Neurosurgery Flashcards
Name the two structural divisions of the nervous system, and briefly describe each
CNS: brain & spinal cord
PNS: cranial & spinal nerves
Name the eight bones which form the cranium
- Frontal
- Occipital
- Ethmoid
- Sphenoid
- Temporal (x2)
- Parietal (x2)
What is the foramen magnum?
Largest opening in the skull, provides passage for the spinal cord to join the brainstem in the posterior fossa
Name and describe the three meningeal membranes and their relationship to the skull and brain
Dura mater: in direct contact with the cranium
Arachnoid space: a web like space
Pia mater: in direct contact with the surface of the brain
Name the principal lobes of the cerebrum (4)
- Frontal
- Parietal
- Temporal
- Occipital
What three structures comprise the brainstem?
- Midbrain
- pons
- Oblongata
Describe the ventricular system of the brain, and trace the flow of cerebrospinal fluid (CSF) from the sites of production of the sites of absorption
- choroid plexus, lateral ventricles
- foramen of Monroe, 3rd ventricle
- aqueduct of Sylvius
- 4th ventricle
- foramen Magendie/Luschka
- sub arachnoid space brain/spinal cord
- reabsorbed venous sinus blood via arachnoid granulation a
Where (what structure and ventricles) is most CSF formed/produced?
Choroid Plexuses/ Lateral ventricle
Where is most CSF absorbed (site and structures)?
By fingerlike projections of the arachnoid that project into the dural sinuses called arachnoid villi
What is the average volume of CSF in a healthy adult?
125-150mL
What is the average pressure of CSF in a healthy adult?
8-14mmHg millimeters mercury
How many vertebrae are there in the spinal column?
*33* (7 cervical) (12 thoracic) (5 lumbar) (5 sacral) (4 coccygeal)
How many spinal nerves are there in the spinal column?
*31* (8 cervical) (12 thoracic) (5 lumbar) (5 sacral) (1 coccygeal)
At what vertebral level does the spinal cord terminate?
L1-L3; conus medullaris
Briefly describe the caudal equina
downward facing nerves following end of spinal cord
(Lumbar 2-5)
(Sacral 1-5)
(Coccygeal 1)
Name the 5 paraspinal ligaments
- Anterior Longitudinal: runs the length of the column, along the anterior vertebral bodies
- Posterior Longitudinal: runs the length of the column, along the posterior vertebral bodies
- Ligamentum Flavum: binds the laminae of adjacent vertebrae
- Interspinal Ligament: binds the spinous processes of adjacent vertebrae
- Supraspinal Ligament: runs the entire length of the column, along the posterior spinous processes
Name two functional divisions of the nervous system
- somatic (voluntary)
- autonomic (involuntary
what is the subarachnoid space?
CSF filled space between arachnoid mater and pia mater
describe anatomy of an intervertebral disk?
- annulus: fibrous, outer portion
- nucleus pulposus: fluid filled, innermost (jelly donut)
briefly describe the anatomy of a ruptured intervertebral disk
radial fissuring of annulus allowing nucleus pulposus to escape
describe how ruptured intervertebral disk produces symptoms
nucleus pulposus extends into epidural space causing nerve root compression and radiculopathy (pain from pressure/traction on nerve roots)
cranial nerves 1-12
- olfactory
- optic
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- acoustic
- glossopharyngeal
- vagus
- spinal accessory
- hypoglossal
which cranial nerve is responsible for sight?
optic
2nd cranial nerve
which cranial nerve is responsible for sense of balance
acoustic
8th cranial nerve
which three cranial nerves are responsible for motor innervation of the eyes?
(3,4,6)
oculomotor: 3rd
trochlear: 4th
abducens: 6th
which cranial nerve is responsible for sense of smell
olfactory
1st cranial nerve
name the five arteries that form the circle of willis
- Anterior Cerebral
- Middle Cerebral
- Posterior Cerebral
- Anterior Communicating
- Posterior Communicating
what function does the circle of Willis perform?
ensures continuity of circulation in event any of 4 main channels of supply are compromised
name the two arteries (2 anteriorly and 2 posteriorly) that supply the circle of Willis with oxygenated blood?
anterior: internal carotid arteries
posterior: vertebral arteries
name five common sites of the intracranial aneurysm formation/
- anterior communicating art./anterior cerebral art.
- posterior communicating art./internal carotid art.
- origin of anterior cerebral artery from internal carotid
- 1st bifurcation of middle cerebral artery
- origin of basilar artery
anterior fossae
- pituitary tumors
- aneurysms of the circle of Willis
- limited posteriorly by the sphenoid ridge,
middle fossae
- sella turcica, most central part of the middle fosse
- pituitary gland housed in most central portion.
