In the aftermath of recent outbreaks of emerging infectious diseases such as SARS and West Nile Virus, health departments in many states and provinces throughout North America implemented a syndromic surveillance system in hospital emergency departments (EDs) to assist with the early identification of public health emergencies. Coding schemes were developed for 12 distinct syndromes, and, on the basis of their clinical judgement, health-care providers were asked to choose the syndrome that best represented the patient's primary diagnosis. To track aberrations and detect excessive noise, a daily Syndrome to None ratio (SNR) was calculated. Alarms were generated when the SNR was significantly higher for the day in question compared with the recent past.
In August 2002, several EDs in the states of Tennessee, Arkansas and Nevada reported geographically localized high SNRs for Neurologic Syndrome. The index cases and resulting epidemiological investigations are described.
On Aug. 16, 2002, a 58-year-old previously healthy male was brought to the ED of St. Joseph's Hospital in Pine Bluff, Arkansas, by concerned relatives. They reported that the patient had recently developed movement tremors in the extremities, a gait disturbance and photophobia that prompted the patient to wear sunglasses indoors at all times. Physical exam also revealed a mild facial twitch affecting the left upper orbicularis oris, dysphonic speech and an exaggerated cremasteric reflex (grade 4), but no other abnormalities. The patient exhibited a remarkable lack of insight, reporting no symptoms other than insomnia and feeling, in his own words, "all shook up."
Electroencephalographic examination demonstrated...