Neurologic complications of anesthesia


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yA presentation based on the Continuum in Neurology Series

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Neurologic complications of anesthesia

  1. 1. John Michenfelder first coined the term “ Neuroanesthesia”in 1969Almost 167 years after W.T.C. Morton used Ether in the firstsurgical operation
  2. 2. INCLUSIVE OF:1)Adverse effects when drugs are used forsurgery2)Induction of coma in ICUVARIATION OF RISK:1)Surgery performed for Brain disease2)Surgery in Preexistent Neurologic disease3)General or Regional Anesthesia
  3. 3. Major Subdivisions:General AnesthesiaRegional AnesthesiaFurther Subdivisions: In NeurosurgeryIn General SurgeryIn Neurovascular SurgeryIn Pediatric SurgeryIn the ICU
  4. 4. In NeurosurgeryMost common complications:1)Arterial Hypotension2) Reduced Cerebral blood flow3) Cerebral Ischemia from hyperventilation4) Increased Intracranial pressure5) Perioperative Seizures6) Postoperative arterial hypotension
  5. 5. Complication Propofol Inhalational AgentArterial Hypotension + ++Reduced Cerebral blood flow + -Cerebral Ischemia from - ++ #hyperventilationIncreased Intracranial - ++pressurePerioperative Seizures - +(Sevoflurane)Postoperative arterial + +/-hypotension+ = A higher risk of complications- = A lower risk of complications#= This effect is seen in1)Mass lesions with raised ICP2)Effect is dose dependent3)Worse with Isoflurane, Desflurane than Sevoflurane
  6. 6. Propofol is the most preferred in mass lesion withincreased ICPPropofol is a potent antiepilepticLeast interference with intraoperativeelectrophysiological monitoringTime to recovery similar to inhalational agentsRecommendations for Specific situations:Dexmedetomidine in awake craniotomiesMidazolam/Fentanyl for postoperativesedation/analgesiaFentanyl & Remifentanil are also effective
  7. 7. NEWER DRUGS AND APPLICATIONSDEXMEDETOMIDINEa novel sedative Combining optimal doses of a Narcoticanalgesic with an Anaesthetic
  8. 8. IDEAL NEUROANESTHETIC REGIMEN FORCRANIOTOMIES Smooth induction Adequate brain relaxation and control of intracranialpressure Hemodynamic stabilityMaintainence of cerebral perfusion Preservation of cerebral autoregulation Anticonvulsive effect Neuroprotective effectLack of interference with electrophysiologic monitoring Preserved patient coopertion in awake surgeries Rapid emergence and neurological recovery Antiemetic effect
  9. 9. In General SurgeryProblems:1) Delayed Arousal:ElderlyProlonged AnesthesiaPreexistent Brain diseaseComplicated surgeries with Hypotension and Organ failure2) Failure to Arouse:StrokeHypoxic-Ischemic Brain InjuryStatus EpilepticusSepsisMultiorgan dysfunction
  10. 10. 3) Postoperative DeliriumOlder adultsCognitive impairmentPolypharmacyNarcotics/BenzodiazepinesIncidence: 40 to 60%Anesthesia Route/Type: Unclear4) Post Operative Cognitive Dysfunction:Older adultsH/o Postoperative deliriumIncidence: Greater after major Cardiovascular Surgery30 to 60% - First few weeks10 to 60% - 3 to 6 monthsRisk: Alcohol, Old Stroke, Lower educational levelImportant Associations:Worse Long term Cognitive outcomeGreater disabilityIncreased risk of death
  11. 11. Precautions:1)Maintain physiologic homeostasis During andAfter surgery2)Anesthetic Regimen: No evidence3)Depth of Anesthesia: Deeper intraoperative levelof Propofol should be avoided4)Special care in patients with Degenerative Braindisease
