Abstract
Dear Sir We read with interest the article by Vieira et al. (1). This study shows a high frequency of idiopathic intracranial hypertension (IIH) without papilloedema (IIHWOP) in patients with chronic migraine (CM), a finding that confirms similar results obtained in previous studies (2–4).
The authors report on a consecutive series of patients with CM. Six patients out of 60 (10%) had increased cerebrospinal fluid opening pressure in the absence of papilloedema. One patient had a normal body mass index, whereas the remaining patients were obese or overweight. All patients had normal magnetic resonance imaging and magnetic resonance venography (MRV) of the brain. The authors suggest that obese patients with CM should undergo diagnostic lumbar puncture early in their management.
Our major criticism is the lack of information about the MRV technique used for exploring the disturbance of flow of transverse sinuses in CM patients. A correct MRV technique is needed to demonstrate the absence of bilateral transverse sinus stenosis (BTSS), a condition that has been reported to be associated with IIHWOP in the majority of patients with different forms of headache (2–4). On MRV, two-dimensional time-of-flight images and three-dimensional phase-contrast (3D-PC) images acquired with a velocity encoding (VENC) of 40 cm/s tend to bias the interpretation of flow signal toward normality, underestimating the disturbances of flow of transverse sinuses, whereas 3D-PC MRV set with the VENC to 15 cm/s represents the best non-invasive technical approach for visualizing BTSS in patients with IIH (5).
The frequency of IIHWOP is not known. Isolated headache is its most common symptom. Several authors have reported cases of IIHWOP in patients with chronic daily headache (including transformed migraine and chronic tension-type headache) (2, 3) when undergoing diagnostic lumbar puncture. Recently, it has also been reported that a number of individuals with migraine had IIHWOP (4). These findings highlight that to recognize headache attributable to IIH in the absence of papilloedema can be difficult, and patients with IIHWOP often have experienced extended delays in being diagnosed. Thus, the challenge is to find a tool for deciding which headache sufferers are candidates for lumbar puncture.
In the last few years, some authors have identified disturbances of venous flow on cerebral MRV in the majority of patients with IIH with or without papilloedema (2–4). Recently, it has been reported that 6.7% of individuals with migraine had BTSS on MRV, which in two-thirds of the cases was associated with IIHWOP (4). More recently, the same authors have demonstrated that a number of patients with chronic tension-type headache had BTSS associated with IIHWOP (3). At this time, BTSS as revealed by using 3D-PC MRV remains the best non-invasive predictor of IIHWOP in patients with chronic or recurrent headache.