Neurosurgery

1. Neurosurgery

2. Outline • A & P • Pathology • Diagnostics/Pre-operative Testing • Medications/Anesthesia • Positioning/Prepping/Draping • Supplies/Instrumentation/Equipment • Dressings/Drains/Post-op Care • Procedures: Carpal Tunnel Release, Craniotomy, Cervical Discectomy, Lumbar Discectomy, Ventroperitoneal Shunt

3. Nervous System • Functions: • Senses changes in environment • Interprets changes • Stimulates movement to respond to these changes

4. Organization of the Nervous System • Two systems: 1. CNS Central Nervous System • Two major parts: Brain and Spinal Cord 2. PNS Peripheral Nervous System • Everything else

5. Peripheral Nervous System • Two major parts: • Afferent Nervous System • Sensory neurons take info from PNS to CNS • Efferent Nervous System • Motor neurons take info from CNS to PNS

6. Efferent Nervous System • Motor nervous system • 2 parts: • Somatic Nervous System • Skeletal muscle control • Conscious control • Autonomic Nervous System • Cardiac muscle, smooth muscle, and glands • Unconscious control • Has 2 divisions: • Sympathetic Division • Parasympathetic Division

7. Autonomic Nervous System • Sympathetic vs. Parasympathetic • Controlled by hypothalamus and medulla oblongata • Both are different nerves going to the same effector or target • Are antagonistic • Parasympathetic = decreased skeletal blood flow, increased organ blood flow (quietly eating) • Sympathetic = increased skeletal blood flow, decreased organ blood flow (eatus interruptus by a bear!) Also called fight or flight; prepares body for emergencies

8. Spinal Cord • Functions: • Info to and from the brain • Integration of reflexes • Location: • Begins at foramen magnum and extends to 2nd lumbar • About 16-18” in length

9. Spinal Cord Support Structures • Vertebra • 33 total • 7 cervical • 12 thoracic • 5 lumbar • Sacrum formed by 5 fused bones • Coccyx formed by 4 fused bones

11. Intervertebral Disks • Separate vertebrae • Outer layer is tough and called the annulus fibrosis • Inner core is soft and called the nucleus pulposus • Bear stress incurred with body weight and when lifting

12. Spinal Cord Support Structures • Meninges • Between vertebra & 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 extends to S-2 • Subarachnoid space contains CSF • Pia Mater adheres directly to spinal cord and extends to L-2 • Meninges also cover brain/continuous layer/difference epidural space not present

14. Spinal Nerves • 31 pair • Names and numbers depend on where enter and exit • Each has a ventral and dorsal root • Ventral root = motor • Dorsal root = sensory • 8 cervical • 12 thoracic • 5 lumbar • 5 sacral • 1 coccygeal

16. Brain • Protected by the cranium or skull

18. Brain • 4 major parts: • Brain stem • Diencephalon • Cerebellum • Cerebrum Weight about 3 lbs.

20. Support Structures of the Brain 1. Meninges • Continuous layer with spinal cord • NO epidural space

21. Support Structures of the Brain 2. Cerebrospinal fluid (CSF) • About 800ml produced each day by the choroid plexus, a specialized set of capillaries • Circulates inside subarachnoid space through central canal of spinal cord and the ventricles of the brain • Reabsorbed in arachnoid villus found in the parietal lobe • Functions as a shock absorber and circulates nutrients

22. Support Structures of the Brain • Blood Brain Barrier • Specialized set of capillaries exclusive to the central nervous system • Less permeable than any other capillaries in the body • Advantage = keeps out unwanted chemicals • Disadvantage = difficult to diffuse materials out, hence difficulty in treating conditions such as encephalitis

23. Brain Stem • 3 parts: • Medulla oblongata • Pons • Midbrain

24. Medulla oblongata • Contains: • 5 of 12 cranial nerves • Pyramids: function only with motor neurons/a 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

25. Pons • Above medulla • Switching point for motor neurons • Respiratory center

26. Midbrain or Mesencephalon • Above pons • Involuntary eye and head movement in response to auditory stimuli

27. Diencephalon • 2 parts: • Thalmus • Hypothalmus

28. Thalmus • Relay center for sensory information • Interprets stimuli for example pain from changes in temperature (hot stove) • 1st level of reasoning occurs here • Recognizes crude touch NOT localized touch

