Stroke in Young at High Altitude: A Case-Control Study from India.
Authors: Kotwal Jyoti , Hemat Fellowship , Chopra G. S. , Mukherjee J. D. , Singh K. K. , Kotwal A. , Epidem Fellowship , Bhardwaj J. R. 
Published: October 2019

Abstract
There is limited knowledge about stroke in young individuals in high altitude (HA). We present the clinico-hematological profile of 21 cases of stroke in young seen between July 2000 to March 2002, at a hospital at a height of 3250 meters above mean sea level. All of them were investigated at the time of occurrence of the event with detailed hematological, neurological, biochemical, radiological, carotid doppler, neuroimaging and vasculitic workup. The thrombophilia work up was done at least 12 weeks after the occurrence of stroke, consequent to stopping anticoagulant therapy. Their mean age was 32.6 years (SD 7.9) and they were low landers staying at HA for 3 to 24 months (mean 8 months). 13 (62 percent) presented at heights between 3000–4000 meters and rest (38 percent) were evacuated from heights greater then 4000 meters. 14 (66.7 percent) had ischemic stroke, 2 (9.5 percent) had intracranial hemorrhage, 3 (14.3 percent) had TIA (transient ischemic attack)/RIND (reversible ischemic neurological deficiency) and 2 (9.5 percent) cerebro venous thrombosis. CT scan showed multiple cerebral infarcts in 10 (48 percent) cases. Initial presentation was considered to be high altitude cerebral edema (HACO) in all the cases. 2 (9.5 percent) presented with seizures and 1 (5 percent) had additionally left axillary artery thrombosis. 3 (14.3 percent) had primary hypertension, 2 were smokers, 2 had loose motions and 2-forced inactivity prior to event. All cases recovered adequate activities of daily living (ADL). Hyper homocysteinemia was found in 3 patients, protein C and S deficiency in 1 each respectively. Pro coagulant factors were identified in 5 cases (24 percent) as compared to stroke in young in low altitude where we earlier found these factors in 30%. The increased incidence of cerebral thrombosis at HA thus shows that long-term stay at HA is associated with a higher risk of stroke. Table shows the results of comparison of values of Hemoglobin, platelet count, BTG, PF4, fibrinogen and PAI-1, between patients at the time of stroke and controls matched for age, sex and duration of stay at HA. Platelet counts showed a significant fall in patients probably due to utilization in the acute thrombus. Platelet activation factors, BTG, PF4, fibrinogen and PAI-1 were significantly higher in the patients as compared to controls. Thereby showing that in patients who develop thrombosis at HA the milieu is pro thrombotic. Asymptomatic individuals who have protein C and S deficiency and hyper homocysteinemia may get cerebral thrombosis when inducted to HA.
Comparison Of Hematological Tests Between Cases Of Stroke And Matched Controls
Tests done Cases Mean (SD) Controls Mean (SD) P Value * Not Statistically Significant; ¤ Statistically Significant Hemoglobin (gm/dl) 16.0 (1.09) 16.5 (0.59) 0.071 * Platelet Count (x10 ³/mm³) 255 (53.89) 350.75 (27.91) 0.000¤ Beta Thromboglobulin (IU/ml) 59.45 (11.23) 47.25 (5.64) 0.000¤ Platelet Factor 4 (IU/ml) 18.64 (4.16) 13.71 (3.39) 0.000¤ Fibrinogen (mg/dl) 456.19 (83.65) 395.25 (50.75) 0.013¤ PAI-1 (ng/ml) 50.42 (7.38) 39.32 (6.14) 0.000¤