NEUROSURGERY



NEUROSURGERY

Nervous System

Senses changes in environment, interprets them, stimulates response/movement

□ CNS central nervous system: brain and spinal cord

□ PNS peripheral nervous system: everything else

• Afferent nervous system: sensory neurons take info from PNS to CNS

• Efferent nervous system: motor neurons take info from CNS to PNS

▪ Somatic nervous system: skeletal muscle, conscious control

▪ Autonomic nervous system: cardiac m, smooth m, glands; uncons control

– Sympathetic div = increased skeletal blood flow, decreased organ blood flow ; also called fight or flight

– Parasympathetic div = decr skeletal blood flow, incr organ blood flow

– Both are controlled by hypothalmus and medulla oblongata, go to the same effector or target, are antagonistic

–

Spinal cord transmits info to/from brain, integrates reflexes

□ Begins at foramen magnum and extends to 2nd lumbar; 16-18” in length

□ Vertebrae: 7 cervical, 12 thoracic, 5 lumbar; 5 fused [sacrum], 4 fused [coccyx]

□ Intervertebral disks: separate vertebrae, bear/cushion stress on vertebrae

• Outer layer is tough and called the annulus fibrosis

• Inner core is soft and called the nucleus pulposus

□ Meninges : membranes between vertebrae & spinal cord

• Epidural space between vertebra and dura mater

• Dura mater outermost layer extends to S-2

• Subdural space between dura mater and arachnoid

• Arachnoid mater extends to S-2

• Subarachnoid space contains CSF

• Pia mater adheres directly to spinal cord and extends to L-2

□ Spinal nerves -- 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal

• Names and numbers depend on where enter and exit

• Each has a ventral [motor] and dorsal [sensory] root

Brain: weighs approx 3 lb., protected by the cranium or skull

← Brain stem

□ Medulla oblongata: lowest part, 5 of 12 cranial nerves

• Pyramids: crossing of the spinal nerve impulses

• Reflex centers: hiccupping, sneezing, coughing

• Vital reflex centers:

▪ Cardiac center – heart rate

▪ Vasoconstrictor center - BP via blood vessel diameter control

▪ Respiratory center - breathing

□ Pons: above medulla

• Switching point for motor neurons

• Respiratory center

□ Midbrain or mesencephalon: above pons

• Involuntary eye and head movement in response to auditory stimuli

← Diencephalon

□ Thalamus

• Relay center for sensory information

• Interprets stimuli for example pain from changes in temperature (hot stove); recognizes crude touch NOT localized touch

• 1st level of reasoning occurs here

□ Hypothalamus

• Controls large number of subconscious functions

• Controls most of autonomic nervous system

• Is where endocrine and nervous systems interface

• Homeostasis regulation of the body

• Controls: body temp, thirst, hunger, sleep and waking habits, psychosomatic disorders, rage and aggression

← Cerebellum: 2nd largest part of the brain, primarily a motor area

• Controls skeletal muscles, subconsciously

• Receives sensory input from eyes, muscles, joints, and inner ear

• Posture, balance, coordination, equilibrium

• Muscle sense tells body where other parts are

← Cerebrum: largest part of brain, see p 970, fig 24-4

Motor/sensory/association areas, associated with specific lobes

□ Frontal: memory, abstract thinking, ethics, judgement, emotion, expressive speech, motor

□ Parietal: sensory, receptive speech, written word

□ Temporal: auditory, olfactory

□ Occipital: visual cortex, visual association

Limbic system: controls emotion/functions in cerebral cortex and diencephalon

← Meninges: continuous layer with spinal cord, but NO epidural space

← Cerebrospinal fluid (CSF): shock absorber and circulates nutrients

□ About 800ml/day produced by the choroid plexus, a specialized set of capillaries

□ Circulates in subarachnoid space, central canal [spinal cord], ventricles [brain]

□ Reabsorbed in arachnoid villus found in the parietal lobe

← Blood brain barrier

□ Specialized capillaries exclusive to the CNS, least permeable in the body

□ Advantage = keeps out unwanted chemicals

□ Disadvantage = poor diffusion makes it difficult to treat conditions such as encephalitis

← Cranial nerves: direct from brain, do not go thru spinal cord

□ All originate in the brain stem EXCEPT the 1st and 2nd

□ Classified as sensory or mixed (sensory and motor) nerves

□ Identified by Roman numerals and names

• Olfactory - sense of smell

• Optic – sense of sight/vision

• Occulomotor – movement of eyeball[medial, inferior, superior rectus, inferior oblique], eyelid, pupil, lens [ciliary m]; muscle sense for eyeball

• Trochlear – eyeball movement (superior oblique); muscle sense for eyeball

• Trigeminal

▪ Motor: masseter muscle control

▪ Sensory (convey touch, pain, temp changes)

– ophthalmic (forehead to corner of eye),

– maxillary (corner of eye to upper lip/teeth)

– mandibular (lower lip/teeth/tongue)

• Abducens - eyeball movement (lateral rectus); eyeball muscle sense

FYI: EOM formula LR6(SO4)3

• Facial- facial muscles; lacrimal, salivary glands; anterior 2/3 of tongue (taste)

• Vestibulocochlear - vestibular [balance]; cochlear [hearing]

• Glossopharyngeal -salivary gland secretion and posterior 1/3 of tongue

• Vagus – internal organ control motor and sensory; originates in medulla and goes down through neck into chest and abdomen

• Accessory – head and neck movement, speech, and muscle sense for the head

• Hypoglossal – tongue muscles: swallowing, speech, muscle sense for tongue

Neuropathology

← Cervical spine: can have severe consequences due to all spinal nerves pass thru it. Treatment is conservative, with minimal surgical intervention.

