‘Chasing the dragon’
Inhaling heroin vapor is known by drug users as “chasing the dragon.” Users place a small amount of heroin powder on aluminum foil, which they heat from below with a flame. The heroin liquidizes and emits a white vapor, which users inhale.3
This method of heroin use can result in a form of toxic spongiform leukoencephalopathy. Brain imaging shows widespread white matter hyperintensities involving both supra and infratentorial compartments that are considered highly specific for this type of leukoencephalopathy ( Figure ). These hyperintensities are most commonly found in the:
- posterior cerebral and cerebellar white matter
- cerebellar peduncles
- splenium of the corpus callosum
- posterior limb of the internal capsule.4
Involvement of the cerebellum and posterior limb of the internal capsule while sparing the anterior limb helps to distinguish heroin vapor inhalation from other causes of toxic leukoencephalopathy.3 Extensive damage to the white matter is believed to be caused by a contaminant that is activated when heroin is heated.4,5
Toxic leukoencephalopathy has not been observed in heroin users who snort or inject the drug. Despite the prevalence of heroin abuse, fewer than 100 cases of leukoencephalopathy associated with heroin vapor inhalation have been reported as of 2000, the most recent year for which data are available.6 Patients with this form of leukoencephalopathy typically progress through 3 clinical stages: initial, intermediate, and terminal ( Table 2 ).4
Figure: White matter changes in a patient who inhaled heroin vapor
Photos: © Frank Gaillard/Radiopaedia.org
Seen on brain MRI as ultra-white patches, white matter hyperintensities (WMHs) are areas of increased signal intensity that indicate injury to the axons. In this typical patient (not Mr. G) who developed toxic leukoencephalopathy from heroin vapor inhalation, WMHs are evident in supra and infratentorial compartments, with characteristic involvement of the posterior limb of the internal capsule and cerebellum. Table 2
Stages of heroin vapor inhalation leukoencephalopathy
| Stage | Features |
|---|---|
| Initial | Soft (pseudobulbar) speech, cerebellar ataxia, motor restlessness, apathy/bradyphrenia |
| Intermediate | Pyramidal tract lesions, pseudobulbar reflexes, spastic paresis, tremor/myoclonic jerks, choreoathetoid movements |
| Terminal | Stretching spasms, hypotonic paresis, akinetic mutism, central pyrexia, death |
| Source: Reference 4 | |
TREATMENT Stimulant medication
We prescribe methylphenidate, 2.5 mg bid, to which Mr. G responds well. His cognition and mood improve, he is more goal-directed in his responses, and his MMSE score increases to 13/30. Mr. G eventually is able to converse minimally, and he confirms that he had heated heroin on a piece of foil and inhaled the vapors through his mouth.
Mr. G reports on the day of discharge that he still has cravings for illicit drugs and plans to continue using them. He is not interested in chemical dependency treatment.
The authors’ observations
Little published data exist on treating toxic leukoencephalopathy. Treatment mainly is supportive, although some researchers have suggested a role for coenzyme Q and vitamin supplements.3
Some studies have found methylphenidate beneficial in treating cognitive slowing in cancer patients.1,7 The extent of Mr. G’s cognitive impairment—which was severe—and evidence supporting stimulant medication prompted us to prescribe a low-dose methylphenidate trial, even though we were well aware of its abuse potential. Mr. G improved after starting methylphenidate, but unfortunately he was lost to follow-up.
Related resource
- Filley CM, Kleinschmidt-Demasters BK. Toxic leukoencephalopathy. N Engl J Med. 2001;345(6):425-432.
Drug brand name
- Methylphenidate • Ritalin
Disclosures
The authors report no financial relationship with any company whose products are mentioned in this article or with manufacturers of competing products.