  12. 12. Degenerative Brain disease:1. Alzheimer disease:A) Problems with Inhalational agents: IsofluranePossible mechanisms: Increased neuronal calcium dysregulation Increased Amyloid Beta production Increased Tau phosphorylation Activation of Apoptotic pathways
  13. 13. B) Problems with General Anesthetics:Decrease Central AcetylCholine releaseDepress Cholinergic transmissionPrecautions: Using Propofol, Rumifentanil:Less Cholinergic function interference Restricted use of :HypnoticsOpioidsInhalational drugsNeuromuscular blockersReason: Variable response
  14. 14. 2) Parkinson’s Disease:Medication Regimen:Continue medicines close to beginning of AnesthesiaRestart soon Post operativelyIn prolonged surgery: Intraop Levodopa via NGTRisks in PD:Increased rigidity postopPost extubation respiratory failure & Aspiration Pneumonia(From UpperAirway Obstruction)DeliriumAutonomic instability
  15. 15. Anesthetic Agents:Drug Side EffectsSuccinyl Choline Unsafe, Risk of severe HyperkalemiaInhalational drugs Hypotension, ArrhythmiasKetamine Excessive Sympathetic ResponseFentanyl Increased rigidityOpioids Naloxone responsive severe DystoniaThiopental May decrease striatal dopamine releaseNon Depolarizing agents SafePropofol Preferred
  16. 16. Avoid:Antiemetics in recovery room: Droperidol, MetoclopramideMeperidine in those taking Selegiline: Agitation, rigidity, hyperthermiaSpecific Cases: Functional SurgeriesHurdle: Anesthesia should not mask Clinical signsRequirement: Adequate monitoring neededTarget Site of lesion: Thalamotomies, PallidotomiesStimulation: DBS (VIM of thalamus)Drugs:Mild Sedation: DexmedetomidineGeneral Anesthesia: Propofol
  17. 17. Preanaesthetic Parkinson’s check-up :Diagnosis and duration of diseaseAssessment of associated changes in various systemsThe surgical procedure intended (elective or emergency)Antiparkinsonian drugs & potential interactions withanesthetic drugsPreoperative continuation of levodopaPremedication and acid aspiration prophylaxis
  18. 18. 3) Epilepsy:Low risk of perioperative seizures: exception ChildrenProconvulsant:EtomidateIV LidocaineSevofluraneShort acting opioids:AlfentanilSufentanilRemifentanilAnticonvulsant:PropofolBarbituratesBenzodiazepinesIsofluraneDesflurane
  19. 19. 4) Other Neurodegenerative & Neuromuscular:Multiple System Atrophy:Risk : Blood pressure fluctuation (Autonomic dysfunction)General anesthesia Safe with precautionsSpinal : Smoother perioperative course5) Huntington’s Disease:Avoid : Psychotropic medicationsNormal responses to:Muscle relaxantsVolatile AnestheticsBenzodiazepinesOpioids6) ALS:Avoid:Succinyl Choline: Rhabdomyolysis/ HyperkalemiaFor Muscle relaxation: ND blockersSafe Regimen: Propofol & Remifentanil
  20. 20. 7) Myesthenia Gravis:Preoperative Treatment: Plasma exchangePostoperative :Early weaningEarly reinstitution of medicinesShort post op course of high dose IV steroidsAvoid drugs worsening disease:Muscle relaxantsAntibiotics(Quinolones)8) Muscular Dystrophies:Risks:Inhalational Anesthetics: Malignant Hyperthermia(Ryanodine type 1 receptor mutation)Succinyl Choline is contraindicated
  21. 21. In Neurovascular Surgery:Cognitive Dysfunction: ¼ th pts of Carotid Endarterectomy (Day 1 to 1 month post procedure)No relation to regimenDependent on preop Ischemic Brain InjuryStenting V/S Endarterectomy:Increased Cognitive dysfunctionMore Cerebral Micro embolismIn Pediatric Patients:Acclerated Neurodegeneration : Experimental animalmodelsLearning Disability : Early, Repeated anesthetic exposure
