Cervical MR imaging in postural headache: MR signs and pathophysiological implications

BACKGROUND AND PURPOSE: Postural headache most often occurs after lumbar pu ncture as post-lumbar puncture headache (PLPH) or, rarely, spontaneously as spontaneous intracranial hypotension headache (SIHH). In this prospective study, we used spinal MR imaging to determine the findings that would assis t in the diagnosis of PLPH and SIHH and that would further our pathophysiol ogical understanding of postural headache. METHODS: The study group consisted of 15 healthy volunteers and 20 patients with postural headache: nine with SIHH and 11 with PLPH. The craniocervica l junction and the cervical spine were studied using T2-weighted fast spin- echo and TI-weighted spin-echo sequences in the axial and sagittal planes. Follow-up studies were performed in 13 patients. RESULTS: Dilatation of the anterior internal vertebral venous plexus was th e most constant finding, present in 17 (85%) of 20 patients with postural h eadache. Spinal hygromas, whose location as subdural or epidural could not be exactly determined, were present in 14 patients (70%). A focal fluid col lection was detected in the retrospinal region at the C1-C2 level in six pa tients with SIHH and in four patients with PLPH (50%). Tonsillar descent wa s detected in only one patient, and subtentorial hygroma in five patients. No abnormalities were found in the volunteers. CONCLUSION. The MR signs of dilatation of the venous plexus, presence of sp inal hygromas, and presence of retrospinal fluid collections can help to es tablish the diagnosis of intracranial hypotension. They are probably the re sult of decreased CSF volume, with the retrospinal fluid collections being a transudate from the venous plexus rather than frank extravasation. Resolu tion of these signs parallels resolution of the headache.