Defining the typical characteristics of orthostatic headache in patients with spontaneous intracranial hypotension.

Background: Orthostatic headache (OH) is a common feature of various conditions, including spontaneous intracranial hypotension (SIH), but no precise definition currently exists outlining the typical OH characteristics. This ambiguity risks misdiagnosis with unnecessary investigations and delay in institution of treatment. The present study aimed to carry out structured phenotyping of OH in patients with SIH with the aim of outlining its typical characteristics.

Methods: Eligible patients with clinico-radiological confirmed SIH underwent a structured interview, after which a specialist interest group utilised the modified Delphi process to analyse the data and achieve consensus on defining the typical characteristics of OH in SIH.

Results: In total, 137 patients were recruited. OH was present in 75.9%. Typical OH characteristics in SIH were defined as having a baseline severity (lying flat) on waking up of ≤3 (0-10, verbal response scale), headache onset-time of ≤4.5 h on becoming upright, time to peak severity of ≤7.5 h and an offset to baseline severity within 1.5 h of recumbency. Intra-individual consistency in the onset and offset-time was deemed a necessary characteristic.

Conclusions: Defining typical OH characteristics has the potential of enhancing SIH diagnostics and management, at the same time as minimising unwarranted invasive procedures.