Anaesthesia for a patient with parkinsonism disease for non neurological surgery . With possible viva questions and answers exam ready answer for md anaesthesia exam theory.

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Anaesthesia for Parkinson's Disease Patient Undergoing Non-Neurological Surgery

Introduction

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by degeneration of dopaminergic neurons in the substantia nigra pars compacta, leading to dopamine depletion in the nigrostriatal pathway and relative cholinergic excess. Classic features: bradykinesia, rigidity, resting tremor, postural instability (TRAP). With increasing age of surgical patients, PD patients are frequently encountered for non-neurological surgery (hip fracture, cataract, GI, urological procedures). Anaesthetic challenges arise from disease-related autonomic and bulbar dysfunction, chronic drug therapy with narrow therapeutic windows, and drug interactions with anaesthetic agents.

Preoperative Assessment

History

Duration and stage of disease (Hoehn and Yahr staging)
Current drug regimen - levodopa/carbidopa dose and timing (critical - note exact dosing schedule)
Presence of "on-off" phenomena, dyskinesias, wearing-off effect
Associated autonomic dysfunction: orthostatic hypotension, constipation, urinary retention, sialorrhea
Bulbar symptoms: dysphagia, aspiration risk, poor cough reflex, weak voice
Respiratory: restrictive pattern from chest wall rigidity, upper airway obstruction
Cognitive status/dementia (occurs in up to 30-40% with advanced disease), depression, psychosis
Deep brain stimulator (DBS) in situ - device details if present

Examination

Severity of tremor, rigidity, postural instability
Orthostatic BP measurement (supine and standing)
Airway assessment - rigidity can affect mouth opening/neck movement to a lesser degree, but bulbar dysfunction is the main airway concern
Assess swallowing/aspiration risk

Investigations

Routine - ECG, electrolytes, renal function
Pulmonary function tests if significant restrictive disease/aspiration history
Nutritional status (dysphagia can cause malnutrition)

Key Anaesthetic Principle: Never Stop Levodopa Abruptly

Levodopa has a very short plasma half-life (60-90 minutes)
Abrupt withdrawal (even one missed dose) can precipitate acute akinesia, severe rigidity, dysphagia with aspiration risk, and rarely a Parkinsonism-hyperpyrexia syndrome resembling neuroleptic malignant syndrome (muscle rigidity, hyperthermia, autonomic instability, rhabdomyolysis)
Continue anti-parkinsonian medication up to and including the morning of surgery, and resume as soon as possible postoperatively (via NG tube or rectal/transdermal rotigotine patch if oral intake delayed)
If prolonged NPO expected, consider perioperative rotigotine patch or apomorphine infusion (in consultation with neurology) as bridging therapy

Drug Interactions - What to Avoid

Drug/Class	Problem	Reason
Metoclopramide, prochlorperazine, droperidol	Worsens Parkinsonism	Central dopamine (D2) receptor antagonists
Typical antipsychotics (haloperidol, chlorpromazine)	Worsens rigidity, precipitates NMS-like crisis	D2 antagonism
Butyrophenones	Same as above	Same
Ketamine	Theoretical exaggerated sympathetic response, hallucinations	Sympathomimetic and psychotomimetic effects, use cautiously
Pethidine (meperidine)	Avoid with MAO-B inhibitors (selegiline, rasagiline)	Risk of serotonin syndrome
Suxamethonium	Traditionally cautioned - exaggerated hyperkalemic response described in PD with severe muscle rigidity/immobility, though evidence is weak; safe in most cases	Denervation-like state in severe disease
Halothane (largely obsolete now)	Arrhythmias with levodopa-induced catecholamine sensitization	Myocardial sensitization

Safe for antiemesis: ondansetron, domperidone (does not cross BBB significantly), or low-dose dexamethasone.

Anaesthetic Technique

No single technique is contraindicated - choice is guided by the surgery, patient's autonomic/bulbar status, and ability to lie still/cooperate.

