Central anticholinergic syndrome (CAS)Dr. S. Parthasarathy

MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics,Ph D

(physiology) Mahatma gandhi medical college and research institute, puducherry, India

• Central anticholinergic syndrome (CAS) is a clinical entity

• which shows central and peripheral effects produced by over dosage

• or abnormal reaction to clinical dosage of anticholinergic drugs

Symptoms • Central

• Peripheral

• Lowest age reported is 4

Central - Young patients

Central old patients

Central • Agitation • Amnesia• Ataxia• Asynergia • Confusion,excitement • Hallucinations• Delirium • Somnolence

Central • Nausea• Emotional instability• Hyperpyrexia,• Hyperalgesia • Convulsions • Muscle incoordination

Peripheral • Dry mouth • Dry skin • Arrhythmias• Mydriasis • Blurred vision • Micturition and bowel dysfunction• Thirst

• Almost no symptom is spared

Basic mechanism • Cholinergic synapses necessary for

memory • and anticholinergics ??• Acetylcholine and anaesthetics • GABA modifies Cholinergic synapses • EEG behavioral dissociation

Incidence • After GA, 9.4 %• After RA with sedation 3.3 % • Reported from 4 year child onwards • From Immediate postop to first week

Old age- more incidence • The decreased cholinergic reserve in

older persons

• Other drugs

Drugs and CAS • Antidepressants • Anticholinergics • Antipsychotics • Antispamodics • Halo,enflurane • Morphine, pethidine • Ketamine • Antiparkinson drugs

What is this ??• An elderly patient is scheduled for

enucleation of a blind, painful eye. Scopolamine, 0.4 mg IM, premedication.

• preoperative holding area, the patient becomes agitated and disoriented.

• The only other medication the patient has received is 1%atropine eye drops.

Differential diagnosis • Metabolic encephalopathy • ABG, renal parameters ,electrolytes

• Neurologic damage • CT scan

How to conclude as CAS • Method of exclusion • Profile • Physostigmine challenge

• 0.04 mg / kg IV or IM • 5 – 15 minutes symptoms improve

Physostigmine • A cholinesterase inhibitor• Rapidly hydrolysed • Raised BP and tachycardia !!

• No problem with neostigmine • Analgesia • Usually one dose is enough •

Other drugs • Galantamine hydrobromide • 4 amino pyridine • Tacrine

• But nonspecific

Delayed recovery • naloxone and flumazenil,

• Usually the patients recover to go back to sleep

• In CAS , recovery after physostigmine is usually complete

How to avoid ??• Atropine • Phenergan • Physostigmine just before recovery

Acta Anaesthesiol Belg. 1976;27(2):45-60

• treated 200 cases in which the CAS was diagnosed with physostigmine salicylate (0.04 mg/kg).

• successfully treated 2 cases of apparently central anticholinergic hyperpyrexia in the same way.

• suggest that physostigmine be included in the armamentarium of every anesthetist

Thank you all