Neurosurgery Flashcards
What is the incidence of head trauma?
70,000 fatal injuries per year in US (500,000 head injuries)
What percentage of trauma deaths result from head trauma?
50%
What is the Glasgow Coma Scale?
Objective assessment of the level of consciousness after trauma
What does unilateral, dilated, nonreactive pupil suggest?
Focal mass lesion with ipsilateral herniation and compression of CN III
What do bilateral fixed and dilated pupils suggest?
Diffusely increased ICP
What are the 4 signs of basilar skull fracture?
- Raccoon eyes (periorbital ecchymoses)
- Battle’s sign (postauricular ecchymoses)
- Hemotympanum
- CSF rhinorrhea or otorrhea
What is the initial radiographic neuroimaging in trauma?
- Head CT (if LOC or GCS < 15)
- C-spine CT
- T/L spine AP and lateral
Should the trauma head CT be with or without IV contrast?
Without
What is normal ICP?
5-15 mmH2O
What is the worrisome ICP?
> 20 mmH2O
What determines ICP?
- Volume of brain
- Volume of blood
- Volume of CSF
What is the CPP?
Cerebral Perfusion Pressure:
CPP = MAP - ICP
What is Cushing’s reflex?
Physiologic response to increased ICP:
- Hypertension
- Bradycardia
- Decreased RR
What are the 3 general indications to monitor ICP after trauma?
- GCS < 9
- Altered level of consciousness or unconsciousness with multiple system trauma
- Decreased consciousness with focal neurologic exam abnormality
What is Kocher’s point?
Landmark for placement of ICP monitor bolt
What nonoperative techniques are used to decrease ICP?
ICP HEAD: Intubate Calm (sedate) Place drain (ventriculostomy), Paralysis Hyperventilation to PCO2 = 35 Elevate head Adequate blood pressure (CPP > 70) Diuretic (e.g. mannitol)
Can a tight c-collar increase the ICP?
Yes (it blocks venous drainage from brain)
Why is prolonged hyperventilation dangerous?
It may result in severe vasoconstriction and ischemic brain necrosis
What is a Kjellberg?
Decompressive bifrontal craniectomy with removal of frontal bone frozen for possible later replacement
How does cranial nerve examination localize the injury in a comatose patient?
CNs proceed caudally in the brain stem as numbered.
Presence of corneal reflex and gag reflex indicates intact pons and medulla, respectively.
What is acute treatment for seizures after head trauma?
Benzodiazepines
What is seizure prophylaxis after severe head injury?
Phenytoin for 7 days
What is the significance of hyponatremia after head injury?
SIADH must be ruled out
What is an epidural hematoma?
Collection of blood between the skull and dura
What causes an epidural hematoma?
Usually occurs in association with a skull fracture as bone fragments lacerate meningeal arteries
Which artery is associated with epidural hematomas?
Middle meningeal artery
What is the most common sign of an epidural hematoma?
> 50% have ipsilateral blown pupil
What is the classic history with an epidural hematoma?
LOC, followed by a lucid interval, followed by neurologic deterioration
What are the classic CT findings with an epidural hematoma?
Lenticular hematoma
What is the surgical treatment for an epidural hematoma?
Surgical evacuation
What are the indications for surgery with an epidural hematoma?
Any symptomatic epidural hematoma or hematoma > 1 cm
What is a subdural hematoma?
Blood collection under the dura
What causes a subdural hematoma?
Tearing of bridging veins that pass through the space between the cortical surface and the dural venous sinuses or injury to the brain surface with resultant bleeding from cortical vessels
What are the 3 types of subdural hematomas?
- Acute: symptoms within 48 hours
- Subacute: symptoms with 3-14 days
- Chronic: symptoms after 2 weeks or longer
What is the treatment for epidural and subdural hematomas?
Craniotomy with clot evacuation is usually required
What are classic CT findings with a subdural hematoma?
Curved, crescent-shaped hematoma
What is traumatic subarachnoid hemorrhage?
Head trauma resulting in blood below the arachnoid membrane and above the pia
What is the treatment for subarachnoid hemorrhage?
Anticonvulsants and observation
What is a cerebral contusion?
Hemorrhagic contusion of brain parenchyma
What are coup and contrecoup injuries?
Coup: injury at the site of impact
Contrecoup: injury at the site opposite the point of impact
What is DAI?
Diffuse Axonal Injury:
Shear injury to brain parenchyma from rapid deceleration.