□ Spondylosis: is osteophyte or bone spur formation in the spinal canal

□ Cervical disk extrusion: acute or chronic

← Thoracic spine

□ Spondylosis

□ Extrusion of disk

← Lumbar spine

□ Spondylosis

□ Stenosis

□ Spondylolithesis

□ Disk extrusion

← Neoplasms/Tumors

□ Primary originate in nervous tissue or meninges

□ Secondary are metastasized from other parts of the body

□ Benign tumors: craniopharyngiomas, epidermoids, hemangiomas, menigiomas, acoustic neuromas, pituitary microadenomas; usually excisable via craniotomy

□ Malignant tumors: astrocytes or gliomas; usually cannot be completely removed but efforts are made to remove most

← Head Trauma

□ Scalp lacerations, fractures, hematomas (epidural or subdural), and brain injuries

← Spinal Cord Trauma

□ Vertebral fracture

□ Vertebral dislocation

□ Herniated disk into spinal canal

□ Laceration from GSW or MVA

← Cerebrovascular disease (#3 cause of death in US); symptoms reflect ischemia (TIAs) or hemorrhage

□ Intracranial aneurysm

□ Arteriovenous malformations

□ Brain hemorrhage

□ Stroke or cerebrovascular accident (CVA)

← Congenital Pathology

□ Craniosynotosis: premature closure of the cranial sutures

□ Hydrocephalus: result of obstructed CSF flow

□ Spina bifida

← Infection

□ Abscess

□ Subdural empyema

□ Post-op infection

← Spinal Cord Tumors

□ Intramedullary in the spinal cord

□ Intradural in dura, outside spinal cord

□ Extradural outside spinal cord

← Peripheral nerve pathology

□ Carpal tunnel syndrome - compression of the median nerve

□ Ulnar nerve compression – compression of ulnar nerve by the ligament of Osborne

← Diagnosis

□ History and physical Myelogram

□ Symptoms usually specific to area of pathology CAT Scan

□ Electroencephalogram (EEG) X-ray

□ MRI Cerebral arteriograms

← Medications

□ Lidocaine 1% with epinephrine

□ Topical hemostatic agents: gelfoam, avitene, surgicel, bone wax

□ Antibiotic irrigants

□ Topical papaverine for prevention of spasm during intracranial artery surgery

□ Methyl methacrylate with cranioplasty

□ Heparin saline irrigation again with intracranial artery surgery

□ Contrast solutions with cerebral arteriography

□ Gliadel wafers (tumor bed of glioblastoma)

← Anesthesia : general or could be local with MAC for minor laceration suturing

← Positioning

□ Cranial surgery: supine primarily, with a specialty headrest and or fixation devices, but varies w/ need for access, can be lateral or semi-lateral, sitting, prone

□ Spinal surgery: supine for anterior procedure, prone for posterior

□ Specialty equip: Mayfield headrest, Gardner-Wells tongs

← Preps will require shave esp. on head; surg pref; do not get in eyes/facial orifices

← Draping: towels; adhesive drape; laparotomy, thyroid, craniotomy, lumbar; stockinette for peripheral proc.

← Supplies:

□ Marking pen Hemostatic clips

□ Disposable bi-polar cord Shunt catheters, tubing, connectors

□ Monopolar pencil/bovie Cotton balls

□ Cottonoids/patties Hemovac drain

□ Raney clips Nerve stimulator

□ Telfa Microscope drape

□ C-Arm drape Ultrasound wand drape

← Instruments see p 987-990

□ Minor tray if laminectomy / craniotomy trays do not incl basic instrumentation

□ Laminectomy tray

□ Craniotomy tray

□ Basic ortho tray

□ Plates and screws

□ Specialty self-retaining retractor trays: Greenburg

□ Miscellaneous Instrumentation

← Equipment

□ Operative Ultrasound machine Video tower

□ CUSA Cavitron ultrasonic aspirator Microscope

□ Bipolar and monopolar ECU Stereotaxis system

□ Nitrogen source for power equipment (saws/drills) YAG or CO2 laser

□ Headlight and light source C-Arm and monitor

□ Fluid warming and temperature regulating equipment Cell saver

□ Mayfield overbed table

← Dressings/Drains: surgeon preference

← Post-op care: keep field sterile until patient has left the OR; careful with moving patient to avoid patient injury and hemorrhage

← Post-operative Complications

□ Infection Hemorrhage

□ Nerve damage CSF leakage

□ Meningitis Neurological deficits

← Procedures begin on page 992-1021 in Price

□ Carpal Tunnel Release Craniotomy

□ Hematoma Aneurysm repair

□ Tumor excision Cervical Discectomy

□ Lumbar Discectomy Ventroperitoneal Shunt

(VP Shunt)

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