Regional/Neuraxial Anaesthesia

Preferred where feasible (peripheral, lower abdominal, orthopaedic surgery) - avoids airway manipulation and polypharmacy interactions, allows continued oral medication
Caution: tremor may make patient positioning and cooperation for block placement difficult
Autonomic dysfunction increases risk of exaggerated hypotension with neuraxial sympathetic blockade - use cautious incremental dosing, have vasopressors ready
Patient may not tolerate lying still for long procedures due to rigidity/tremor/dyskinesia - consider light sedation

General Anaesthesia

Often necessary for major surgery, or if patient cannot lie still, or has severe dyskinesias/tremor
Induction: Propofol is preferred; it has been reported to acutely (transiently) suppress dyskinesias but does not worsen Parkinsonism. Etomidate can be used in cardiovascular instability. Avoid ketamine as sole agent if possible.
Airway: high aspiration risk due to bulbar dysfunction - consider rapid sequence induction if significant dysphagia/reflux; secure airway with cuffed ETT for longer procedures
Muscle relaxants: Non-depolarizing agents are safe. Succinylcholine can be used if no severe fixed rigidity/disuse (theoretical hyperkalemia risk in severe immobile disease)
Maintenance: Volatile agents (sevoflurane, isoflurane) or TIVA with propofol - both acceptable. Avoid unnecessary deep anaesthesia in the elderly with cognitive impairment (risk of postoperative delirium/POCD)
Avoid droperidol, metoclopramide, prochlorperazine for PONV prophylaxis
Temperature and glucose monitoring - autonomic dysfunction impairs thermoregulation

Monitoring

Standard ASA monitoring
Continuous BP monitoring (invasive if major surgery or significant autonomic dysfunction) - watch for orthostatic/intraoperative hypotension
Temperature monitoring - impaired thermoregulation, risk of both hypothermia and (rare) hyperthermic crisis if medications missed
Depth of anaesthesia monitoring (BIS) useful given sensitivity to cognitive effects and drug interactions in elderly PD patients
Neuromuscular monitoring if relaxants used, given baseline rigidity may confound clinical assessment of recovery

Intraoperative Concerns

Hemodynamic instability - autonomic dysfunction + levodopa-induced dopaminergic/catecholamine effects can cause labile BP; exaggerated response to sympathomimetics (levodopa depletes central stores but increases peripheral dopamine/norepinephrine release - use vasopressors cautiously, start low)
Arrhythmias - levodopa can sensitize myocardium
Airway/ventilation - chest wall rigidity can reduce compliance; laryngeal/pharyngeal dysfunction increases aspiration risk
Hypothermia - impaired autonomic thermoregulation
Difficult positioning - rigidity and tremor may complicate patient positioning for surgery/regional blocks

Postoperative Management

Resume anti-Parkinsonian medications as soon as possible, same doses/timing as preoperative regimen; if NPO, use NG tube, dispersible levodopa, rotigotine patch, or apomorphine as bridge (involve neurology early)
Watch for acute akinesia/Parkinsonism-hyperpyrexia syndrome if medications delayed - treat with IV/NG levodopa, dantrolene/supportive care if it occurs (similar to NMS management)
Aggressive chest physiotherapy - high risk of postoperative pneumonia from weak cough and aspiration
Adequate analgesia (avoid pethidine with MAO-B inhibitors) - multimodal analgesia, regional techniques preferred to reduce opioid/sedative load
High risk of postoperative delirium/confusion - minimize deliriogenic drugs (anticholinergics, benzodiazepines), ensure early mobilization
DVT prophylaxis - immobility risk is higher
Early mobilization and swallowing assessment before resuming oral diet

Special Note: Patients with Deep Brain Stimulator (DBS) in situ presenting for non-neurological surgery

Turn off DBS device before using monopolar electrocautery (risk of device damage/tissue injury from induced currents); use bipolar diathermy if possible, and keep the electrocautery pad path away from the device
MRI is generally avoided/needs device-specific safety check
Do not apply magnets/programming devices carelessly
Battery-related device malfunction can precipitate acute severe Parkinsonism - have this anticipated and levodopa readily available

Viva Questions and Answers (Exam-Ready)

Q1. What is the pathophysiology of Parkinson's disease relevant to anaesthesia? A: Degeneration of dopaminergic neurons in substantia nigra pars compacta -> dopamine depletion in nigrostriatal pathway -> relative excess of cholinergic activity in the basal ganglia, producing bradykinesia, rigidity, tremor and postural instability. Associated autonomic neuron degeneration (Lewy body deposition in autonomic ganglia) causes orthostatic hypotension, GI dysmotility, and thermoregulatory dysfunction - all relevant to anaesthetic management.

Q2. Why should levodopa never be stopped abruptly before surgery? A: Levodopa has a very short half-life (60-90 min). Skipping even one dose can cause acute severe rigidity, akinesia, dysphagia (aspiration risk), and rarely a life-threatening Parkinsonism-hyperpyrexia syndrome (resembles neuroleptic malignant syndrome - hyperthermia, rigidity, autonomic instability, rhabdomyolysis). Hence continue up to and including the morning of surgery and resume ASAP postoperatively.

