Neurosurgery

Question 1

Most cancers found in the brain are. . .

Answer 1

. . . metastases of distant primaries

The big three are lung, breast, melanoma, and GI.

Question 2

How to distinguish primary brain tumors from metastasized brain tumors

Answer 2

• Primary: Single tumors, occur at various areas in brain
• Metastasized: Multiple tumors, principally at the gray-white junction

Question 3

Red flags for possible brain tumor

Answer 3

• Focal neurologic deficits
• Seizures
• Headache worse in morning
• Cushing’s triad (bradycardia, bradypnea w/ irregular breathing, systolic hypertension)
• Progressive nausea and vomiting
• Bitemporal hemianopia

Question 4

Best imaging test if brain tumor is suspected

Answer 4

MRI w/ contrast

Question 5

Diagnosing brain cancer

Answer 5

• Dx: Start w/ MRI w/ contrast for imaging. Biopsy necessary for definitive diagnosis and pathologic diagnosis.
• Tx: Resection, radiation, and/or chemo. Antiepileptic for seizure prophylaxis. Steroids are a palliative measure.
  
  • Poor prognosis except for meningioma.

Question 6

Only brain tumor with a decent prognosis

Answer 6

Meningioma

Question 7

Calcification of the sella on CT or X-ray always indicates. . .

Answer 7

. . . craniopharyngioma

Question 8

Tumors of the anterior fossa

Answer 8

• Epidemiology: Adults (Anterior, adults)
• Meningioma
  
  • Product of dura, comes in from the side
  • FND induced depends upon area compressed
  • Dx: CT scan alone is sufficient
  • Tx: Resection
• Glioblastoma multiforme
  
  • In the parenchyma, highly malignant
  • Dx: Ring-enhancing lesion or “bat’s wing” deformity
    
    • The only brain cancer that can cross the midline
• Astrocytoma
  
  • In the parenchyma
  • Presents like aboe, but less malignant

Question 9

Tumors of the posterior fossa

Answer 9

• Epidemiology: Pediatric patients (Posterior, pediatrics)
• Medulloblastoma:
  
  • Highly malignant, tends to seed arachnoid space and spread to the spine.
  • Tx: Surgical resection, always add radiation
• Ependymoma:
  
  • Comes from 4th ventricle, obstructive hydrocephalus predominates, does not spread
  • Tx: Surgical resection alone is sufficient
• Both may present w/ obstructive hydrocephalus (progressive N/V and headaches, relieved by assuming fetal position)

Question 10

Schwannoma presentation

Answer 10

N/V, vertigo, hearing loss, tinnitus

Basically. it fucks with CN8.

Bilateral in NF2

Question 11

What causes irregular breathing and hypertension in Cushing’s triad?

Answer 11

• They have slightly different etiologies:
  
  • Irregular breathing is caused by compression of the brainstem. The exact mechanism is poorly understood.
  • Hypertension is caused by increased sympathetic outflow. The CNS can detect poor oxygenation/perfusion and will adjust sympathetic outflow independent of the carotid and aortic arch baroreceptors.

Question 12

Kernohan’s syndrome

Answer 12

A syndrome of uncal herniation characterized by paradoxically, ipsilateral weakness (due to contralateral cerebral peduncle compression).

This is unusual because commonly, an ipsilateral brain lesion results in contralateral motor symptoms. It occurs in patients with increased ICP caused by intracranial hemorrhage or cerebral edema.

Question 13

Brainstem herniation

Answer 13

Question 14

Normal ICP range

Answer 14

5-15 mmHg

Question 15

Monro-Kellie doctrine

Answer 15

V_intracranial = V_Brain + V_CSF + V_Blood

V_intracranial is fixed, and V_Brain is subject to osmotic changes which V_CSF and V_Blood must accomadate.

Question 16

Cerebral perfusion pressure

Answer 16

CPP = MAP - ICP

Question 17

Brain herniation syndromes

Answer 17

Question 18

Tranexamic acid for TBI

Answer 18

• Administered to patients with moderate GCS scores (9-12) within 3 hours of injury
• Prevents development of intracranial hemorrhage due to fibrinolysis and depletion of clotting factors

Question 19

Spinal lesions arising above ___ are likely to produce spinal shock

Answer 19

Spinal lesions arising above T1 are likely to produce spinal shock

This is due to disruption of the sympathetic fibers in this region.

Question 20

“Extra-axial, well-circumscribed, dural-based brain mass that enhances with contrast”

Answer 20

Meningioma desciption

Benign tumors, but may cause compressive symptoms

Resect surgically.

Question 21

Where is the conus medullaris located?

Answer 21

~L1-L2

Hence, below this you get cauda equina

Question 22

In the case of a gunshot wound to the brain, the first test is. . .

Answer 22

CT angio

Question 23

Gunshot wounds to the brain often cause. . .

Answer 23

. . . pseudoaneurysms

These can later break and cause acute hemorrhage, requiring phrophylactic IR coiling/embolization.

Question 24

Brain gunshot wound antibiotics

Answer 24

Vanc, ceftriaxone, flagyl

Question 25

What DON’T you do in the case of brain gutshot wound

Answer 25

Retrieve the schrapnel

Question 26

Jumped facet

Answer 26

• Complications: Spinal shock, diaphragmatic paralysis depending upon level

Question 27

Subarachnoid hemorrhage’s most common nontraumatic etiology

Answer 27

Aneurysm (especially berry aneurysm) rupture