Surgical Technology for the Surgical Technologist: Neurosurgery Study Guide

Clinical Application: Emergency Neurosurgery Case Study

• Patient Profile: A $10$-year-old female admitted to the Emergency Department ($ED$) following a fall from a slide at a playground, resulting in head trauma to the right side.
• Injury Progression:
  • Initial State: Immediate Loss of Consciousness ($LOC$) at the scene.
  • Lucid Interval: Regained consciousness upon arrival at the $ED$; patient was able to follow verbal commands.
  • Reported Symptoms: Nausea and left-sided headache.
  • Physical Findings: Hemiparesis (weakness on one side of the body).
• Clinical Deterioration:
  • Patient lost consciousness again during the neurosurgical examination.
  • Signs of increased Intracranial Pressure ($ICP$): Hypotension (low blood pressure) and Bradycardia (low heart rate).
  • Ocular Sign: The left pupil is now fixed and dilated.
• Surgical Consultation: An emergency surgical procedure was ordered immediately.
• Critical Analysis Questions:
  • What is the probable diagnosis?
  • Why was an emergency procedure prioritized?
  • Which surgical intervention will be performed?
  • What is the long-term prognosis for the patient?

Chapter $24$ Learning Objectives

• Identify the anatomy and physiology of the nervous system.
• Summarize the pathologies requiring neurosurgical intervention and their associated terminology.
• Identify types of procedures and specific preoperative diagnostic neurological tests.
• Describe the names and applications of neurosurgical instruments, supplies, and medications.
• Demonstrate the names and uses of specialized neurosurgical equipment.
• Determine the intraoperative preparation of the patient undergoing neurosurgical procedures.
• Outline the standard surgical steps for neurosurgical procedures.
• Interpret the purpose and expected outcomes of neurosurgical procedures.
• Identify immediate postoperative care and potential complications of neurosurgical procedures.
• Evaluate specific changes related to preoperative, intraoperative, and postoperative neurosurgical care.

Glossary of Key Terminology

• Abscess: A localized collection of pus in the brain or surrounding tissues.
• Acute: A condition of sudden onset and high severity.
• Cerebellum: The back part of the brain that coordinates muscular activity.
• Cerebrum: The largest part of the brain, responsible for voluntary muscle activity, vision, speech, taste, hearing, thought, and memory.
• Circle of Willis: A ring-shaped vascular structure at the base of the brain providing collateral circulation.
• CNS (Central Nervous System): Consists of the brain and spinal cord.
• Craniosynostosis: Premature closure of the cranial sutures in an infant.
• Decompress: To relieve pressure on the brain or spinal nerves.
• Epidural Hematoma: Accumulation of blood between the skull and the dura mater.
• Extruded: Material (like a disc) forced out of its normal position.
• Glioma: A tumor arising from glial cells.
• Intracranial Pressure (ICP): Pressure exerted by fluids such as Cerebrospinal Fluid ($CSF$) inside the skull.
• Meninges: The three membranes (dura mater, arachnoid, and pia mater) that envelope the brain and spinal cord.
• Osteophyte: A bony outgrowth or bone spur.
• PNS (Peripheral Nervous System): The network of nerves outside the central nervous system.
• Transsphenoidal: Reaching the pituitary gland through the sphenoid sinus.

