Assessment of local pain and analgesia in envenoming by wandering spiders (Phoneutria spp.)

Abstract

Phoneutrism (bites by wandering spiders of the genus Phoneutria) frequently results in local pain. We describe a retrospective cohort study of a case series of phoneutrism admitted to our Emergency Department (ED), in which we used the Numeric Pain Rating Scale (NPRS 0-10) to assess the intensity of local pain upon admission, and recorded the analgesic measures used to control this pain. Other criteria for inclusion were: (1) An age ≥8 years, (2) Treatment exclusively at our ED, and (3) Visualization or photographing the spider at the time of the bite and/or bringing the spider for identification. The patients were classified into three groups based on the intensity of pain at admission: group 1 - mild or no pain (NPRS: 0-3), group 2 - moderate pain (NPRS: 4-6), and group 3 - intense or severe pain (NPRS: 7-10). Fifty-two patients fulfilled the inclusion criteria (n = 11, 14 and 27 in groups 1, 2, and 3, respectively), with a median age of 37 years. The median NPRS upon admission was 7 (interquartile range: 5-8). In patients with an NPRS <7 (groups 1 and 2), only dipyrone was used to alleviate the pain, with six cases in group 1 requiring no analgesia. Most of the cases in group 3 (19/27) were treated with a local anesthetic infiltration (2% lidocaine), in association with analgesics given i.v. in 16 cases (dipyrone, 14; tramadol, 2); additional analgesic treatment was required in seven cases, six of which were treated with tramadol i.v. The median time spent in the ED was 18, 58 and 120 min for groups 1, 2 and 3, respectively. These findings show that most cases of envenoming by Phoneturia spp. involved intense local pain (NPRS ≥7), with local anesthetics being used only in these cases, often in association with dipyrone i.v.

Keywords: Analgesia; Dipyrone; Envenoming; Local anesthetic; Pain; Phoneutria spp.