29. Hypothalmus • Controls large number of subconscious functions • Controls most of Autonomic nervous system • 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

30. 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

31. Cerebrum • Largest part of brain • Motor/sensory/association area • 4 Lobes: frontal, parietal, occipital, temporal • Each controls a specific function be it motor or sensory • Limbic system: controls emotion/functions in cerebral cortex and diencephalon • See page 970 Figure 24-4 in Price

32. Frontal Memory, abstract thinking, ethics, judgement, emotion, expressive speech, motor Parietal Sensory, receptive speech, written word Temporal Auditory, olfactory Occipital Visual cortex Visual association Cerebrum Lobes’ Function

33. Cranial Nerves • All originate in the brain stem EXCEPT the 1st and 2nd • Classified as sensory or mixed (sensory and motor) nerves • Directly off of brain • Do not go through the spine • Identified by Roman numerals and names

34. Cranial Nerves • Olfactory - sense of smell • Optic – sense of sight/vision • Occulomotor – eyeball, eyelid movement (medial, inferior, superior rectus, inferior oblique), pupil constriction, lens accommodation Muscle sense for eyeball • Trochlear – eyeball movement (superior oblique) Muscle sense for eyeball • Trigeminal – masseter muscle control Sensory part has 3 branches: ophthalmic (forehead to corner of eye), maxillary (corner of eye to upper lip/teeth), and mandibular (lower lip/teeth/tongue) All three convey sense of touch, pain and temp changes • Abducens - same as IV eyeball movement (lateral rectus) and eyeball muscle sense FYI: EOM formula LR6(SO4)3

35. Cranial Nerves • Facial- facial muscles, lacrimal and salivary glands anterior 2/3 of tongue (taste) • Vestibulocochlear -last of totally sensory nerves; has 2 branches: vestibular conveys balance and cochlear which conveys sense of 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 – controls head and neck movement, speech, and muscle sense for the head • Hypoglossal – tongue muscles: swallowing, speech, muscle sense for tongue

36. Neuro Pathology

37. Cervical Spine Pathology • Very serious • Can have severe consequences related to all of the spinal cords’ nerve pathways • Spondylosis is osteophyte or bone spur formation in the spinal canal • Cervical disk extrusion acute or chronic • Treatment errs on the side of caution due to potential extreme consequences of surgical intervention

38. Thoracic Pathology • Spondylosis • Extrusion of disk

39. Lumbar Pathology • Spondylosis • Stenosis • Spondylolithesis • Disk extrusion

41. Neoplasms/Tumors • Two types: • Primary • Originate in nervous tissue or meninges • Secondary • Are metastasized from other parts of the body • May be classified as benign or malignant

42. Tumors • Benign tumors: • “Craniopharyngiomas, epidermoids, hemangiomas, menigiomas, acoustic neuromas, and pituitary microadenomas” Price, 2004 • Malignant tumors: • “Astrocytes or gliomas” Price, 2004 • Benign usually excisable via craniotomy • Malignant normally cannot be completely removed but efforts are made to remove most

43. Head Trauma • Includes; • Scalp lacerations, fractures, hematomas (epidural or subdural), and brain injuries

45. Spinal Cord Trauma • Vertebral Fracture • Vertebral Dislocation • Herniated disk into spinal canal • Laceration from GSW or MVA

46. 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)

47. Congenital Pathology • Craniosynotosis “premature closure of the cranial sutures” Price, 2004 • Hydrocephalus result of obstructed CSF flow • Spina bifida

48. Infection • Abscess • Subdural empyema • Post-op infection

49. Spinal Cord Tumors • Intramedullary in the spinal cord • Intradural in dura, outside spinal cord • Extradural outside spinal cord Price, 2004

50. Peripheral Nerve Pathology • Carpal tunnel syndrome - compression of the median nerve • Ulnar nerve compression – compression of ulnar nerve by the ligament of Osborne Price, 2004