Objective:

Dystonia may be a manifestation of methadone withdrawal.

Background:

Methadone withdrawal has not heretofore been described to induce
dystonia.

Design/Methods:

This 39 year old woman without a history of movement
disorder, presented with use of 140 mg of methadone per day for 4 1⁄2 years. Two days
prior to admission, she used heroin, 1⁄2 gram intravenously. Upon admission, her
methadone was dropped to 100 mg per day. Two days later she developed trismus and
spasms of the back and legs, acutely responding to 50 mg diphenhydramine
intramuscular, shortly thereafter the spasms recurred. This required three additional
injections at which point the generalized spasms were resolved. The trismus and muscle
spasms recurred multiple times a day over the next three days, responding to
intramuscular diphenhydramine. Because of the persistent dystonic symptoms, the
methadone was raised to 140 mg a day at which
point the dystonic movements resolved and have not recurred.

Results:

Urine toxicology screening: positive for heroin, opioids, methamphetamine and
cocaine.

Conclusions:

Opioids, including methadone act on the ventral tegmental area inhibiting
GABAA interneurons, thus disinhibiting dopamine neurons, causing dopamine release,
leading to dystonia. Methadone withdrawal enhances GABAA interneuron firing,
leading to a reduction of dopamine release, and a relative dopamine depletion state. A
dopamine depleted state is not known to cause dystonia, but rather parkinsonoid-like
features. This conundrum can be explained with the assumption that dystonia is not from
the striatum but rather from the cerebellum (Le doux, 2022). Dystonia has been
postulated to be primarily due to abnormalities in the cerebellar-basal
ganglia-thalamo-cortical circuit (Gianni, 2022). In those who present with acute dystonia,
query as to methadone use and withdrawal is
warranted and in those who are on methadone whom develop dystonia, treatment with
increasing methadone dosage may be worthwhile.