- houses the internal and middle ear structures
posterior fossae
- cerebellum & brainstem
- largest&deepest formed by the
- occipital, sphenoid & petrous portion of temporal bones -
flow of CSF
- lateral ventricles choroid plexuses
- interventricular canal
- 3rd ventricle
- aqueduct of sylvius
- 4th ventricle
- subarachnoid space
- circulates brain, spinal cord
name the three most common surgical approaches to the circle of willis (for treatment of aneurysms) (3)
- frontal
- bifrontal
- pteronial
What is the most frequently the first sign of a ruptured intracranial aneurysm?
-aneurysmal rupture/hemorrhage into subarachnoid space result in extreme splitting headache
Briefly describe Bell’s palsy; what cranial nerve is affected?
- facial 7th cranial nerve*
- lower motor neuron paralysis
- loss of sensation/control of facial muscles
Briefly describe Meniere’s disease; what cranial nerve is affected? (3)
- acoustic 8th cranial nerve*
- causes spontaneous vertigo
- dizziness, sensation of fullness, pressure in ears
Briefly describe trigeminal neuralgia (tic douloureux); what cranial nerve is affected?
- trigeminal 5th cranial nerve
- excruciating, piercing paroxysms of pain of major peripheral divisions
How is tic douloureux surgically treated? (4)
- rhizotomy using glycerol
- balloon/radiofrequency compression
- radiosurgery
- micro-vascular decompression
Briefly describe carpal tunnel syndrome; what nerve is affected?
entrapment of Median nerve on volar surface of wrist
pain, numbness, tingling of fingers, weakness of intrinsic thumb muscle
How is carpal tunnel syndrome surgically treated?
decompression of median nerve achieved by incising transverse carpal ligament
what is a neurectomy?
surgical excision/removal of part or all of a nerve
what is a rhizotomy?
surgical interruption of cranial or spinal nerve root to treat intractable pain or spastic conditions when other less invasive treatments have failed
what is a sympathectomy?
- excision of portion of sympathetic division of autonomous nervous system
- Tx for Hyperhidrosis or Raynauds disease/phenomenon
what is neurolysis?
-freeing or loosening of a nerve from surrounding adhesions to restore nerve function or relieve pain
What is the most frequently encounter neurosurgical problem, which gives rise to pain due to nerve root compression? What is the procedure most commonly performed to treat the condition?
-Intervertebral disc disease; Laminotomy/ Laminectomy
describe a meningocele (Pedi Chapter).
- outside skin*
- failure of union of the vertebral arches during fetal development
- protrusion of the meninges through a gap in the spine due to a congenital defect forming cyst
describe a myelomeningocele (Pedi Chapter).
- inside skin*
- birth defect in which the backbone and spinal canal do not close before birth, meninges protrude forming sac under skin
- Type of spina bifida.
what is cerebrospinal rhinorrhea (Tabers)?
discharge of cerebral spinal fluid from the nose caused by defect or trauma to cribiform plate
what is cerebrospinal otorrhea (Tabers)?
- leakage of cerebrospinal fluid form external auditory canal
- result of prior surgery to ear/mastoid bone or trauma to skull
what is a craniotomy?
- incision into the skull to expose the brain of adjacent structures
- remove lesions
- treatment of arteriovenous malformations
- expose and repair intracranial aneurysms.
- multiple approaches: Frontal, parietal, occipital, temporal or combination
what is a craniectomy?
- permanent removal of section of the cranium
- burrs/rongeurs used to extend burr holes
how does a craniotomy differ from a craniectomy?
- craniectomy: permanent removal
- craniotomy: temporary removal
give some indications/reasons for performing a craniotomy.
- evacuate intracranial hematomas not accessible via burr hole
- control bleeding
- resect/debulk tumors
- excise or clip vascular lesions
- aspirate excess formation
- decompress cranial nerves
give some indications/reasons for performing a craniectomy.
- craniosynostosis treatment
- severe head trauma with increased ICP
- hematoma removal
- tumor removal
- infection of bone
- sub occipital approach grants access posterior fossa
what is a cranioplasty?
-repair of a skull defect resulting from trauma, malformation, or a surgical procedure.
what is a burr hole?
-minimal exposure that can be made to gain access to brain
why might a burr hole be created (be necessary)?
- treatment of chronic hematomas
- removal of localized fluid
- placement of ventricular catheter
- drain obstructed CSF
- measure ICP
- establishment of shunt system
describe the difference between an epidural and a subdural hematoma.
- epidural hematoma: result of blow to head causing tear in middle meningeal artery, on the dura mater under the skull. Rapid deterioration of consciousness
- subdural hematoma: result of venous bleeding, slow forming between dura and arachnoid mater
an epidural hematoma most frequently results from a tear or laceration of what artery?
-middle meningeal artery
what vessels are most commonly responsible for a subdural hemorrhage?