Specialized Equipment and Instrumentation

• Cranial Instrument Sets:
  • Minor Set: Contains basic surgical instruments.
  • Basic Craniotomy/Neurosurgery Set: Includes Hudson Manual Drill with specialized tips and attachments; Gigli Saw with handles and guides for bone flaps; Bone Rongeurs (Love-Kerrison, Leeksell, Stille-Luer, Adson, Ferris-Smith).
  • Specialized Dissectors: Penfield dissectors (Numbers $1$ through $5$) used for bone and tissue separation.
  • Retractors: Self-retaining types (Gelpi, Weitlaner, Adson, Beckman-Adson cerebellar); Brain retractors (Greenberg, Leyla, or Sargile system).
• High-Power Systems and Visualization:
  • Power Drills: Midas Rex or Anspach pneumatic/electric systems with various burrs and drill bits.
  • Micro-Surgical Tools: Arachnoid knives, Micro-forceps (bayonet shaped), Jacubson micro-vascular needle holders, Rhoton micro-forceps.
  • Surgical Microscope: High-resolution with variable magnification.
• Positioning and Fixation Devices:
  • Gardner-Wells or Mayfield Pins: Used for stable head fixation during craniotomy.
  • Mayfield Horseshoe Headrest: Used for cervical spine surgery.
  • Wilson Frame or Andrews Table: Used for prone positioning during thoracic or lumbar spinal surgery.
• Specialty Equipment:
  • CUSA (Cavitron Ultrasonic Aspirator): Emulsifies abnormal tissue using ultrasonic energy while sparing healthy neurons; utilizes saline irrigation and suction.
  • Lasers: $Nd:YAG$ for coagulation of hemorrhagic vessels; $CO_2$ for precise tissue removal in difficult-to-access areas.
  • Neuro-Endoscopy: Includes light source, camera, monitor, and flexible/rigid endoscopes.
  • Stereotactic Systems: Precise target navigation in the brain using $CT$ or $MRI$ coordinates.

Overview of Neuroanatomy

• The Skull/Cranium: Composed of $8$ primary bones:
  • Frontal ($1$): Forehead and roofs of orbits.
  • Parietal ($2$): Sides and roof of cranium.
  • Temporal ($2$): Lower sides and base.
  • Sphenoid ($1$): Base of the cranium, floor and sides of orbits.
  • Occipital ($1$): Back and large portion of the floor.
  • Ethmoid ($1$): Floor of cranium and nasal cavity walls.
• The Meninges:
  • Dura Mater: Outermost, thick, fibrous connective tissue.
  • Arachnoid Mater: Middle, serous membrane.
  • Pia Mater: Innermost, vascular membrane nourishing the neural tissue.
  • Subarachnoid Space: Located between arachnoid and pia; contains $CSF$.
• Brain Structure:
  • Cerebrum: Divided into lobes (Frontal, Parietal, Temporal, Occipital). Surface contains convolutions (gyri), shallow depressions (sulci), and deep grooves (fissures).
  • Cerebellum: Coordinates complex movements; located posterior to the medulla.
  • Brain Stem: Midbrain, Pons, and Medulla Oblongata; regulates respiratory and cardiac functions.
• Blood Supply: Provided by a system of arteries branching from the Circle of Willis.
• Intracranial Neoplasms (Table $24-2$):
  • Glioma: Accounts for $40\%$ of primary brain tumors; mostly malignant.
  • Astrocytoma (Grades I & II): Long-term symptom presentation.
  • Astrocytoma (Grades III & IV): Malignant glioblastomas, survival often less than $12$ months.
  • Meningioma: Benign tumors arising from meninges; recur if not fully excised.

Surgical Procedure: Craniotomy ($24-1$)

• Indications: Treatment of tumors (benign like craniopharyngioma or malignant like glioma), hematomas (epidural/subdural), brain abscesses, or trauma-induced hemorrhage.
• Positioning: Supine is most common for frontal, parietal, and temporal lobe access. Lateral or semi-lateral used for posterior fossa, brainstem, or cerebellum access. Sitting or prone may be used for occipital lobe or cerebellum.
• Intraoperative Steps:
  • Incision: Marking the site; injecting $1\%$ Lidocaine with Epinephrine for hemostasis. A $U$-shaped incision is typical.
  • Scalp Hemostasis: Raney scalp clips or Dandy clamps are applied quickly to manage severe scalp bleeding.
  • Exposing the Skull: Galea and periosteum are incised via electro-surgery.
  • Burr Holes: One or more holes created using a pneumatic drill (Midas Rex) or manual Hudson brace. Saline irrigation is used to prevent bone dust friction and heat.
  • Bone Flap: A craniotome with a dura guard or a Gigli saw is used to connect the burr holes. Bone flaps are stored in antibiotic-saline solution (labeled).
  • Dura Management: The dura is separated from the skull using a Penfield Number $3$ dissector. High-tensile silk or nylon ($4-0$) traction sutures are used.
  • Closing: Titanium plates and screws or stainless steel wire fix the bone flap back to the skull. A Hemovac drain may be placed.
• Technologist Note: Ensure warm saline ($10\,ml$ syringe) is available to clear blocked Frazier suction tips. Never use Bacitracin on brain tissue as it may cause seizures.

