Pruritus after intrathecal baclofen withdrawal: A retrospective study.
OBJECTIVE
To determine the frequency of pruritus after intrathecal baclofen (ITB) withdrawal and to study the pathophysiology of this symptom.


METHODS
Retrospective cohort study.


METHODS
Rehabilitation department of a general hospital.


METHODS
Patients (N=102) implanted with an ITB pump who had been followed up since 1988.


METHODS
Not applicable.


METHODS
Incidence of pruritus after withdrawal. We studied the relation between pruritus and daily dose, concentration and mode of infusion of baclofen, and cause of the central nervous system lesion inducing spasticity.


RESULTS
Pruritus was observed in 10 of 23 cases of ITB withdrawal. It never occurred during the first 3 months after pump implantation. It seems likely that the segmental spinal action of baclofen is responsible for pruritus. There was no statistically significant difference between patients with ITB deprivation who did and did not experience pruritus in their daily infused dosage or in concentration and mode of infusion. Surprisingly, no pruritus was observed in patients with multiple sclerosis.


CONCLUSIONS
Pruritus is a frequent symptom after ITB withdrawal. Its occurrence is probably subsequent to chronic blocking of the liberation of substance P by baclofen at the spinal level. This symptom is a good clinical predictor of baclofen withdrawal, in contrast to an isolated increase of spasticity that may be due to drug tolerance or irritant factors. Pruritus requires investigation of a possible dysfunction of the infusion system.
Ben Smail
Djamel
D
Service de Médecine Physique et Réadaptation, Hôpital Raymond Poincaré, AP-HP, Garches, France.
Hugeron
Caroline
C
Denys
Pierre
P
Bussel
Bernard
B
D001418:Baclofen / Q000008:administration & dosage / Q000009:adverse effects*; D018755:GABA Agonists / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D015918:Infusion Pumps, Implantable; D007278:Injections, Spinal; D009128:Muscle Spasticity / Q000139:chemically induced / Q000453:epidemiology; D011537:Pruritus / Q000139:chemically induced* / Q000453:epidemiology / Q000503:physiopathology; D012189:Retrospective Studies; D013373:Substance P / Q000378:metabolism; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*
D018755:GABA Agonists; D013373:Substance P; D001418:Baclofen