Right Hand Weakness and Headache During Ascent to Mount Everest: A Case of Cerebral Venous Infarction

The Effect of High-Altitude Hypoxia on Neuropsychiatric Functions

Liu, Bo, Minlan Yuan, Mei Yang, Hongru Zhu, and Wei Zhang. The effect of high-altitude hypoxia on neuropsychiatric functions. High Alt Med Biol. 25:26-41, 2024. Background: In recent years, there has been a growing popularity in engaging in activities at high altitudes, such as hiking and work. However, these high-altitude environments pose risks of hypoxia, which can lead to various acute or chronic cerebral diseases. These conditions include common neurological diseases such as acute mountain sickness (AMS), high-altitude cerebral edema, and altitude-related cerebrovascular diseases, as well as psychiatric disorders such as anxiety, depression, and psychosis. However, reviews of altitude-related neuropsychiatric conditions and their potential mechanisms are rare. Methods: We conducted searches on PubMed and Google Scholar, exploring existing literature encompassing preclinical and clinical studies. Our aim was to summarize the prevalent neuropsychiatric diseases induced by altitude hypoxia, the potential pathophysiological mechanisms, as well as the available pharmacological and nonpharmacological strategies for prevention and intervention. Results: The development of altitude-related cerebral diseases may arise from various pathogenic processes, including neurovascular alterations associated with hypoxia, cytotoxic responses, activation of reactive oxygen species, and dysregulation of the expression of hypoxia inducible factor-1 and nuclear factor erythroid 2-related factor 2. Furthermore, the interplay between hypoxia-induced neurological and psychiatric changes is believed to play a role in the progression of brain damage. Conclusions: While there is some evidence pointing to pathophysiological changes in hypoxia-induced brain damage, the precise mechanisms responsible for neuropsychiatric alterations remain elusive. Currently, the range of prevention and intervention strategies available is primarily focused on addressing AMS, with a preference for prevention rather than treatment.

High-Altitude Exposure and Cerebral Venous Thrombosis: An Updated Systematic Review

Kharel, Sanjeev, Suraj Shrestha, Samriddha Raj Pant, Suman Acharya, Amit Sharma, Santosh Baniya, and Sanjeeb S. Bhandari. High-altitude exposure and cerebral venous thrombosis: an updated systematic review. High Alt Med Biol. 24:167-174, 2023. Background: High altitude (HA) may increase the risk of cerebral venous thrombosis (CVT). Differentiating it from other HA illnesses is crucial for prompt treatment and better outcomes. We aimed to summarize the clinical data, etiology, and risk factors of this poorly understood entity at an HA. Materials and Methods: A systematic literature search of various databases, including PubMed, Embase, and Google Scholar, was done using relevant keywords; cerebral venous thrombosis; HA, up to May 1, 2022. Results: A total of nine studies, including 75 cases of CVT at HA (3,000-8,848 m), with 66 males and 9 females, were included in this review. Headache and seizure were the most common clinical presentations. Smoking, drinking habits, and the use of oral contraceptive pills (OCP) were the most common risk factors for the development of CVT. Similarly, various underlying hypercoagulable states were also present among cases of CVT associated with HA exposure. Conclusion: Our review concludes that HA exposure can predispose individuals with risk factors such as preexisting hypercoagulable states, smoking, drinking habits, and use of OCP to an increased risk of CVT.

Secondary polycythaemia from chronic hypoxia is a risk for cerebral thrombosis: a case report

BACKGROUND

Secondary polycythemia is considered the usual complication of chronic hypoxia. It can theoretically increase the oxygen-carrying capacity, but this adaptive trait has a deleterious effect because the blood viscosity increases, which can induce significant morbidity and mortality, such as stroke and myocardial infarction.

CASE PRESENTATION

A 55-year-old man with a history of a congenitally small main pulmonary artery presented to the emergency department with sustained unsteady walking, dizziness and vertigo. Evaluation revealed elevated hemoglobin and superior posterior circulation cerebral artery thrombosis. The patient was treated with high flux inhalation of oxygen and anti-platelet aggregation.

CONCLUSIONS

The involvement of cerebral vessels has rarely been reported in chronic hypoxia cases. The present case is the first case of superior posterior circulation cerebral artery thrombosis due to chronic hypoxia in a patient with a congenitally small main pulmonary artery. This case demonstrates the importance of recognizing some chronic diseases that can lead to hypoxia and secondary polycythemia thereby leading to hypercoagulable state and subsequent thrombosis.