Neurosurgery Flashcards
What is Functional Neurosurgery?
-Surgical management of disorders with no gross anatomical target
-Treatment of movement disorders: Parkinson’s, dystonia, essential tremor, epilepsy, OCD
-Ongoing research and treatment of pain, depression, Tourette, headaches, chronic pain, MS
-Goal: provide symptomatic relief, improve quality of life
What is Deep Brain Stimulator Therapy?
-One of the most common Functional Neurosurgeries.
-Placement of electrodes into deep brain structures, connected to pulse generator
-Exact mechanism of action is not fully understood
-Advantages over surgical ablation: nondestructive, reversible, and adjustable.
-Well documented safety and long term benefits.
-Inhibition and/or activation of GABAnergic cells and decrease in production of glutamate
-Parkinsons (need dose of Levodopa on DOS), essential tremor, seizures, dystonias
Describe the Anesthetic Management of Deep Brain Stimulator therapy?
DBS insertion often a 2-part procedure:
1st – awake craniotomy for lead placement
2nd – GETA for electrode and generator placement
Anesthetic goals: suitable surgical conditions, patient safety and comfort
What are Contraindications/Cautions for DBS therapy?
Contraindications: coagulopathy, recent use of antiplatelets, and uncontrolled HTN
Caution with: confusion, extreme anxiety, communication difficulties
Describe the Initial Insertion of a Vagal Nerve Stimulator.
-Indicated for seizures unresponsive to meds
-Electrical stimulation to vagus nerve in neck, electrode tunneled to chest wall generator
-GETA
-Can cause bradycardia when testing device
Describe a Generator Change of a Vagal Nerve Stimulator?
-Can be done under local/sedation
-Similar to pacemaker battery
-Chest wall pocket
Describe anesthetic management of a Spinal Cord Stimulator
Anesthetic technique is surgeon and pt dependent:
-Sedation (heavy MAC)
-GETA
-+/- IONM
-Prone positioning
-May require “wake-up” test to determine proper lead placement
-Often a very challenging anesthetic due to chronic pain and opioid use
-Can be very painful procedure if laminectomy and during tunneling
What is Spinal Cord Stimulation used for?
-Spinal cord stimulation is a pain-relief technique that delivers a low-voltage electrical current to the spinal cord to block the sensation of pain.
-It is widely used and efficient alternative for the management of refractory chronic pain that is unresponsive to conservative therapies
-Mechanism of action originally based on Gate-Control Theory, but as more research is done, it also seems to activate GABA and adenosine receptors
What is a Baclofen Pump used for?
-Baclofen indicated for relief of spasticity r/t to paralysis, CP)
-Lateral position, exposed abdomen and spine
-Allows for access to abdomen and laminectomy site
-Abdominal wall pocket with pump, contains baclofen, tunneled tubing to spine, insertion site in spine at above level of spasticity
-GETA
-Positioning challenge r/t contractures
What are indications for Craniotomy?
-Gliomas - most common, large areas of edema, respond to corticosteroids
-Meningioma – slow glowing, very vascular
-Pituitary adenoma – arise from sella turcica, associated endocrine dysfunction
-35% are secondary neoplasms (breast, lung)
-Slow growing, can be very large before symptoms appear
Describe setup and maintenance of Craniotomy
-Euvolemic, arterial line, 2 large bore IV’s, monitor fluids, ICP if available, avoid fluids with dextrose, Lactated Ringers, T&C,
-Blood sugar monitoring, ABG’s
-2 large bore IV’s with extensions if arms tucked (careful of kinking) one IV with blood tubing
-Adequate relaxation and anesthesia
-Intra operative neuro monitoring?
-Arterial line
-Decadron (none for TBI)
-Antibiotics
-Anti-convulsant, mannitol available
-Extension for circuit, IV’s, BIS monitor, Precordial stethoscope, Esophageal
-Bair hugger, fluid warmer
-Drips available if needed, propofol, neo, +/- esmolol, have lebatolol
-Propofol ready for PINS, or if tunnel procedure, have in line ready to go
-Full Reversal, smooth wake up, prevent bucking (lidocaine)
-Intubated to ICU? Monitors, Report
Describe Management of Pituitary Surgery?
-Evaluate pt for hormone hypersecretion
-Steroids (hydrocortisone) typically given intra-op
-Transphenoidal or endoscopic nasal approach more commonly used than intracranial approach, bed may be 90 degrees or 180
-GETA , sitting or semi-fowlers position (caution with VAE)
-Tumor may grow around optic nerve, internal carotid artery, or cavernous sinus – be prepared for blood loss
-Monitor for post-op DI, SIADH
-Tx for DI – DDAVP, vasopressin gtt, fluid restriction
-Pt may suffer from acromegaly or cushing’s syndrome. Airway, cardiac concerns
-Visual Disturbances
Describe Transsphenoidal Tumor Resection.
