Stroke at high altitude: Indian experience.

Stroke is a common medical emergency. There is limited knowledge about stroke at high altitude. We present the clinical profile of 30 cases of stroke at high altitude seen at our center between November 1998 to July 2000. A detailed neurological and systemic examination was carried out. Cases were investigated with blood counts, lipid profile, cardiac evaluation, and CT scan/MRI. Coagulation parameters were studied in some cases. Strokes formed 13.7/1000 of hospital admissions from high altitude area, compared to 1.05/1000 in nonhigh altitude area. All our cases from high altitude area were males (serving soldiers of armed forces). Their mean high altitude stay was 10.2 months, and they were all located at heights greater than 4270 m. Age ranged from 22 to 48 years (mean 33.4 yr). Except for smoking (in four cases), they had no preexisting risk factors. Twenty-two cases were of ischemic stroke, 2 of intracerebral hemorrhage, 4 of TIA/RIND (transient ischemic attack/reversible ischemic neurological deficit), and 2 had cerebral venous thrombosis. Out of 30 cases, 28 were of "stroke in young" (<45 yr) and were compared with cases in the same age group from nonhigh altitude areas. Polycythemia with Hb ranging from 16.2 to 22 g.dL(-1) was seen in 21 of these 28 cases (75%). Protein C and S deficiency was found in 1 case in each group. CT scan showed massive infarcts involving at least 50% of one cerebral hemisphere in 12 cases. Multiple infarcts were seen in one case.

CONCLUSIONS

Long-term stay at high altitude is associated with higher risk of stroke. Although all types of stroke were seen, ischemic stroke was the commonest. Massive infarcts were common. Polycythemia was an important risk factor.