Q3. Name the drugs to avoid in a Parkinson's disease patient and why. A: Central dopamine (D2) antagonists worsen Parkinsonism: metoclopramide, prochlorperazine, droperidol, butyrophenones (haloperidol), typical antipsychotics. Pethidine should be avoided in patients on MAO-B inhibitors (selegiline/rasagiline) - risk of serotonin syndrome. Ketamine is used cautiously (psychotomimetic/sympathomimetic effects).

Q4. What is Parkinsonism-hyperpyrexia syndrome and how is it managed? A: Precipitated by abrupt withdrawal of dopaminergic therapy; presents with fever, severe rigidity, altered consciousness, autonomic instability, and rhabdomyolysis - clinically similar to neuroleptic malignant syndrome. Management: immediate reinstatement of levodopa (oral/NG/IV route), supportive cooling, hydration, dantrolene has been used, ICU-level supportive care.

Q5. Which induction agent is preferred and why? A: Propofol is generally preferred - it is safe, and interestingly has been reported to transiently suppress levodopa-induced dyskinesias, likely via GABAergic modulation. It does not exacerbate Parkinsonism. Etomidate is an alternative if haemodynamic instability is a concern.

Q6. Is succinylcholine safe in Parkinson's disease? A: Generally considered safe in most patients. Theoretical concern of exaggerated hyperkalemic response has been described in patients with severe rigidity/long-standing immobility (analogous to a denervation-like state), but this is not well substantiated and clinical practice does not universally avoid it. Caution is advised in advanced, severely immobile disease.

Q7. What are the anaesthetic implications of autonomic dysfunction in PD? A: Orthostatic hypotension (risk with induction and neuraxial blockade), impaired thermoregulation (risk of hypothermia), GI dysmotility (aspiration risk, delayed gastric emptying), impaired baroreceptor reflex response to blood loss/vasodilation - requires cautious fluid/vasopressor titration and invasive monitoring for major surgery.

Q8. Would you choose regional or general anaesthesia for a PD patient? A: Regional anaesthesia is preferred where feasible - avoids airway instrumentation, polypharmacy interactions, and permits continuation of oral medications. However, tremor/rigidity/dyskinesia may make positioning and prolonged stillness difficult, and autonomic dysfunction can cause exaggerated hypotension with sympathetic blockade. The choice depends on the type of surgery, severity of tremor, bulbar function, and patient cooperation. Neither technique is absolutely contraindicated.

Q9. What precautions are needed if the patient has a deep brain stimulator (DBS) and needs non-neurological surgery with electrocautery? A: Turn off the DBS device before using electrocautery. Prefer bipolar diathermy over monopolar; if monopolar is unavoidable, keep the grounding pad current path away from the device and leads. Avoid MRI unless device-compatible protocols are confirmed. Have anti-Parkinsonian medication readily available in case of device-related malfunction causing acute severe symptoms.

Q10. What are the airway concerns in a PD patient? A: Bulbar dysfunction causes dysphagia, weak cough, and poor airway protective reflexes, increasing aspiration risk. Rigidity of the chest wall reduces respiratory compliance. Upper airway obstruction from laryngeal muscle dysfunction can occur in advanced disease. Rapid sequence induction should be considered if significant dysphagia/reflux history is present.

Q11. How would you manage anti-Parkinsonian medications if the patient is NPO postoperatively? A: Resume medication via nasogastric tube using dispersible/liquid levodopa formulations as soon as possible. Alternative bridging strategies include transdermal rotigotine patch or subcutaneous apomorphine infusion, ideally started preoperatively and continued postoperatively in consultation with the neurology team, until the oral route is re-established.

Q12. What postoperative complications are PD patients at increased risk for? A: Aspiration pneumonia (weak cough, dysphagia), postoperative delirium/confusion (especially with underlying dementia, worsened by anticholinergics/benzodiazepines/deep anaesthesia), acute akinesia/Parkinsonism-hyperpyrexia syndrome if medications are delayed, DVT/immobility complications, and orthostatic hypotension with falls on mobilization.

Sources: Katzung's Basic and Clinical Pharmacology, 16e (General comments on drug management of parkinsonism); Goldman-Cecil Medicine (Interventional treatment, Parkinson disease); Textbook of Family Medicine 9e (Parkinson Disease); Bradley and Daroff's Neurology in Clinical Practice.

Recent evidence note: Current systematic reviews/meta-analyses in this area (PMID 38636468, PMID 38669414) focus specifically on anaesthetic technique (awake vs asleep, general vs local) for DBS implantation surgery itself, not on non-neurological surgery in PD patients - they do not contradict the management principles above but are not directly applicable to the non-neurological surgery scenario your exam question addresses.

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