Abstract

Global ‘hypoxic brain injury’ commonly presents typically after hypoperfusion, although true hypoxia may be absent. MRI is used to confirm clinical diagnosis is sought. However, a potentially different pattern of brain involvement may exist in the context of anaphylactic reactions. A previous well man (48) suddenly informed his co-worker of a wasp sting and rapidly lost consciousness. Paramedics were sought who arrived to find him in status epilepticus. He'd suffered a wasp sting 3 weeks earlier. Seizures came under control with standard anti-epileptic drugs and general anaesthesia on ITU. Acute brain CT (day 0) showed subtle reduced attenuation of the basal ganglia, progressing over 3 days to generalised cerebral sulcal effacement and symmetrical reduced attenuation of basal ganglia and much of the anterior circulation cortex. MRI (day 4) showed restricted diffusion, consistent with cytotoxic oedema, matching CT regions of low attenuation. Structures supplied by the posterior circulation, the limbic system, the insular and the medial perirolandic cortices were notably spared. Brain CT at 4 weeks showed atrophy in a similar distribution. Retrospectively although initial blood gases did not suggest severe hypoxia (base excess −2.6, pH 7.36) intubation was difficult probably reflecting laryngospasm. Ventilation indices did not suggest airflow limitation. Allergic rash was never observed. No specific measures were required to maintain blood pressure Raised blood tryptase released from mast cells supported diagnosis of significant anaphylaxis. Seizures were contained and ventilatory support withdrawn but he remains in a vegetative state. Although seizures may have contributed to or accentuated cortical MRI changes, this pattern of cytotoxic oedema has been previously described in anaphylactic shock (a Hoffmann J et al).