Cerebral venous system and anatomical predisposition to high-altitude headache

The Traumatic Brain Injury Centre, St Mary's Hospital, Imperial College, London, W1 2NY
Annals of Neurology (Impact Factor: 9.98). 03/2013; 73(3). DOI: 10.1002/ana.23796
Source: PubMed


As inspired oxygen availability falls with ascent to altitude, some individuals develop high-altitude headache (HAH). We postulated that HAH results when hypoxia-associated increases in cerebral blood flow occur in the context of restricted venous drainage, and is worsened when cerebral compliance is reduced. We explored this hypothesis in 3 studies.

In high-altitude studies, retinal venous distension (RVD) was ophthalmoscopically assessed in 24 subjects (6 female) and sea-level cranial magnetic resonance imaging was performed in 12 subjects ascending to 5,300m. Correlation of headache burden (summed severity scores [0-4]≤24 hours from arrival at each altitude) with RVD, and with cerebral/cerebrospinal fluid (CSF)/venous compartment volumes, was sought. In a sea-level hypoxic study, 11 subjects underwent gadolinium-enhanced magnetic resonance venography before and during hypoxic challenge (fraction of inspired oxygen=0.11, 1 hour).

In the high-altitude studies, headache burden correlated with both RVD (Spearman rho=0.55, p=0.005) and with the degree of narrowing of 1 or both transverse venous sinuses (r=-0.56, p=0.03). It also related inversely to both the lateral+third ventricle summed volumes (Spearman rho=-0.5, p=0.05) and pericerebellar CSF volume (r=-0.56, p=0.03). In the hypoxic study, cerebral and retinal vein engorgement were correlated, and rose as the combined conduit score fell (a measure of venous outflow restriction; r=-0.66, p<0.05 and r=-0.75, p<0.05, respectively).

Arterial hypoxemia is associated with cerebral and retinal venous distension, whose magnitude correlates with HAH burden. Restriction in cerebral venous outflow is associated with retinal distension and HAH. Limitations in cerebral venous efferent flow may predispose to headache when hypoxia-related increases in cerebral arterial flow occur.

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Available from: Michael PW Grocott, Oct 08, 2015
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    • "Wilson first pointed out the analogy between the Space Adaptation Syndrome and the effects of altitude on the cerebral circulation, since they both lead to venous distension (Wilson et al., 2011). Wilson and colleagues suggest that venous distension plays an important role in high altitude headache (Wilson et al., 2013). Gabriel Willmann followed with a talk on the posterior part of the eye as a window on the brain in conditions of hypoxia (Willmann et al., 2014). "
    High altitude medicine & biology 05/2015; 16(3). DOI:10.1089/ham.2015.0046 · 1.28 Impact Factor
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    • "Notably, the prevalence of intracranial venous sinus stenosis at magnetic resonance venography (MRV) was found to be much higher than that previously expected in both IIHWOP and CM [7, 8]. Sinus stenosis has been recently reported to be highly prevalent also in other primary headaches [9–11]. Sinus stenosis is considered a reliable marker of idiopathic intracranial hypertension (IIH) with a sensitivity and specificity of 93 % [12]. "
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    ABSTRACT: To assess the prevalence and possible pathogenetic involvement of raised intracranial pressure in patients presenting with unresponsive chronic migraine (CM), we evaluated the intracranial opening pressure (OP) and clinical outcome of a single cerebrospinal fluid withdrawal by lumbar puncture in 44 consecutive patients diagnosed with unresponsive chronic/transformed migraine and evidence of sinus stenosis at magnetic resonance venography. The large majority of patients complained of daily or near-daily headache. Thirty-eight (86.4 %) had an OP >200 mmH2O. Lumbar puncture-induced normalization of intracranial pressure resulted in prompt remission of chronic pain in 34/44 patients (77.3 %); and an episodic pattern of headache was maintained for 2, 3 and 4 months in 24 (54.6 %), 20 (45.4 %) and 17 (38.6 %) patients, respectively. The medians of overall headache days/month and of disabling headache days/month significantly decreased (p < 0.0001) at each follow-up versus baseline. Despite the absence of papilledema, 31/44 (70.5 %) patients fulfilled the ICHD-II criteria for "Headache attributed to Intracranial Hypertension". Our findings indicate that most patients diagnosed with unresponsive CM in specialized headache clinics may present an increased intracranial pressure involved in the progression and refractoriness of pain. Moreover, a single lumbar puncture with cerebrospinal fluid withdrawal results in sustained remission of chronic pain in many cases. Prospective controlled studies are needed before this procedure can be translated into clinical practice. Nonetheless, we suggest that intracranial hypertension without papilledema should be considered in all patients with almost daily migraine pain, with evidence of sinus stenosis, and unresponsive to medical treatment referred to specialized headache clinics.
    Journal of Neurology 04/2014; 261(7). DOI:10.1007/s00415-014-7355-2 · 3.38 Impact Factor
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    • "A related hypothesis proposes that fluid redistribution to the intracellular space leading to astrocytic swelling underlies the development of symptomatic AMS [9]. More recently, it has been suggested that high altitude headache may relate to restricted venous drainage following the hypoxia-associated increase in cerebral blood flow at altitude [10]. "
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    ABSTRACT: Acute mountain sickness (AMS) is a common problem among visitors at high altitude, and may progress to life-threatening pulmonary and cerebral oedema in a minority of cases. International consensus defines AMS as a constellation of subjective, non-specific symptoms. Specifically, headache, sleep disturbance, fatigue and dizziness are given equal diagnostic weighting. Different pathophysiological mechanisms are now thought to underlie headache and sleep disturbance during acute exposure to high altitude. Hence, these symptoms may not belong together as a single syndrome. Using a novel visual analogue scale (VAS), we sought to undertake a systematic exploration of the symptomatology of AMS using an unbiased, data-driven approach originally designed for analysis of gene expression. Symptom scores were collected from 292 subjects during 1110 subject-days at altitudes between 3650 m and 5200 m on Apex expeditions to Bolivia and Kilimanjaro. Three distinct patterns of symptoms were consistently identified. Although fatigue is a ubiquitous finding, sleep disturbance and headache are each commonly reported without the other. The commonest pattern of symptoms was sleep disturbance and fatigue, with little or no headache. In subjects reporting severe headache, 40% did not report sleep disturbance. Sleep disturbance correlates poorly with other symptoms of AMS (Mean Spearman correlation 0.25). These results challenge the accepted paradigm that AMS is a single disease process and describe at least two distinct syndromes following acute ascent to high altitude. This approach to analysing symptom patterns has potential utility in other clinical syndromes.
    PLoS ONE 01/2014; 9(1):e81229. DOI:10.1371/journal.pone.0081229 · 3.23 Impact Factor
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