Cervical MRI Findings in Intracranial Hypotension

Intracranial hypotension is characterised by a fall in intracranial pressure presenting clinically with postural headache and cervical pain. The syndrome may arise after lumbar puncture, surgery, trauma, severe dehydration or spontaneously. We studied two patients with intracranial hypotension presenting hallmark intracranial MR features of the syndrome with different involvement of the cervical spine in terms of MR features and clinical presentation and course. MR imaging of the cervical and dorsal spine in both patients was carried out using T1, T2 and T2-FLAIR weighted sagittal spin echo sequences and T2 weighted axial turbo spin echo (TSE) sequences. In the first patient, MR disclosed an area of altered signal intensity within the cerebral canal in an extradural, anterior and lateral location both right and left, symmetrical with craniocaudal extension from C1 to D2. The area was strongly hyperintense in T2-FLAIR sequences compressing the anterolateral surface of the dura mater and was ascribed to an enlargement of the anterior vertebral venous plexus. MR examination four days later showed an almost complete resolution of the previous picture. In the second patient, MR imaging showed a fluid collection in the subdural space in the cervicodorsal spine in sagittal FLAIR and axial TSE images wth a hyperintense signal consistent with hygroma. Follow-up disclosed slow gradual resolution of the previous changes. The dilated epidural venous plexuses in the first patient could compensate the loss of CSF, as occurs intracranially where CSF volume is balanced with blood volume (Monro-Kellie's theory). The spinal hygroma evident in the second patient may have been a transudate secondary to meningeal hyperaemia. This hypothesis is supported by the raised proteins and cells found in the CSF and the meningeal enhancement after contrast administration. Intracranial hypotension is characterized not only by well-known changes in intracranial MR signal, but also by specific MR findings in the cervicodorsal spine. Knowledge of these MR features allows prompt recognition and adoption of the most suitable MR sequence with due assessment of the morphology of areas of altered signal intensity to disclose the pathogenesis.