-bridging veins in subdural space
what is a lumbar laminectomy?
removal of one or more vertebral lamina to expose spinal canal
why might a lumbar laminectomy be performed?
-reach spinal canal and adjacent structures to treat compression fracture, dislocation, herniation of nucleus pulposus, cord tumor, spinal cord stimulation
what positions are most frequently utilized for a lumbar laminectomy? Which is most commonly used?
- prone (most common)
- lateral position
what types of frames are commonly used in positioning for a lumbar laminectomy?
- wilson frame (prone)
- wick frame (modified knees to chest)
- andrews Table (modified knees to chest)
what is a Spinal Cord Stimulator unit?
-spinal cord stimulator (SCS) implantable nondestructive medical device used to treat chronic pain intractable pain of trunk and limbs
why might a Spinal Cord Stimulator unit be employed, and how is it used?
-used to treat chronic pain intractable pain by generating electrical impulses to epidural space, producing tingling sensation that masks sensation of pain
what is an arteriovenous malformation (A.V.M.)?
- lesions where direct shunting of arterial blood to venous system occurs
- tightly packed vascular channels increase risk of hemorrhage
how is an A.V.M. treated surgically?
surgical excision of AVM is recommended
name two types of cervical tongs used to employ cervical traction in cases of neck injury (Ortho Ch. Alexander’s).
- gardner wells
- crutchfield
what is the diagnostic x-ray study considered the criterion standard for evaluation of acute head injury? (2)
- CT scan
- differences in tissue density easily detectable
what is methylene blue, and why isn’t it used on the field during neurosurgery?
-causes inflammatory reaction in CNS
-what is myelography? Why might it be used?
-contrast medium is injected into spinal sub-arachnoid space and fluoroscopy is used to view spinal cord, nerve roots and spinal column to demonstrate a defect involving these areas
what is the WADA’s Test? Why might it be used?
-used before brain surgery to lateralize language, memory, and the dominant hemisphere.
describe the condition known as hydrocephalus.
- condition resulting from accumulation of CSF resulting in dilation of ventricular system (produces/circulates CSF)
- can result in spina bifida, tumors, intracranial/intraventricular hemorrhage, aqueductal stenosis
describe the difference between external (communicating) and internal (non-communicating) hydrocephalus.
- communicating: unobstructed flow; problem with reabsorption results in increase ICP
- non-communicating: obstructed flow in ventricular system results in increased ICP
describe the two most frequently employed surgical shunting procedures used to treat hydrocephalus.
- externalized ventralostomy catheter: catheter inserted into right or left lateral ventricle via burr hole; distal catheter externalized and connected to drain to control drainage of CFS and monitor ICP
- internalized VP shunt: one way valve system directs flow of CSF out of ventricular system; controlled and uncontrolled valve systems exists;
give an example of commonly used disposable hemostatic scalp clips. How, why and when are they used?
- raney or Leroy scalp clips
- applied during primary incision; removed during closure
- used as temporary wound pressure for hemostasis
describe the three manners of surgically treating intracranial aneurysms.
- aneurysm clips
- endosaccular occlusion
describe mechanical hemostasis; give several examples of mechanical means of hemostasis.
- hemostatic clips
- bone wax
- ESUs
describe chemical hemostasis; give several examples of chemical means of hemostasis.
- tompical thrombin
- FloSeal
- absorbable gelatin (gelfoam)
- collagen hemostat (avitene, helistat)
- oxidized regenerated cellulose (surgicel)
name and describe the surgical approach for the procedure known as a transsphenoidal hypophysectomy.
- endoscopic transphenoidal approach: Pituitary fossa reached through sphenoidal sinus by transnasal route
- hyphosectomy: complete extracapsular enucleation of pituitary
name the hand-controlled manually-powered driver/instrument (twist-drill) that is used to create burr holes (perforate the skull).
-hudson Brace
name the hi-powered, foot-controlled pneumatic instrument that is used to “turn” bone flaps (during craniotomy) and/or remove laminae (during laminectomy/laminotomy).
-Midas Rex pneumatic drill
name the instrument that is used to remove nucleus pulposus (soft tissue) from the intervertebral disk space during a laminectomy/laminotomy.
-pituitary rongeur
name the instrument that is used to manually remove bone (spurs/osteophytes) from the intervertebral foramina and/or laminae (during laminectomy/laminotomy).
- kerrison Rongeur
- leksell Rongeur
what is the C.U.S.A. (what does it stand for)? Describe its mechanism of action.
- cavitron Ultrasonic Activator
- emits ultrasonic energy field emulsifying abnormal tissue while preserving normal tissue.
- saline emitted from tip emulsifies tissue and CUSA aspirates simultaneously
how/why is the C.U.S.A. utilized in neurosurgery?
-effective for removing abnormal tissue while preserving normal neural tissue