-Endoscopic approach decreases trauma, minimizes blood loss, allows for direct assessment to pituitary, decreased incidence of DI and hypopituitarism.
-Less invasive and pt often go home POD 3
Anesthetic goals: optimize cerebral oxygenation, maintain hemodynamic stability, provide ideal surgical field (minimal EBL), and smooth emergence
Describe Posterior Fossa Surgery
Posterior Fossa holds vital structures.
-Cerebellum, mid pons, medulla
-GETA
-TIVA v ½ MAC, PIV x 2 or central line, Aline, IONM
-Positioning challenges – prone, lateral, sitting
What are risks associated with the Sitting Position?
VAE, pneumocephalus, quadriplegia from severe neck flexion, spinal cord compression, increase cerebral venous congestion
Describe monitoring and treatment of Venous Air Embolism?
Prevention – decrease gradient between heart and surgical field, normo- to slight hypervolemia,
Monitoring – Precordial doppler (standard) – Right side, 4th intercostal space, TEE – most sensitive monitor, abrupt decrease in EtCo2, HOTN
Treatment – Notify surgeon to flood field, 100% FiO2, lower HOB, CVC aspiration, cardiopulmonary support if needed
What are complications associated with Posterior Fossa Surgery?
-Arrhythmias are common with brainstem manipulation
-Bradycardia most frequent - usually subsides with cessation of stimulus
-Tell surgeon you have bradycardia
-Severe HTN
-Hemodynamic control is essential
-May have extreme PONV – consider postop intubation
-Delayed emergence – consider brainstem, cranial nerve injuries
-May elect to delay emergence 2o airway edema, airway protection, brainstem manipulation, N/V
-Pre-Extubation Criteria – LOC, airway and/or gag reflexes, airway swelling, respiratory pattern
Consider deep extubation for hemodynamic stability, cerebral pressures
What is Craniosynostosis?
Premature closure of cranial sutures
-Can be associated with other syndromes
-May present with airway challenge
-If severe deformity – manage ICP, protect airway
-Based on severity, can be done open or endoscopic
-Elective surgical management (done 6 mo – 2 yrs old): correct the skull deformity, prevent progression, reduce risk of raised ICP
-Have blood in Room, large IV’s
Describe anesthetic management of Craniosynostosis.
Traditional open procedures are VERY bloody, child can exsanguinate rapidly.
-Have blood in Room, large IV’s or central line, art line
-Standard GETA
-Start PRBC transfusion once incision made, be prepared with FFP, plts, cryo on hand if needed
-Careful with fluid overload
-Consider TXA bolus and infusion
-Monitor for VAE
List the normal timeline of Fontanelle closure.
Anterior Fontanelle- 18 months
Posterior Fontanelle- 2 months
Anterior Lateral- 2 months
Posterior Lateral- 2 years
Describe anesthetic management of Traumatic Brain Injury
-Check for other injuries: Facial fractures, C-spine instability
-Art line, large bore IV’s
-Hemodynamic control: keep CPP
-T&C with blood available
-Pressors set up and ready to go
-ICP management
-HOB, mannitol, Lasix in room
-Shearing injury (When you hit head, brain goes back and rubs on cranial bones, and then comes forward again)
-NO STEROIDS WITH TBI!!!
-Tight glucose control: vulnerable to hypoglycemia
What is pre-anesthetic evaluation of a TBI?
Important for baseline neuro exam:
-Nausea, vomiting
-Altered mental status
-Pupillary size and reactivity
-Seizures
-Visual disturbances, photophobia
-Headaches
-Extremity numbness, tingling, weakness
-Airway
-Glasgow
Labs:
-CBC
-BMP
-Coags
Diagnostics:
-EKG
-Echo
-CT
-MRI
Blood available ?
Describe different positioning concerns with neurosurgery?
Mayfield or Garner-Wells tongs (Pins):
-Can be very stimulating
-Ensure adequate anesthetic depth (caution with agent bolus – IONM changes)
Sitting:
-Air embolism
-Oral RAE ETT (away from surgical field)
Prone:
-Pressure points
-Post-op visual disturbances, airway swelling
Lateral:
-Pressure points
Describe Anesthesia Maintenance for Neurosurgery?
-TIVA or volatile at ½ MAC+ TIVA (Propofol, dexmedetomidine, narcotics, inhalation agent)
-Ensure all IVs working, bed may be turned and arms tucked
-A-line transducing
-Close monitoring of potential position injuries
-Maintain acceptable BP, CO2 levels (consider hyperventilation)
-Control of ICP is critical (ICP control – head up, ETT tape not too tight, BP acceptable, CSF drain functioning, enough anesthetic agent?)
