CASE: Hurt and confused
Emergency medical services (EMS) are called to Ms. K’s apartment after her roommate found her lying on the floor moaning. The roommate tells EMS that Ms. K, age 29, appeared confused and was slurring her words, and reports that this change in her awareness progressed rapidly over a few hours. EMS personnel find that Ms. K has multiple contusions on her arms and face, which they presume to be self-inflicted. A marijuana pipe is discovered at Ms. K’s apartment.
In the emergency room (ER), Ms. K is inattentive and has difficulty following simple commands. Her speech is mumbled and her thoughts are disorganized. She displays psychomotor restlessness in the form of combativeness. Ms. K cannot provide meaningful historical data and is disoriented to place and time. The ER staff requests a psychiatric consultation.
Family members reveal that Ms. K has no preexisting medical conditions, is not taking prescription medications, but has a history of substance abuse (sporadic cocaine and cannabis use). Her family is unaware of recent substance use.
Physical examination reveals tachycardia (heart rate 110 to 120 beats per minute), hypotension (blood pressure 78/49 mm Hg), hypothermia (temperature 88ºF), and peripheral pulse oximetry of 84%. Her pupils are dilated and reactive to light; no conjunctival injection is noted. Her lung fields are clear on auscultation, but she is noted to have a rapid, irregular heartbeat. The abdomen is positive for bowel sounds, soft on palpation, and without any repositioning or notable overt signs of tenderness. Ms. K’s toes show purple discoloration with poor capillary refill. The dorsalis pedis pulses are reported to be 1+ bilaterally; however, the remainder of the arterial pulse examination is normal.
Her sodium, potassium, and chloride values are normal, but she has an abnormal anion gap (28.1 mEq/L), blood urea nitrogen (53 mg/dL), creatinine (2.9 mg/dL), creatine kinase (10,857 U/L), creatine kinase MB (432.6 ng/mL), and hyperglycemia (glucose 425 mg/dL). Arterial blood gas reveals hypoxia (Po2 of 55 mm Hg), with metabolic acidosis (sodium bicarbonate 10 with compensatory Pco2 of 33 mm Hg). Her urine is cloudy, positive for protein, ketones, hemoglobin, and glucose. She is thought to have a high anion gap acidosis related to dehydration, lactic acidosis (lactic acid 20 mEq/L), and hyperglycemia. Urine toxicology is positive for cannabinoids; ethylene glycol and methanol screen negatively, which rules these out as potential contributors to her high anion gap acidosis.
Ms. K is intubated and IV fluids are initiated for rhabdomyolysis and acute renal failure. Dialysis is implemented on a short-term basis. Her mental state improves gradually over 3 days.
The authors’ observations
Based on the abrupt onset of inattention and confusion, disorganized speech, memory impairments, and psychomotor agitation, we made an initial diagnosis of delirium; however, the precise etiology remained unclear. DSM-IV-TR diagnostic criteria for delirium are described in Table 1. Although delirium due to multiple etiologies does not have a DSM-IV-TR coding designation, we speculated that multiple causes contributed to Ms. K’s presentation. Acute renal failure secondary to dehydration as well as rhabdomyolysis, hypoxia, and hyperglycemia were implicated as general medical conditions etiologically linked to delirium. Because Ms. K has no preexisting medical conditions and her roommate and family stated she had a history of substance abuse, we also considered a presumptive diagnosis of substance-induced delirium. The medical team speculated that, based on information provided by her family, Ms. K may have had a seizure or may have fallen, which would account for her multiple contusions, and could have led to muscle injury and breakdown and the resultant rhabdomyolysis.
The possibility of cannabinoid-induced delirium has been reported, albeit rarely.1-3 However, Ms. K’s presentation—hypothermia, variable heart rate, lack of dry mucous membranes—was not consistent with significant anticholinergic toxicity or cannabinoid intoxication (Table 2).
By contrast, cocaine-induced delirium has been reported and initially appeared to be a plausible cause of Ms. K’s symptoms (Table 2). Delirium related to excess ingestion of cocaine may be related to the drug’s secondary effects resulting in rhabdomyolysis and renal dysfunction.4-6 Although several mechanisms underlying this relationship have been proposed, no single specific mechanism has been identified. The basis for cocaine ingestion and the resultant metabolic and renal effects, as observed in Ms. K’s case, likely are multifactorial. Mechanisms of the rhabdomyolysis might include:
- blockade of synaptic catecholamine reuptake and induction of adrenergic agonism, resulting in vasoconstriction and ischemia and leading to muscle damage
- cocaine-induced seizures and/or prolonged unconsciousness, leading to muscle compression and breakdown of muscle tissue
- a period of exertion induced by cocaine, precipitating an excited delirium and associated rhabdomyolysis
- a surge in dopamine concentrations, similar to neuroleptic malignant syndrome, precipitates hyperthermia, muscle rigidity, and psychomotor agitation, disrupting neuromuscular homeostasis and leading to rhabdomyolysis.