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Anaesthesia for pts with neurological conditions - Coggle Diagram
Anaesthesia for pts with neurological conditions
Epilepsy
Definition
Disorder of the brain characterised by a predisposition to generate abnormal asychronous neuronal activity, clinically observed as a seizure
Diagnosis
After 2 seizures with no underlying structural abnormality
After 1 seizure with underlying abnormality
Drug Mx
Valproate and lamotrigine are 1st line for tonic-clonic
Avoid valproate (and carbamazepine?) in women of child bearing age
Carbamazepine & lamotrigine are 1st line for focal
Mechanisms of AEDs
Reuced trasmission @ excitatory synapses
Phenytoin/carbamazepine/valproate/lamotrigine - block presynaptic voltage gated Na+ channels
Topiramate - blocks postsynaptic AMPA and kainate Rs
Levetiracetam - works on presynaptic SV2A R (reduces glutamate release)
Gabapentinoids - Block presynaptic L-type Ca2+ channel
Enhance trasnmission @ inhib synapses
Barbituates - Similar to benzos
Topiramate - Works @ GABA-A R too
Benzos - Enhance GABA action @ postsynaptic GABA-A Rs, increasing Cl- influx
Anaesthetic Mx
Intraoperative
Planning
RA vs GA
Physiological homeostasis
Take AEDs, avoid long starve
Consider timing - morning better to stop AED disruption
In theatre
Caution
Ketamine, etomidate, enflurane, tramadol, meperidine, DA antagonists
Safe drugs
Propofol, benzos, NMBA, volatiles, opioids, analgesics
Postoperative
Minimse AED disruption, alternative routes
Postop seizures
Causes
Epilepsy/eclampsia/shivering/dystonia/syncope
Mx
A-E, ?underlying cause, benzo, status algorithm
Preoperative
Assessment
Current regime/levels/seizure type/other Rx, frequency/driving liscence/social situation/?neuro r/v
Convulsive Status Epilepticus
Definition
Seizure(s) > 5min or 3 in 1h
Ix
Bloods, incl AED levels, toxicology, micro, LP, brain imaging
Complications
Excitotxic CNS injury, hyperthermia, pul oedema, arrhythmia, CVS collapse, AKI, liver inj, rhabdo, trauma, metabolic derrangement
Mx
Fosphenytoin 20mg PE/kg or phenytoin 20mg/kg or levetiracetam 60mg/kg or valproic acid 40mg/kg
Phenobarb 15mg/kg
Supportive + O2, consider thiamine and glucose
GA
Benzo (lorazepam 0.1mg/kg IV)
Parkinson's Disease
Features
Systemic
Tremor, stiffness, impaired balance, mask face
Central
Depression, anxiety, decline in intellectual function
Mouth
Difficulty speaking, excessive salivation, difficulty in swallowing
Lungs
Upper airway obstruction, abnormal ventilatory control
Skin
Increased sweating
Muscle
Weakness, aches
GI
Constipation
General
1% of pts over 65
Loss of dopaminergic neurones in pars compacta of substantia nigra
Multisystem neurological disorder with motor, neuropsychiatric and autonomic features
Treatment
Dopaminergic drugs
Presynaptic
COMT inhibitors (entacapone) increase Ldopa
L-dopa - converted in neurones to dopamine - given with carbidopa to reduce peripheral breakdown
Postsynapic
Dopamine agonists - ripinerole, apomorphine
MAO-B (selegiline) presevre existing dopamine
Deep brain stimulation
Electrical stimulation modifies pathways of basal ganglia and reduces Sx
Electrodes with an IPG
Complications of drug withdrawal
Parkinsonism hyperpyrexia syndrome (PHS)
Rigidity, pyrexia, drop GCS
Due to abrupt withdrawal of L-dopa
Dopamine agonist withdrawal syndrome (DAWS)
Rigidity and psych features and autonomic features
Anaesthetic Mx
Intraoperatively
Planning
Early on list, ensure drugs taken, avoid long starve, RA vs GA, homeostasis
In theatre
Monitoring artefacts, airway, DBS & Diathermy
Caution with
Atropine/halothane/high dose fent/alf, direct acting sympathomimetics (if MAOBs), DA antagonists, serotonin syndrome
Postoperatively
Minimise disruption - apomorphine sc infusion, rotigotine given as transderm patch, consult with PD team
?critical care, analgesic plan, early Mx of complications
Preoperatively
MDT assessment, drug regime, social situation, comorbidities, systems r/v
Dementia
General
AD>vascular>others
Incidence doubles for every 5 yrs
Slow, progressive loss of cognitive ability - exceeding normal age-related decline
Diagnosis
DSM-5
Major neurocognitive disorder
Decline in 1 or more cognitive domain (complex attention, exectutive function, learning & memory, language, perceptual motor function, social cognition)
Interfere with ADLS and not attributal to other mental disorders
Tests
Cognitive testing, blood and urine to r/o other causes, brain imaging, specialist testing in memory clinic
Treatment
