Around a quarter of the burden of disease and injury resulting from illicit drug use is from poisoning or overdose1. Australia has a relatively low proportion of people who inject illicit drugs when compared to other countries. Despite the provision of needle syringe programs to minimize the risks of disease from dirty needles, almost 40% of users reported re-using their own needles3. Around 8% of users report developing an infection or abscess (excluding blood borne infections such as HIV and hepatitis C). Common complications resulting from overdose include hypoxia from central nervous system depression, particularly from heroin overdose, and aspiration pneumonitis due to failure to protect the airway.
Hypoxic brain injury is an unfortunate consequence of drug addiction and especially drug overdose. Many illegal drugs are central nervous system depressants, and overdose can lead to respiratory depression, respiratory arrest, and subsequent hypoxia. The early findings in CT scanning are those of cerebral oedema (Fig 1). Some drugs such as heroin have a vasospastic effect that can produce focal infarcts4. For those who survive the event, the long-term appearances are varying degrees of cerebral atrophy.
Aspiration pneumonitis and pulmonary oedema are also common in the abuse of several drugs. Aspiration frequently occurs in the setting of overdose, especially with central nervous system depressants (Fig 2).
Pulmonary oedema can occur with cocaine, opiates and methamphetamine abuse
5 (Fig 3).
Septic emboli can occur as a result of septic thrombophlebitis, infective endocarditis or injection of microorganisms with the drug5. Common sites for septic emboli include the chest (Fig 4) and brain.
Retained needle fragments are common with injecting drug users. Embolization of needle fragments is less common but has been reported4 (Fig 5).
Cocaine.
Cocaine is a stimulant drug that comes from the leaves of the coca bush (Erythroxylum coca), native to South America.6 It is commonly sold as a white powder or as crystals known as “crack” cocaine. The powdered form is typically inhaled or injected, and crack cocaine is usually smoked.
Cocaine-induced midline destructive lesion syndrome is a common complication of snorting cocaine7. About 5% of users will have a nasal septal perforation (Fig 6). The lesion can progress to destroy the palate, and nasal walls, producing a saddle-nose deformity, and eventually to necrosis of the midface.
Cocaine causes cerebral vasospasm, and significantly reduces cerebral blood flow8. Cocaine abuse is also associated with both parenchymal and sub-arachnoid haemorrhage9 (Fig 7), which are twice as common as ischaemic events10.
“Crack lung” is an acute pulmonary syndrome that occurs within 48 hours of smoking crack cocaine11. Patients present with dyspnoea, chest pain, haemoptysis and/or fever. CT shows diffuse alveolar and interstitial opacites, often ground-glass in nature (Fig 8), and occasionally with small pleural effusions11, 12. The appearances clear with cessation of the drug. Pneumomediastinum is also seen with crack cocaine smoking13.
Gamma Hydroxybutyrate.
GHB (gamma hydroxybutyrate, “fantasy”) is a synthetic depressant drug which usually comes as a colourless liquid, a bright blue liquid known as “blue nitro”, and less commonly as a crystal powder14. It is usually taken orally. GHB gives users a combined stimulant and sedative affect, combined with sexual arousal15.
The majority of hospital presentations for GHB relate to reduced consciousness. There is little published data on the imaging of the brain in GHB toxicity, but the limited research suggests that damage occurs from GHB-induced comas rather than GHB itself15-17 (Fig 9).
Heroin.
Heroin is an opioid, a naturally occurring narcotic derived from the opium poppy. It is sold as a fine white powder, coarse off-white granules, or tiny pieces of light brown rock18. Heroin is usually injected but can also be smoked, known as “chasing the dragon”.
Heroin smoking or inhalation produces a unique leukoencephalopathy that does not occur with injection or oral ingestion of the drug10. Although rare, the condition has a mortality of around 25%19. Acute clinical symptoms include restlessness, speech disturbance and ataxia. The subacute phase includes worsening cerebellar symptoms, hypertonic reflexes, spasticity, tremor and choreo-athetoid movements. In the chronic/preterminal phase, hypotonia, areflexia and respiratory failure ensue20. MRI shows high T2 signal in the globus pallidus, and the white matter of both the cerebellum and cerebrum10 (Fig 10 and 11).
Methamphetamines.
Amphetamines are synthetic psychostimulant drugs. Methamphetamine is generally swallowed, injected, or smoked. It can also be inhaled. The most potent form is “crystal meth” or “ice”18.
Amphetamines cause vasoconstriction and increased cardiac output, which can lead to severe hypertension. This is one of the leading causes of cerebral haemorrhage in meth users5 (Fig 12).
Amphetamine use is also associated with ischaemic events and posterior reversible encephalopathy syndrome
21, 22 (Fig 13).
Methylenedioxymethamphetamine.
Methylenedioxymethamphetamine (MDMA) is an amphetamine derivative empathogen, commonly known as “ecstasy”. However, some pills sold as ecstasy may only have a small amount of MDMA or none18. MDMA is usually swallowed in a tablet or capsule form but can also be a powder or crystal.
The main cerebral complications of MDMA are ischaemia and stroke9 (Fig 14).
Vasospasm and arteritis have also been reported, along with reduced cerebral blood flow to the occipital cortex and globus pallidus.
23
Pneumomediastinum has also been reported, and relates to increases in intrathoracic pressure from drug inhalation and drug-related seizures24 (Fig 15).
MDMA can also have a vasoconstrictive effect on the splanchnic vasculature5. Multiple cases of gut ischaemia associated with MDMA have been reported, as well as distal colon perforation from pressure necrosis due to constipation5 (Fig 16).
Nitrous Oxide.
Nitrous oxide is a dissociative anaesthetic gas which is inhaled. It is also a food additive used as a propellant for whipped cream, and is used in the automotive industry to enhance engine performance25. As such, it is readily available for purchase legally. Also known as “laughing gas”, it is used for the feeling of euphoria that is felt almost immediately. Nitrous oxide toxicity can result in subacute combined degeneration of the spinal cord. Imaging findings include high T2 signal in the posterior columns of the spinal cord, in the setting of nitrous oxide abuse9 (Fig 17). The imaging findings can also occur in other settings including vitamin B12 deficiency and demyelination.
Internal Drug Concealment.
Internal drug concealment or “body packing” is used to smuggle illegal drugs, typically across international borders. Drugs are usually swallowed, as well as being inserted into the rectum and vagina. The drugs are typically double wrapped in condoms or pieces or latex gloves26. Unfortunately for the drug mule, the packages frequently leak or rupture, resulting in the drugs being absorbed into the body. The results are often fatal. Packages can sometime be identified on plain x-ray, but CT scanning is the most effective method of identifying both the location and number of packages in the body27-29 (Fig 18). While heroin and cocaine can be differentiated using dual-energy CT30, it is not routinely used as the drugs are tested post removal for forensic purposes.