What is the best diagnostic test for DAI?
MRI
What can present after blunt trauma with neurological deficits and a normal brain CT?
DAI, carotid artery injury
What is a depressed skull fracture?
Fracture in which one or more fragments of the skull are forced below the inner table of the skull
What are the indications for surgery after a skull fracture?
- Contaminated wound requiring cleaning and debridement
- Severe deformity
- Impingement on cortex
- Open fracture
- CSF leak
What is the treatment for open skull fractures?
- Antibiotics
- Seizure prophylaxis
- Surgical therapy
What are the 2 general types of spinal cord injuries?
- Complete: no motor/sensory function below the level of injury
- Incomplete: residual function below the level of injury
What is spinal shock?
Loss of all reflexes and motor function, hypotension, bradycardia
What does “sacral sparing” mean?
Sparing of sacral nerve level: anal sphincter intact, toe flexion, perianal sensation
What initial studies/interventions are important in spinal cord injuries?
- ABCs
- Maintain BP (IVF, pressers if refractory to fluids)
- NG tube (prevents aspiration)
- Foley
- High-dose steroids
- Complete cervical XRs and those of lower levels as indicated by exam
What are the diagnostic studies for spinal cord injury?
X-rays, CT, MRI
What are the indications for emergent surgery with spinal cord injury?
Unstable vertebral fracture; incomplete injury with extrinsic compression; spinal epidural or subdural hematoma
What is the indication for IV high-dose steroids with spinal cord injury?
Controversial: Blunt spinal cord injury with neurologic deficit (methylprednisolone: high-dose bolus followed by continuous infusion for 23 hours)
Have steroids been proven to help after penetrating spine injury?
No
What is anterior cord syndrome?
Affects corticospinal and lateral spinothalamic tracts; paraplegia; loss of pain and temperature sensation; preserved touch, vibration, and proprioception
What is central cord syndrome?
Preservation of some lower extremity motor and sensory ability with upper extremity weakness
What is Brown-Sequard syndrome?
Hemisection of cord resulting in ipsilateral motor weakness and touch and proprioception loss with contralateral pain and temperature loss
What is posterior cord syndrome?
Injury to posterior spinal cord with loss of proprioception distally
What is a Jefferson’s fracture?
Fracture through C1 arches from axial loading (unstable)
What is a hangman’s fracture?
Fracture through the pedicles of C2 from hyperextension (usually stable)
What is an odontoid fracture?
Fracture of the odontoid process of C2 (view with open-mouth odontoid XR)
What is a Chance fracture?
Transverse vertebral fracture
What is a clay shoveler’s fracture?
Fracture of the spinous process of C7
What is a type I odontoid fracture?
Fracture through tip of dens
What is a type II odontoid fracture?
Fracture through base of dens
What is a type III odontoid fracture?
Fracture through body of C2
What is the incidence of CNS tumors?
1% of all cancers
What is the usual location of primary CNS tumors in adults? children?
Adults: 66% are supratentorial
Children: 66% are infratentorial
What is the differential diagnosis of a ring-enhancing brain lesion?
Metastatic carcinoma, abscess, GBM, lymphoma
What are the adverse effects of tumors on the brain?
- Increased ICP
- Mass effect on cranial nerves
- Invasion of brain parenchyma, disrupting nuclei/tracts
- Seizure foci
- Hemorrhage into or around tumor mass
What are the signs and symptoms of intracranial tumors?
- Neurologic deficit
- Headache
- Seizures
- Vomiting (classically in the morning)
How is the diagnosis of intracranial tumor made?
CT, MRI
What are the surgical indications with intracranial tumors?
- Establishing a tissue diagnosis
- Relief of increased ICP
- Relief of neurologic dysfunction caused by tissue compression
- Attempt to cure in the setting of localized tumor
What are the most common intracranial tumors in adults?
Metastatic neoplasms are most common.
Primary: Glioma (50%) , meningioma (25%)
What are the 3 most common intracranial tumors in children?
- Medulloblastoma (33%)
- Astrocytoma (33%)
- Ependymoma (10%)
What is a glioma?
General name for several tumors of neuroglial origin (e.g. astrocytes, ependymal, oligodendrocytes)
What are the characteristics of low-grade astrocytoma?
Nuclear atypia, high mitotic rate, high signal on T2 weighted images, non-enhancing with contrast on CT
What is the most common primary brain tumor in adults?
Glioblastoma multiforme (GBM)