Pharmacological
SSRIs (depression)
Citalopram
Risk of serotonin syndrome
Herbal medicines (cognitive impairment)
Gingko biloba
Bleeding risk (due to platelet effect)
NMDA-R antagonists (cognitive decline)
Memantine
Greater SEs of anticholinergics and DA agonists
Antipsychotics (aggression/hallucinations) - block limbic DA Rs and H1 & alpha 2 Rs widely
Risperidone
Vasodilotation and hypotension
Anticholinesterase (cognitive decline)
Donepezil/Rivastigmine
Interacts with NMBAs and reversal agents
Anaesthetic Mx
Intraoperatively
In theatre
Sensitive to anaesthetic agents, avoid benzos, depth monitoring, drug interactions
Postoperatively
Dementia friendly ward environment, delerium Mx, anaglesia planning
Preoperatively
MDT, drug regime, consent/capacity, social situation, high risk pts
Post op delerium
Predisposing Factors
Age, comorbs, frailty, severe illness, dementia, emergency surgery, type of surgery, previous delerium, depression, ETOH, smoking
Modifiable Factors
Intraoperative
Cumulative time with BIS values, variance in BP, hypothemia, high infusion volumes, anaemia, acid base or glucose and electrolyte disturbance
Postoperative
Dehydration, sensory impairment, sleep deprivation, constipation, retention, anaesmia, sepsis, pain, drugs (opiates, benzos)
Mx
Individualised approach - optimise sleep, nutrition, hydration, sensory aids, rationalise medication
Formal assessment tools to assess
Focus on no pharm means first
Single agent, lowest dose, shortest use (haloperidol 0.5mg IV titrated, benzos if ETOH or PD related Sx
Neuromuscular Disease
MS
General
Demyelinating plaques in brain & SC
Weakness, spasticity & sensory dysfunction
Chronic relapsing condition
Sx exacerbated by hypothermia
Acquired, F>M
General
Depending on disease can have effects on smooth or cardiac muscle
Site central (brain/SC), peripheral nerves, NMJ or muscles
Sensitive to NMBs due to extrajunctional ACh Rs
MND
General
Effects UMN & LMNs
Muscle atrophy, fasciculations & weakness
Usually rapidly progressive
Avoid depolarising NMBAs, sensitive to non-depol NMBAs
Acquired
Resp complicatons are common
Charcot-Marie Tooth
General
Spinal & limb deformities (resp compromise due to spinal deformity)
Avoid depolarising NMBA, sensitive to non-depol NMBAs
Chronic peripheral neuromuscular denervation
Document neurology before RA
Hereditary
Friedrich's Ataxia
General
Associated myocardial degeneration (hypertrophic cardiomyopathy)
Skeletal muscle weakness & progressive limb ataxia
Diaphragm involvement can lead to respiratory failure
Avoid depolaring NMBA, sensitive to non-depol NMBA
Autosomal recessive
Caution if CVS/RS involvement
GBS
General
Dx clinical, CSF & neurophysiology
Rx supportive, plasma exchange IVIG
Motor, sensory and autonomic dysfunction
Avoid depolarising NMDA, sensitive to non-depols
Immune mediated polyneuropathy (following infective cause - campylopacter, EBV, CMV)
Anaesthetic considerations
Bulbar dysfunction
GI dysfunction
Autonomic
Neuropathic pain
Respiratory
MG
General
Dx via ice pack test, antibody test, neurophys,tensilon test and thymus imaging
Rx with cholinesterase inhibitors, plasma exchange, immunosuppressants, IVIg, thymectomy
Fatiguable weakness of occular, bulbar and respiratory muscles
Resistant to depolarising NMBA, sensitive to non-depols
Autoimmune, IgG against nACh-R
Myasthenic crisis (lack of ACh action -> weakness)- precipitated by infection, drugs (Mg & aminoglycosides), surgery, pregnancy, change in Rx
Avoid cholinesterase inhibitors -> cholinergic crisis
Lambert-Eaton Myasthenic Syndrome
General
Muscle weakness improves with exercise
Sensitive to depol and non depol NMBAs
Antibodies against presynaptic Ca channels
May have autonomic dysfunction
Immune related, associated with malignancy
Muscular Dystrophy
Duchenne
General
Progressive wasting and weakness of proximal muscles
Cardiac/resp failure leads to death
X inked recessive
Becker
X linked recessive, less severe
Anaesthetics considerations
Avoid depolarising NMBAs, sensitive to non-depols
?TIVA
CVS/RS effects
Myotonic Dystrophy
General
Avoid precipitants of myotonia (hypothermia, shivering, electrical stim)
Avoid depolarising NMBAs and anticholinesterases
Myotonia, muscle wasting, CVS/RS and endo issues
Monitor glucose
Auto dominant with anticipation
Myotonia Congenita
General
Can have palatopharyngeal dysfunction or cardiomyopathy
Avoid depolarising NMBAs, hypothermia, shivering & excessive physical manipulation
Widespread muscle hypertrophy
Autosomal dominant