Neurosurgery overview Flashcards
Preoperative considerations for neurosurgery include
general assessment- access
normal preoperative evaluation- systems, airway, mobility
neurological assessment- LOC, reflexes, motor/sensory function, evaluate for s/s of increased ICP, document preexisting neurological deficits
Describe preoperative considerations for medications & monitoring.
medications- anticonvulsants (frequency & continue), premedications, antibiotics, diuretics, steroids
monitoring- arterial line & intraoperative neuro monitoring
The types of intraoperative neuromonitoring include
MEP
SSEP
EMG
Describe MEP
used in surgeries where motor tract is at risk
direct & scalp electrodes
more sensitive to ischemia than SSEP by 15 minutes and degree detection
difficult to obtain due to pre-existing conditions or anesthetic conditions
Describe SSEP.
most commonly monitored
stimulation of peripheral sensory nerve
mapping in spinal cord and sensory cortex
ischemia detection in cortical tissue
reduce risk of spinal cord/brainstem- mechanical or ischemic insults
-may use paralytic but it does monitor some motor
Describe EMG
records muscle electrical activity needle pairs- continuous recording, triggered responses
uses- detect nerve irritation, nerve mapping, assess nerve function, monitoring cranial nerves
Stereotactic neurosurgery applies rules of
geometry to radiologic images to allow for precise localization within the brain, providing up to 1 mm accuracy
Stereotactic neurosurgery allows surgeons to
perform certain intracranial procedures less invasively
Smaller brain biopsies may be done
under local/MAC
_____ needs to be used for larger brain resections
GETA
With stereotactic neurosurgery, radiologically small markers are affixed to the scalp and forehead with adhesive and it is important that
these fudicials do not move between the time of imaging and entry into the OR
once in the OR the patient’s head is appropriately positioned & the locations of the fudicials are entered into a computer
Medications commonly found in the crani bag include
cleviprex, mannitol, keppra, phenylephrine, precedex, epi
Drips commonly used in craniotomies include
propofol at 40-100 mcg/kg/min ABW- max 40 mg/kg/min for asleep motor mapping and awake craniotomy
phenylephrine at 0.2 mcg/kg/min
remifentanil @ 0.2 mcg/kg/min IBW- no real max if patient needs it due to low propofol dose
Describe common induction medications for craniotomies.
fentanyl, propofol, rocuronium
Antibiotics for craniotomies include
vancomycin & cefazolin
Analgesics for craniotomies include
tylenol
narcotic (hydromorphone or fentanyl)
Antiepileptics for craniotomies include
keppra 1 g & vimpat
Drugs that decrease ICP in the setting of craniotomies include
decadron- 10 mg
mannitol- 50-100 mg (actual dose 0.25-0.5 g/kg)
+/- lasix
Specific drugs used for awake cranies include
caffeine- adenosine receptor antagonist
physostigmine- anticholinesterase
Types of mass lesions include
congenital
neoplastic (benign vs. malignant)
infectious (abscess or cyst)
vascular (hematoma or arteriovenous malformation)
Typical presentation of intracranial mass lesions include
HA (50-60%) seizures (50-80%) focal neurological deficits (10-40%) sensory loss cognitive dysfunction
Supratentorial masses can be found in
frontal: personality changes, increased risk taking, difficulty speaking
parietal: sensory problems
temporal: problems with memory, speech, perception, and language skills
occipital: difficulty recognizing objects, an inability to identify colors, and trouble recognizing words
Infratentorial/Posterior fossa masses can affect
cerebellar dysfunction: ataxia/poor balance, nystagmus, dysarthria, cannot perform rapid alternating movements, loss of muscle coordination
brainstem compression: cranial nerve palsy, altered LOC, abnormal respiration
edema, obstructive at 4th ventricle
Primary tumors include
glial cells- astrocytoma, oligodendroglioma, glioblastoma
ependymal cells- ependymoma
supporting tissues- meningioma, schwannoma, choroidal papilloma