METHODS: Twenty-one patients with LA and 21 age-matched controls were studied with CTP and assessed for their cognitive function. The subjects were classified into four groups: Group 1, with LA (n = 21); Group 2, without LA (n = 21); Group 3, with dementia (n = 7); Group 4, without dementia (n = 11). The mean cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) values were compared between groups 1 and 2, while mean CBF values were compared between groups 3 and 4.

RESULTS: Mean white matter CBF was considerably reduced in patients with LA in the frontal region by 42% (p = 0.000), basal ganglia by 37% (p = 0.000) and occipital region by 18% (p = 0.019). The mean white matter CBV was reduced in patients with LA in the frontal region by 36% (p = 0.000) and basal ganglia by 28% (p = 0.017). The mean white matter CBF was dramatically reduced in patients with dementia in the frontal region by 44% (p = 0.000), basal ganglia by 32% (p = 0.038) and occipital regions by 24% (p = 0.001).

METHODS: Clinical case records and laboratory investigations were reviewed. The case definition was: patients from the outbreak area, direct contact or in close proximity with pigs, clinical or CSF features of encephalitis.

RESULTS: The mean age was 38 years, 89% were male, 58% were ethnic Chinese, 78% were pig farm owners or hired workers. The mean incubation period was 10 days. The patients typically presented with nonspecific systemic symptoms of fever, headache, myalgia and sore throat. Seizures and focal neurological signs were seen in 16% and 5% respectively. In the more severe cases, this was followed by drowsiness and deteriorating consciousness requiring ventilation in 61%. Autonomic disturbances and myoclonic jerks were common features. The mortality was high at 41%. Systolic hypertension, tachycardia and high fever were associated with poor outcome. On the other hand, 40% recovered fully. As for the other 19%, the residual neurological signs were mostly mild.