Surgical Procedure: Aneurysm Repair ($24-2$)

• Etiology: Ballooning of arterial walls, typically at bifurcations in the Circle of Willis ($85\%$ in the carotid system).
• Diagnosis: High-resolution $MRI$ or selective cerebral angiography.
• Surgical Goal: Isolation of the aneurysm from the parent vessel using a specialized aneurysm clip.
• Pathology Risks: Rupture leads to severe hemorrhage, meningeal irritation, and focal brain injury.
• Instruments/Supplies: Micro-surgery set, various aneurysm clips (temporary and permanent), and Papverine to prevent vasospasms.
• Postoperative Outcome: Accurate clipping yields good to excellent long-term prognosis.

Surgical Procedure: Spinal Surgery ($24-9$)

• Anatomy: The spinal column consists of $33$ vertebrae: $7$ cervical, $12$ thoracic, $5$ lumbar, $5$ sacral (fused), and $4$ coccygeal (fused). Each vertebra contains a vertebral body, lamina, pedicle, and transverse processes.
• Lumbar Laminectomy for Discectomy:
  • Purpose: Removal of a herniated/extruded disc (nucleus pulposus) to relieve pressure on the nerve roots.
  • Common Levels: Majority occur at $L_4 - L_5$ or $L_5 - S_1$.
  • Spinal Fixation: If laminectomy destabilizes the spine, fusion using bone grafts (from iliac crest) and hardware (rods, cages, screws) is performed.
  • Instrumentation: Meyerding or Taylor manual retractors; Adson-Beckman self-retaining retractors.
• ACDF (Anterior Cervical Discectomy and Fusion):
  • Cloward Technique: Uses a specific drill/cutter. The graft is usually taken $1\,mm$ thicker than the drill size to ensure stability via muscle tension. C-spine $X$-rays used horizontally for level identification.
• Technologist Note: Disc material resembles crab meat. Always receive and verify samples with the surgeon of any tissue excised.

Neuro-Interventional Procedures

• VP Shunt (Ventriculoperitoneal Shunt):
  • Goal: Treat hydrocephalus (excessive $CSF$ production or blockage) by diverting fluid from ventricles to the peritoneum.
  • Components: Ventricular catheter, reservoir, and distal peritoneal catheter. Tunneler used for subcutaneous passage.
• Ventriculoscopy:
  • Indications: Treatment of hydrocephalus without a permanent shunt (ventriculostomy of the $3^{rd}$ ventricle floor).
  • Specific Requirement: Fluid irrigation must be strictly controlled at a very low rate ($15\,ml/min$) using body-temperature Ringer’s Solution.
• Transsphenoidal Hypophysectomy:
  • Approach: Accessing the pituitary gland via a nasal (septal) or sublabial (gum line) incision. The sphenoid sinus provides direct entry into the Sella Turcica.
  • Grafting: Fascia grafts from the patient's thigh may be used to prevent $CSF$ leaks.
• Rhizotomy:
  • Indication: Chronic pain or spasticity (common in children with Cerebral Palsy). Involves selective severing of sensory nerve roots ($L_2$ to $S_2$) based on Electromyography ($EMG$) patterns.