Abstract
To the Editor,
We appreciate the interest of our dear colleagues M. Lisicki and L. Pessini (1) in our review of exertional headaches (2). As they point out, the internal jugular vein valve incompetence (IJVVI) has been the object of study as a possible trigger of conditions as varied as transient global amnesia (3), migraine (4), intracranial idiopathic hypertension (5) or exercise-induced headache (6). In relation to exercise-induced headache, it has been proposed that maneuvers such as the Valsalva could induce this type of headache by causing transient cerebral venous congestion. In this sense, the jugular vein valve constitutes the only valvular barrier between extra and intracranial venous circulation and therefore, its incompetence could contribute to increased venous pressure by generating a retrograde venous flow during the Valsalva maneuver (4).
As our colleagues indicate, case reports and some studies would support a higher prevalence of IJVVI in patients with primary exertional headache than in the general population, although the evidence obtained from these studies presents some weaknesses that question this association. Firstly, although a higher prevalence of IJVVI in individuals with exercise-induced primary headache (70%) versus controls (20%) was found in their study (6), their population sample was rather small (20 cases and 40 controls), and therefore this striking difference could be non-generalizable. In relation to this statement, doppler ultrasound studies carried out in larger population samples establish a prevalence of IJVVI of 90-95% in general population (7,8). On the other hand, a further study carried out in a population with transient global amnesia (9) showed that the existence of IJVVI did not correlate with changes in the cerebral venous circulation, which questions the causal hypothesis proposed in the exercise-induced headache. Finally, it is important to notice that the natural evolution of this headache is the spontaneous resolution of the condition in the vast majority of individuals by one year (10), which is not the expected evolution of a disease whose underlying cause is a permanent anatomical abnormality.
Therefore, in our opinion, more studies are necessary to confirm or rule out the existence of an association between IJVVI and exercise-induced headache, before both transferring to routine clinical practice the performance of imaging tests to rule out IJJVVI and considering a specific code in the International Classification of Headache Disorders.
