Different routes of heroin intake cause various heroin-induced leukoencephalopathies

Bilateral middle cerebellar peduncle lesions: Neuroimaging features and differential diagnoses

“…Oligodendrocyte apoptosis‐induced demyelination in the white matter is more sensitive to ischemia/hypoxia because the axons and myelin sheaths in this area are thin (Yin et al., 2013). Therefore, in agreement with the pathological findings, brain MRI abnormalities caused by heroin inhalation often result in extensive, symmetrical lesions of the cerebral and cerebellar white matter, posterior limbs of the internal capsules, and splenium of the corpus callosum, which helps distinguish it from other causes of leukoencephalopathy such as toluene toxicity or reversible posterior leukoencephalopathy (Alambyan et al., 2018; Cheng et al., 2019; Offiah & Hall, 2008). Our patient, who had an extensive medical history of heroin inhalation with presentations ranging from confusion to coma, exhibited these specific bilateral symmetrical lesions in the posterior limbs of the internal capsules, while the anterior limbs were spared, consistent with the aforementioned observations.…”

“…"Chasing the dragon," an inhalation method that involves heating heroin over aluminum foil and inhaling the resultant fumes, has recently become the most popular route of heroin intake due to its availability, greater ease of administration, and safer infectious profile compared to the other routes (Cicero, Ellis, Surratt, & Kurtz, 2014). A recent study showed that the brain MRIs of patients with heroin-induced leukoencephalopathy differed greatly according to the intake routes (Cheng, Chin, & Chang, 2019): The MRI findings of patients who inhaled heroin were characterized by posterior to anterior involvement of the cerebral white matter and lesions in the posterior limbs of the internal capsules, cerebellum, and brainstem, whereas those of patients who injected heroin IV were characterized by lesions in the subcortical U-fibers and genu of the internal capsule. The definitive mechanism underlying heroin-induced leukoencephalopathy remains unclear.…”

“CHOICES”: An acronym to aid in delineating potential causes of non-metabolic, non-infectious acute toxic leukoencephalopathy

“…methadone, fentanyl) [20]. Hence, for the purposes of the ‘CHOICES’ acronym, we separate heroin-induced LE (usually intravenous or inhaled) from the opioid analogues (typically oral or intravenous), as the original descriptions of toxic LE from illicit opioids are largely based on heroin usage, as opposed to medication abuse [[21], [22], [23]]. A confounding issue in identifying the etiology of ATL can be when heroin or other opiates occur in tandem with other illicit drugs (such as cocaine), making it difficult to discern which is the causative etiology; such instances with a positive urine sample having an ‘unspecified opioid’ occurred as the cause in 9/87 patients (10.3%) in this study [2,3].…”

“…Clinically, whether intravenous or inhaled, heroin-induced ATL may progress through stages, beginning with a cerebellar syndrome, while the other end of the spectrum is a final clinical stage of symptomatology that includes spasms, akinetic mutism, and possibly death [20]. Characteristic areas of inhaled heroin-induced ATL (so-called “chasing the dragon”) include the posterior cerebral WM, the internal capsule’s posterior limbs, and occasionally cerebellar WM, whereas the subcortical U fibers and the internal capsules’ genu are more frequently involved in intravenous heroin-induced neurotoxicity [2,3,5,22]. Depending on the severity, lesions progress symmetrically from the deep PVWM to the subcortical WM, often spreading posterior to anterior; this can be entirely reversible, particularly in intravenous exposures [2,24].…”

Heroin-Induced Leukoencephalopathy

“…As the name implies, this disease is secondary to heroin use. Although it is most commonly seen in heroin users who inhale the fumes of the heated heroin powder on a piece of aluminum foil, it can also be seen in people who inject or snort heroin as well [1][2][3]. Even though heroin history can be dated back to the 1950s, the disease was first reported by a cohort study from the Netherlands [4].…”