Cerebral Venous Sinus Thrombosis during Everest Expedition: A Case Report and Review of the Literature

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.

The Influence of Environmental Hypoxia on Hemostasis—A Systematic Review

Humans have been ascending to high altitudes for centuries, with a growing number of professional- and leisure-related sojourns occurring in this millennium. A multitude of scientific reports on hemostatic disorders at high altitude suggest that hypoxia is an independent risk factor. However, no systematic analysis of the influence of environmental hypoxia on coagulation, fibrinolysis and platelet function has been performed. To fill this gap, we performed a systematic literature review, including only the data of healthy persons obtained during altitude exposure (<60 days). The results were stratified by the degree of hypoxia and sub-categorized into active and passive ascents and sojourns. Twenty-one studies including 501 participants were included in the final analysis. Since only one study provided relevant data, no conclusions regarding moderate altitudes (1,500–2,500 m) could be drawn. At high altitude (2,500–5,400 m), only small pathophysiological changes were seen, with a possible impact of increasing exercise loads. Elevated thrombin generation seems to be balanced by decreased platelet activation. Viscoelastic methods do not support increased thrombogenicity, with fibrinolysis being unaffected by high altitude. At extreme altitude (5,400–8,850 m), the limited data showed activation of coagulation in parallel with stimulation of fibrinolysis. Furthermore, multiple confounding variables at altitude, like training status, exercise load, fluid status and mental stress, prevent definitive conclusions being drawn on the impact of hypoxia on hemostasis. Thus, we cannot support the hypothesis that hypoxia triggers hypercoagulability and increases the risk of thromboembolic disorders, at least in healthy sojourners.

Relevance of Geographical and Biochemical Factors in Causation of Cerebral Venous Sinus Thrombosis: An Observational Analytical Study

Objectives

There is a higher prevalence of cerebral venous sinus thrombosis (CVST) in more recent times, owing to increased awareness, clinical diagnostic skills, and advancements in neuroimaging modalities. This study aimed to identify and characterize the geographical, clinical, and etiological profiles of patients with CVST that may be relevant to planning appropriate diagnostic and therapeutic strategies to improve functional recovery.

Methods and Results

A retrospective observational study was carried out at a tertiary care hospital between March 2014 and October 2018. The demographics and clinical profile of the hospitalized patients were extracted from the Medical Record Division. Choropleth maps were created to present the geographic distribution of the patients with CVST admitted to our hospital. A total of 145 patients with CVST were included in the study. Etiological factors revealed striking abnormalities in red blood cells counts and serum homocysteine. Analyzing the geographical distribution of the patients with CVST showed most of the patients hailed from Central Karnataka Plateau 106 (73%). Polycythemia was most commonly seen in patients residing in the Central Karnataka Plateau 21 (62%).

Conclusion

It is inferred that large scale community-based studies to identify a genetic abnormality like a mutant erythropoietin gene should be undertaken to plan effective diagnostic, therapeutic, and preventive measures.

Recommendations for traveling to altitude with neurological disorders

BACKGROUND

Several neurological conditions might worsen with the exposure to high altitude (HA). The aim of this review was to summarize the available knowledge on the neurological HA illnesses and the risk for people with neurological disorders to attend HA locations.

METHODS

A search of literature was conducted for several neurological disorders in PubMed and other databases since 1970. The neurological conditions searched were migraine, different cerebrovascular disease, intracranial space occupying mass, multiple sclerosis, peripheral neuropathies, neuromuscular disorders, epileptic seizures, delirium, dementia, and Parkinson's disease (PD).

RESULTS

Attempts were made to classify the risk posed by each condition and to provide recommendations regarding medical evaluation and advice for or against traveling to altitude. Individual cases should be advised after careful examination and risk evaluation performed either in an outpatient mountain medicine service or by a physician with knowledge of HA risks. Preliminary diagnostic methods and anticipation of neurological complications are needed.

CONCLUSIONS

Our recommendations suggest absolute contraindications to HA exposure for the following neurological conditions: (1) Unstable conditions-such as recent strokes, (2) Diabetic neuropathy, (3) Transient ischemic attack in the last month, (4) Brain tumors, and 5. Neuromuscular disorders with a decrease of forced vital capacity >60%. We consider the following relative contraindications where decision has to be made case by case: (1) Epilepsy based on recurrence of seizure and stabilization with the therapy, (2) PD (± obstructive sleep apnea syndrome-OSAS), (3) Mild Cognitive Impairment (± OSAS), and (4) Patent foramen ovale and migraine have to be considered risk factors for acute mountain sickness.

Bilateral superior ophthalmic vein thrombosis associated with high altitude

We report a case of a 47-year-old female who experienced periorbital swelling while descending from a Himalayan mountain climb and was found to have bilateral superior ophthalmic vein thromboses (SOVT). Infectious, autoimmune, and hypercoagulability work-up were negative with no cavernous sinus involvement. Symptoms resolved upon initiation of anticoagulation and oral steroids. SOVT is a rare but serious condition and has a risk of extending into the cavernous sinus if not treated early. Although infection is the most common etiology, venous thrombosis can be precipitated under high altitude and low oxygen pressure environments. We present a case of superior ophthalmic vein thrombosis associated with high-altitude conditions.

Cerebral Venous Thrombosis at High Altitude: A Retrospective Cohort of Twenty-one Consecutive Patients

Background 

Cerebral venous thrombosis (CVT) is a rare cerebrovascular disorder, comprising <1% of all strokes. The incidence of CVT is higher in females but a small number of cases suggest that men have a higher risk for CVT in high elevation. The aim of this retrospective cohort study is to investigate this gender-related relationship and to describe the baseline characteristics and treatment outcomes of patients who suffered CVT at high altitude in eastern Nepal.

Methods 

We conducted a retrospective analysis of 21 consecutive patients with CVT at a tertiary care center in Nepal from July 2017 to January 2018. Clinical data, radiologic characteristics, therapeutic strategies, and outcomes were analyzed. The Glasgow Outcome Scale (GOS) at discharge was reported for each patient. 

Result

The study cohort comprised 21 patients (76% males) with a mean of 56 years. Medical comorbidities included hypertension (76%) and diabetes mellitus (57%). All patients received low-molecular-weight heparin therapy (LMWH). Eight patients (38%) underwent decompressive craniectomy while the remaining 13 (62%) were treated with medical therapy alone. The GOS at discharge was 5 in 57%, 2-4 in 33%, and 1 in 10%.

Conclusion 

In our series, men were found to have a higher risk for CVT at high altitude. The reversal in the gender ratio could be related to elevation, but could also be confounded by alcoholism. Increasingly sophisticated imaging techniques, such as computed tomography venography (CTV) and magnetic resonance venography (MRV), have facilitated the diagnosis of CVT. LMWH is a safe and easily accessible treatment option, especially in developing countries. Further studies are needed to assess the incidence and prevalence of CVT in the developing world, to establish the gender-related trends.