  22. 22. In the ICU:Usage:SedationControl of IntraCranial hypertensionRefractory SeizuresProblems:1)Delirium:Avoid prolonged sedation & High dosageDaily sedative interruptionDaily monitoring: CAM for ICUPreferred : Dexmedetomidine V/S Lorazepam/Midazolam2) Propofol Infusion Syndrome:At High doses:>4 to 5 mg/kg/h for >48 hrsPresenting features:Unexplained Metabolic AcidosisRefractory BradycardiaCardiac Failure, RhabdomyolysisLactic Acidosis, LipemiaHyperkalemia, Renal Failure
  23. 23. At Risk: Prolonged high dose infusion in: Refractory Status Epilepticus Refractory Intracranial Hypertension (TBI) To avoid Propofol:Altenatives Adverse effectsHigh dose Midazolam Safe, but Pharmacoresistance developsHigh dose Lorazepam Severe Acidosis (propylene glycol toxicity)Barbiturates(Thiopental/ Hypotension, Myocardialpentobarbital) depression, Hepatotoxicity, Increased infections(Pneumonia)Isoflurane Effective – No Prolonged coma but MRI changes if high dose used>2 weeks (S/o Neurotoxicity)
  24. 24. Regional AnesthesiaAdvantage : Reduced Cardio Pulmonary ComplicationsMechanisms of Neurologic Injury:Mechanical:Direct: Injury from needle/catheterIndirect: HemorrhageStretching/Compression from positioningToxic:Effects of local anesthetics on Neural Structures/MuscleIschemic:When Epinephrine is co administered
  25. 25. Frequent Regional Anesthesia techniquesNeuroaxial Blockade Peripheral Nerve BlockadeSpinal Anesthesia Brachial Plexus block:(Intathecal) Interscalene, Supraclavicular, Axillary, Midhumeral blockEpidural Anesthesia Lumbar plexus block:(Extrathecal) Lumbar Plexus & Femoral nerve block Sacral Plexus block: Sciatic & Popliteal nerve block
  26. 26. Neurological Complications after Regional AnesthesiaNeuropathyCNS toxicity : Seizures, dizziness, perioral numbness,visual& auditory disturbancesTransient pain in buttocks &legsEpidural HematomaEpidural AbscessWorsening/Relapse of Preexistent Neurologic Disease
  27. 27.  Neuropathy is the most common complication.<0.04% - Neuroaxial Block , <3% - Peripheral Block Severe Neurological Complications are rare (<0.4%) Local anesthetics can occasionally produce neurotoxicity Transient Neurologic Symptoms:After Spinal AnesthesiaLocation: Severe bilateral, in buttocks & legsNot explained by structural abnormalityNot influenced by dose/concentration of drugResolve spontaneously in 5 days Epidural Haematoma:Risk:Advanced AgeAnatomic abnormalities of Vertebral ColumnCoagulopathy (Bleeding Diathesis/Anticoagulant effect)
  28. 28. Recommendations of ASRA:1)Stop Warfarin 5 days before2)Reverse Anticoagulation to INR ≤ 1.53)High risk for thromboembolism: Bridging with unfractionated heparin (Stop 4 hrs before surgery) LMWH (Last dose 24 hrs before surgery, Reduce to ½ dose)4)After Surgery: Warfarin resumed on 1st day Heparin: 24hrs: Minor, 48 to 72 hrs :Major surgeries5) If necessary Aspirin may be continued6) Stop Clopidogrel 5 to 10 days before & restart 24 hrs afterprocedure
  29. 29. Perioperative Neuropathies:Suspected Factors:Intraoperative positioning: Mechanical Stress/CompressionProlonged SurgeriesOther predisposing factors:Male sexDiabetesSmokingHypertensionVascular diseaseObesityVery thin Body habitusClinical/Sub Clinical nerve dysfunction
  30. 30. Frequently affected nerves:UlnarSciaticBrachial PlexusLimbo Sacral nerve rootsType:SensorySensorimotorRecovery:Full recovery: days to weeksFew patients have persistent disability