What is known about Mb Parkinson and ketamine (Ketalar)?/nA patient with Mb Parkinson treated with

Fråga: What is known about Mb Parkinson and ketamine (Ketalar)?

A patient with Mb Parkinson treated with levodopa and the decarboxylase inhibitor benserasid (Madopark) now requires general anaesthesia. The patient also has a mental disorder with confusion.

Sammanfattning: Mb Parkinson is not considered to be a contraindication for the use of ketamine anaesthesia. However, the involuntary movements induced by ketamine might be due to increased dopamine activity and an increased risk for hyperkinesia cannot be excluded in patients given dopamine substitution.

Svar: Ketamine is a general anaesthetic agent that produces a state of dissociative anaesthesia. The mechanism of action is not fully understood. It increases muscle tone and sudden involuntary jerky movement of large muscle groups can occur, which may resemble convulsions (1). Other reactions are also common during recovery from ketamine anaesthesia, such as unpleasant dreams, confusion, hallucination and irrational behaviour (2). Ketamine causes an increase in both cerebral blood flow and cerebral oxygen uptake. This accounts for the concomitant increase in intracranial cerebrospinal fluid pressure. Stated contraindications to ketamine use are raised intracranial pressure and a history of psychiatric disorders. Nothing is mentioned about Mb Parkinson as a contraindication in common text books (1,2).

We have done a thourough Medline search using ketamine and basal ganglia diseases, dopamine, parkinson disease and dyskinesia as search words. We have not found any human studies of interest. In one study in mice the underlying mechanisms of ketamine induced hyperlocomotion was examined. The hyperactivity was inhibited by a low dose of haloperidol, a dopamine (DA) receptor antagonist. Regional brain monoamine assays reveal that a low dose of ketamine selectively increased dopamine turnover in the nucleus accumbens which is a forebrain region believed to be involved in initiation and regulation of locomotor activity (3).

In Parkinsons disease there is an insufficient amount of dopamine in the basal ganglia. When substitution with levodopa is given, hyperkinesia is seen as a common adverse reaction and is considered a sign of overdose (4).