SAN DIEGO — In the clinical opinion of Jenny E. Murase, MD, .
“The fact that delusional infestation is a fixed, false belief [means] we will never agree with patients on the etiology by definition,” Dr. Murase, a dermatologist with the Palo Alto Foundation Medical Group, Mountain View, California, said at the annual meeting of the American Academy of Dermatology. “But somehow, we must come to some kind of an agreement on how to approach this therapeutically.”
Dr. Jenny E. Murase
Patients with delusional infestation (DI) often describe a cutaneous sensation of itching or crawling, biting, stinging — a pins and needles sensation. “Formication is when there’s a crawling sensation on the surface of the skin,” she said. “That’s something we can agree on — the fact that there is a shared understanding that they’re experiencing some kind of sensation in their skin.”
First described in 1894, several different terms have been used to describe DI in the past, including acarophobia, delusions of parasitosis, Ekbom syndrome, and Morgellons disease. The current term used for DI includes other animate or inanimate pathogens besides parasites.
The average dermatologist manages two to three patients with DI every 5 years, “so it’s not uncommon,” said Dr. Murase, who also holds a faculty position in the department of dermatology at the University of California, San Francisco. Females are about 2.5 times more likely to be affected compared with males, she said, and 8%-12% of patients with DI have a friend or relative who shares the symptom, and they often accompany them to the office visit. “Initially, you’re trying to determine if this a primary condition where it’s only the cutaneous condition the patient is experiencing, or if there is a secondary condition like an underlying psychiatric disorder or medical condition or drug use that contributes to the sensation,” she said.
According to a descriptive study of 115 patients with DI, 50% had at least one drug detected in hair samples, and nearly 60% had evidence of some cognitive impairment that could not be explained by deficits in IQ. Another study of 147 patients with DI seen at the Mayo Clinic between 2001 and 2007 found that 81% had a prior psychiatric condition and 26% had a shared psychotic disorder.
Phased Approach to Treatment
Dr. Murase discussed her phased approach to caring for patients with DI, based on a review article that she and colleagues published in the International Journal of Dermatology. Phase 1 involves preparing for the visit by asking staff to refer to patients with DI as VIPs and allowing them to talk freely about the sensation they’re experiencing. “The goal is to improve the patient’s condition, not to convince the patient that he or she is delusional,” Dr. Murase explained. “Many patients can’t distinguish between when they’re talking to the doctor and when they’re talking to a nurse or a nurse practitioner; they like to feel that they’re being heard and listened to.”