound due to dural laceration
(d) Open, depressed skull fracture due to risk for intracranial infection
What is the percentage of patients who experience blunt TBI with a presentation GCS =3 that will survive?
20%
What do you look for in the secondary survey when you log roll the patient?
To palpate the spine and to look for:
- Obvious deformities
- Open wounds
- Step offs
- Deformities
- Tenderness
What happens in spinal shock?
- Causes loss of sympathetic tone which results in a distributive shock
What are the signs of spinal shock? (4)
- Hypotension with bradycardia
- Warm extremities due to peripheral vasodilation
- Loss of reflexes
- Flaccid paralysis
What is the bulbocavernous reflex?
Anal sphincter contraction in response to glans penis pinch or foley catheter tug
What is the value of bulbocavernous reflex?
May signify resolution of the shock period.
Absence of the bulbocavernosus reflex (anal sphincter contraction in response to glans penis pinch or Foley catheter tug) in a patient with spinal shock has prognostic value and its return may signify resolution of the shock period.
Why do high cervical cord injuries require intubation/tracheostomy?
This is due to the impairment of phrenic nerve function.
How many vertebrae are there in the cervical spine?
7
How many vertebrae are there in the thoracic spine?
12
How many vertebrae are there in the lumbar spine?
5
How many vertebrae are there in the sacral spine?
5
How many vertebrae are there in the coccyx spine?
4
What is the vasopressor of choice in spinal shock?
Dopamine, but also phenylephrine
What is the MAP goal for spinal shock? How many days do they have to have this MAP target?
Goal is to maintain MAP ≥85 for first 7 days after injury to provide for adequate perfusion of spinal cord; hypotension may further injure the spinal cord.
At what level of injury does traumatic cauda equina syndrome occur?
L1-2
What are the characteristics of traumatic cauda equina syndrome?
- Bilateral paraparesis of the lower extremities
- Areflexia alternating or bilateral radiculopathy
- Disturbance of bowel and bladder function (urinary retention, rectal sphincter incompetence)
When should cervical spine fractures be suspected?
For any injury above the clavicle
14) In a blunt trauma victim, persistent hypotension despite vigorous fluid resuscitation may be indicative of all of the following, EXCEPT?
a. tension pneumothorax
b. pericardial tamponade
c. ongoing intracranial hemorrhage
d. myocardial infarction
C
How is cerebral salt wasting different from SIADH?
In CSW you get hypovolemia whereas in SIADH you have hyper/normovlemia.
You also increased urine output in CSW but decreased in SIADH
What is a Hangman’s fracture?
“Hangman’s fracture” is fracture of bilateral pars interarticularis of axis (C2) that disrupts C2–3, often resulting in subluxation.
