Neurological abnormalities in opiate addicts with and without substitution therapy

Opiate addicts are generally prone to comorbidities, including neurological disease, because of the toxic effect of the drug, the combined use of opiates, and other neurotoxic substances, infections, bacteriemia from intravenous drug use, atherosclerosis from smoking or hyperlipidemia, trauma, reduced primitive reflexes during intoxication, compression neuropathies, rhabdomyolysis, or rhythm abnormalities and heart failure.

Few data are available about neurological abnormalities in opiate addicts.

Consecutively included were all in- and outpatients of the Department for Drug Disease, Otto Wagner Hospital, Vienna, Austria, between 2003 and 2005, with and without an opiate substitution therapy. All patients underwent a clinical neurological examination alternatively by two trainees.

A total of 460 patients (110 women, 350 men) aged 17-54 years were investigated. Opiate consumption lasted <2 years in 19 patients, 2-8 years in 187 patients, and >8 years in 196 patients. In 58 patients, no information about the duration of opiate consumption was available. Of the 460 patients 407 were under an opiate substitution therapy, 53 without. The neurological history was positive for epilepsy in 68 and for head trauma in 18 cases. The most frequent abnormalities were abnormal, dysdiadochokinesia, impaired stance, resting tremor, and miosis. The number of neurological abnormalities most frequently found in a single patient was eight (n = 269 patients). The number of neurological abnormalities increased with duration of addiction. The neurological diagnoses most frequently established were epilepsy (n = 22), polyneuropathy (n = 12), and pressure palsies (n = 4). Absence of direct or indirect reaction to light, miosis, abnormal heel-to-knee test, lower limb sensory disturbances, and unsafe gait were more frequent in patients under substitution than in patients without and vice versa for mydriasis, myopia, and resting tremor.

All opiate addicts under substitution therapy present with neurological abnormalities. The high prevalence of neurological abnormalities in opiate addicts implies regular referral of these patients to the neurologist to improve their outcome.