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Parkinson's disease

The pathophysiology of PD is a loss of dopaminergic neurones in the pars compacta region of the substantia nigra, leading to the classical motor symptoms of parkinsonism:

it is a multi-system neurological disorder which causes disabling motor, neuropsychiatric, and autonomic dysfunction

Withdrawal

parkinsonism-hyperpyrexia syndrome (PHS), due to withdrawal of levodopa. Symptoms mimic those of neuroleptic malignant syndrome:

dopamine agonist withdrawal syndrome (DAWS). Symptoms include:

System Anaesthetic relevance
Airway – Upper airway dysfunction (due to laryngeal/pharyngeal muscle dyskinesia) contributes to retained secretions, atelectasis, aspiration, post-extubation laryngospasm

– Fixed flexion deformity of neck, which may impair laryngoscopic view
Respiratory – Restrictive pulmonary deficit, due to rigidity, bradykinesia, or dyskinesia of respiratory muscles

– OSAS common
Cardiovascular – Cardiac arrhythmias

– Orthostatic or exercise-induced hypotension, which may be due to PD or anti-parkinsonian drugs, increased risk of intraoperative hypotension
CNS – Greater risk of postoperative delirium and hallucinations
Gastrointestinal – Dysphagia, which contributes to aspiration pneumonia and malnutrition

– Sialorrhoea (drooling) is a sign of advanced PD, but is thought to be a motor symptom (which impairs swallowing), rather than an excess of salivation. May need a drying agent before operation, for example, glycopyrrolate. Antimuscarinic (e.g. neostigmine) drugs increase the viscosity of saliva, thus further impairing swallowing

– Increased prevalence of GORD

– Postoperative ileus or delayed gastric emptying may result in reduced absorption of enteral anti-parkinsonian drugs
Urological – Increased risk of postoperative urinary tract infection

Peri-op drug Mx

The guiding principle of the perioperative pharmacological management of PD patients is to maintain CNS dopamine receptor activation. In most cases, this can be achieved by continuing the patient's usual anti-parkinsonian drug regime into the perioperative period: allowing patients to take their drugs up until anaesthetic induction, that is, within the ‘nil-by-mouth’ period with a sip of water, utilizing anaesthetic techniques which enable a rapid return to oral intake, for example, central neuraxial block, or by administering drugs enterally via a nasogastric tube (NB for dispersible preparations only—due to the differing bioavailabilities, a 30% dose reduction is suggested if the patient usually takes modified-release preparation). PD patients should usually be placed first on the operating list, so that the timing of drug administration is predictable, the risk of cancellation is minimized, and to ensure optimal early postoperative disease management.

Intra-op

Mode of anaesthesia Advantages Disadvantages
Central neuraxial block Intraoperative monitoring of parkinsonian symptoms Muscle rigidity may make positioning difficult
Further oral medication may be given intraoperatively May be technically challenging with severe resting tremor
Earlier return to postoperative oral intake Risk of hypotension, especially in those with autonomic dysfunction
Reduced use of systemic opioids, which may otherwise decrease gastrointestinal absorption Tremor will only be abolished in the areas with motor block—tremor elsewhere may hinder surgery and affect monitoring
Neuromuscular blocking agents not required, so no need for anticholinergic reversal agents
General anaesthesia Tremor is eliminated Postoperative nausea and vomiting may preclude adequate dosing of anti-parkinsonian medication
General anaesthesia in combination with dysphagia and ineffective cough is more likely to result in postoperative pneumonia

Monitoring

A significant tremor may induce monitoring artifacts: the ECG trace may mimic atrial flutter or ventricular fibrillation, and it may be difficult to measure arterial pressure non-invasively.
Excessive sweating due to autonomic dysfunction may result in poor ECG electrode contact.

Induction of anaesthesia.

Just as in the general population, propofol may cause dyskinetic movements in PD patients. But propofol is also an anti-emetic and temporarily suppresses the parkinsonian resting tremor, and is therefore probably the best choice of induction agent in most situations.
Thiopental and ketamine have been used in PD patients without harm, despite theoretical risks of exacerbation of parkinsonian symptoms and exaggerated sympathetic response, respectively.
With the exception of halothane, which potentiates levodopa-induced arrhythmias, the volatile anaesthetic agents are safe. Whichever drug is used for induction of anaesthesia, it is important that it is used judiciously: perioperative hypotension can be difficult to manage, and is especially common in the presence of autonomic dysfunction or dehydration.

Neuromuscular block

NMBA in general safe
But residual block in the immediate postoperative period can mask parkinsonian symptoms, and neostigmine should be used with caution due to its thickening action on airway secretions. Perhaps, the ideal agent is rocuronium, as it may be reversed by sugammadex.

Opioids

if on MAOI → should not use pethidine ∵ risk of Serotonin syndrome
high dose strong opioid bolus may lead to rigidity

Pharmacological

Contraindicated

Airway

Sialorrhoea can complicate airway management, and may be reduced with glycopyrrolate. Intubation should be considered if dysphagia is suspected. There is an increased prevalence of gastroparesis and gastrooesophageal reflux disease in PD patients, which may necessitate rapid sequence induction. Laryngoscopy may be difficult in the presence of a fixed flexion deformity of the neck.

Anti-emetics

A number of commonly used anti-emetics are contraindicated in PD, due to dopamine antagonist effects. 5-HT3 receptor antagonists, for example, ondansetron, and histamine H1-receptor antagonists, for example, cyclizine, have fewer side-effects. Despite being a dopamine receptor antagonist, domperidone does not readily cross the BBB and so is safe to use in PD.

Surgical diathermy

PD patients with an implanted DBS will occasionally present for surgery. Surgical diathermy is not contraindicated, but can damage the DBS leads, or can cause suppression or reprogramming of the neurostimulator.
If surgical diathermy is necessary, the neurostimulator device should be switched off immediately before induction of anaesthesia, and bipolar diathermy should be used. Post-operatively, the neurostimulator should be checked to confirm normal function.

Post-op

PONV
delirium

References

Parkinson's Disease BJA Ed