-Anticonvulsants- If seizure— 20mg propofol, tell surgeon immediately-cold saline on brain
-Normothermia
-Monitor labs (Na, glucose, osmolarity) especially for signs of DI (alterations in ADH, need for vasopressin, stress response ↑cortisol
-Fluid management (IVF – LR, plamalyte, NS; avoid glucose containing solutions. May need mannitol or hypertonic saline to control edema)
-Vasoactive agents
What is Central Neurogenic DI?
-Diuresis (16% 5-10 days after injury)
-Hypernatremia, hypovolemia, Polyuria- decrease in ADH
Causes: damage to post pituitary
Treatment- DDAVP (synthetic hormone similar to ADH)
What is Syndrome of Inappropriate Anti-diuretic hormone (SIADH)?
(33% after TBI)
-Renal absorption of water, concentrated urine, hyponatremia, hypervolemia*
-Disruption of pituitary/hypothalamus
-SIADH- Volume expansion
What is Cerebral Salt Wasting Syndrome?
-Lose Na and ECF, increased levels of ADH
-Dehydration, hypotension, hyponatremia
-CSWS-Volume depletion
Describe initial management of Acute Spinal Injury Stabilization?
-May have undiagnosed secondary injury: Facial, brain, thoracic, abdominal, pelvic
Respiratory status:
-Intubation → awake FOI, video scope, in-line stabilization
-Succinylcholine OK 1st 24 hrs-3days then avoid due to Upregulation of Ach receptor sites and can cause hyperkalemia
Hemodynamic support
What is Spinal Shock?
Impaired spinal autoregulation.
-Skin is pink, vasodilated, cool and clammy
-Sensory-motor deficits and flaccid paralysis below level of injury usually lasting up to 6 weeks followed by spasticity
-Autonomic impairment, hypovolemia
-Ensure proper fluid balance (crystalloid, colloid, product)
-Respiratory status-C3,C4,C5-keep the diaphragm alive. VC may have dropped. In line stabilization for intubation
-Cardiac accelerators T1-4. If these are effected, will have unopposed vagal tone (bradycardia)
What is Autonomic Hyperreflexia?
Pain below the level of injury is attenuated by descending inhibitory tracts. However, after spinal cord injury, these inhibitory tracts are not able to get through.
-Profound sympathetic responses to stimulus below level of injury are unopposed.
Lesions at what level are likely to develop Autonomic Hyperreflexia?
85% are Lesions above T6 (the higher the lesion the higher the probability) Can be at T7 and above. Even high thoracic transections are vulnerable.
What are symptoms of Autonomic Hyperreflexia above the level of injury?
Compensatory above-Nasal stuffiness, headache, pulmonary edema, bradycardia, vasodilation
What are symptoms of Autonomic Hyperreflexia below the level of injury?
Vasoconstriction.
-HTN, vasoconstriction, bradycardia, arrhythmias
What is the Anesthetic Management of Autonomic Hyperreflexia?
-Minimize triggers-cutaneous, visceral pain, full bladder, kinked catheter etc
-GETA or spinal anesthesia for procedures
-Use of vasodilators- Have Nipride on hand
Describe anesthetic management of ACDF?
-Anterior stabilization of cervical spine with removal of disc
-Retractor can compress airway = edema, high PIPs, coughing
-Need for cervical stability during DL – FOI or glidescope
-NIMS ETT to monitor nerves – no paralytics or LTA
-Surgeon may position in extreme extension – monitor ETT placement
-PIV x 2, ± Aline (not typically)
-Maintain MAPs > 85 mmHg for cord perfusion
-Arms tucked
-Intra-operative nerve monitoring
-Posterior approach the patient will be in PINS
Describe Anesthetic Management of Anterior Posterior Cervical Fusion (APCF)
-Same anesthetic management as PCF
-Consider post-op intubation due to potential for airway swelling and difficult re-intubation
-Typically surgeon does anterior portion then posterior
-Surgeon will position head
-Head pins typically used
Describe anesthetic management of Scoliosis Surgery?
-Very long, bloody case.
-GETA with IONM. TIVA (?)
-2 large PIV or central line
-Aline
-Prone position for long surgery (careful with pressure points, eyes)
-Blood products available
-Pain control methods
-Busy surgery for both surgeon and anesthesia
-Commonly seen during early summer months in pre-teen – teenagers
Describe Anesthetic Management of
Spinal Stabilization
Positioning concerns:
-Prone, lateral, extreme lateral
Post-op vision loss (prone):
-Decrease Blood pressure, pressure to eye, fluid overload
-Techniques to accommodate IONM
-Potential for excessive EBL and need for transfusion
-Post-op extubation +/ (Facial, airway swelling, deflate cuff and check for leak)
-Pain control: Multi-modal, opioid sparing
