Consensus document on neurosonological techniques in headaches.

Introduction: Neurosonology is a medical discipline that utilizes ultrasound techniques to study the nervous system, with its applications progressively increasing. The indications and methodology for applying these techniques in patients with headaches are not well defined, thus there is a need for a consensus guideline, based on expert opinion, to standardize their application in clinical practice.

Development: Experts in headaches and neurosonology, appointed by the headache study group of the Spanish Society of Neurology and the Spanish Society of Neurosonology, identified primary and secondary headaches where neurosonology has the greatest clinical application. A qualitative systematic review of the literature was conducted, based on available scientific evidence.

Conclusions: Cervical color duplex is considered a screening technique in patients with a high clinical suspicion of arterial dissection and may also be indicated for follow-up. Transcranial Doppler is a useful technique for evaluating the presence of vasospasm based on changes in mean flow velocity, and resistance and pulsatility indexes. Identification of the "halo sign" is highly specific for temporal arteritis. Measurement of the optic nerve sheath allows evaluation of the presence of intracranial hypertension. Finally, neurosonology may assist in occipital infiltration procedures or lumbar puncture and enables identification of changes in structures involved in the pathophysiology of migraine such as the periaqueductal gray matter and the raphe nuclei.