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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)