Spontaneous intracranial hypotension: Detection of presumed site of spinal leak using T2 FIESTA MR imaging

Anisha S Tandon, Namita Sinha 
 Department of Radiology, St. John's Medical College Hospital, Bangalore, India

Correspondence Address:
Anisha S Tandon
Department of Radiology, St. John«SQ»s Medical College Hospital, Bangalore
India

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Sir,

Spontaneous intracranial hypotension (SIH) is thought to result from an occult cerebrospinal fluid (CSF) leak, [1] resulting in decreased CSF volume and pressure. Although the cranial and spinal magnetic resonance imaging (MRI) findings have been well documented, there has been only brief mention of predicting the site of leak on non-invasive MR imaging. We report the benefit of 3D Fast Imaging Employing Steady State Acquisition (3D FIESTA) MR imaging of the spine to document the possible site of CSF leak.

A 32-year-old man presented with one-month history of progressively worsening orthostatic headache, worsening as the day progressed. He also complained of dizziness, blurred vision, and nausea. There was no history of trauma or fever and the physical and neurological examination was normal. Intracranial MRI revealed diffuse thickening and enhancement of pachymeninges, bihemispheric subdural hygromas [Figure 1] and [Figure 2], sagging brainstem [Figure 1] and [Figure 3], and an increase in the mean height of pituitary [Figure 3]. Sagittal and axial T2 FIESTA of the cervicodorsal spine revealed an anterior extradural fluid collection [Figure 4] and [Figure 5] with prominent nerve root sleeves from C4-5 to C7-D1 levels, the latter most prominent on the left side at C5-6 level [Figure 6]. On the basis of these findings, we concluded that a cervicodorsal spinal CSF leak was responsible for the SIH and the possible site of leak was at the C5-6 level. He was subsequently treated with an autologous epidural blood patch injected in the lumbar region which failed to relieve his symptoms. In light of the spinal MR findings, a repeat epidural blood patch performed at the lower cervical level resulted in significant resolution of his symptoms.{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}

SIH is defined as a syndrome of reduced CSF pressure that occurs in the absence of dural puncture, surgery, or trauma. [1],[2],[3] The pathogenesis is usually considered to be an occult CSF leak through small defects in the meninges with a resultant decrease in CSF volume and pressure. [2],[3] The diagnostic intracranial imaging findings of SIH include subdural fluid collection, descent of the cerebellar tonsils, brainstem sagging, enlargement of the pituitary gland, and diffuse, intense pachymeningeal enhancement. [1],[2],[3] Spinal MRI abnormalities described in literature include distention of the epidural veins, epidural fluid collection, and abnormal visualization of the nerve root sleeves. [1],[2],[3],[4] In a case of SIH described by Rando and Fishman, [5] the patient had a leak at the C7-T1 level on radionuclide cisternography, which corresponded to MR findings of dilated nerve root sleeves, thought to be the site of CSF leakage. Our patient had classic cranial MR findings of SIH, with spinal MRI showing a large anterior cervicodorsal level epidural fluid collection with dilated nerve root sleeves from C4-5 to C7-D1 levels, maximally present at the left C5-6 level suggesting this region to be the site of leak. Relief of symptoms on treatment with epidural blood patch injected at the lower cervical level provided diagnostic confirmation of the possible site of leak. This patient highlights the importance of the 3D FIESTA sequence during spinal MR imaging to diagnose the site of CSF leak in cases of SIH. This non-invasive technique will alert the astute radiologist to subtle findings such as epidural fluid collections and distended nerve root sleeves which will enable predicting the level of spontaneous CSF leak.

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