Abstract
PurposeTo assess early renal pelvis opacification on postmyelography computed tomography (CT) as a marker for cerebrospinal fluid (CSF) loss in patients with spontaneous intracranial hypotension (SIH).MethodsThe SIH patients referred to our hospital between January 2012 and May 2018 were retrospectively reviewed and divided into 2 groups based on the presence of spinal longitudinal extrathecal CSF collection (SLEC): (1) SLEC(+) with, and (2) SLEC(−) without proof of SLEC on multimodal imaging. Non-SIH patients (n = 20) undergoing CT myelography served as controls. The renal pelvis density on postmyelography CT was measured in all patients. Mean difference in renal pelvis density between the groups was calculated.ResultsIn total, 111 SIH patients (mean age 48 ± 13 years; 60% female) were included, 71 (64%) SLEC(+) and 40 (36%) SLEC(−). The adjusted renal pelvis density in the SLEC(+), SLEC(−), and the non-SIH group was 108 Hounsfield unit (HU), 83 HU, and 32 HU, respectively, resulting in a significant difference between SLEC(+) vs. control group 1 (75 HU, p < 0.001), SLEC(−) vs. control group 1 (50 HU, p < 0.001), and a tendency for higher density in SLEC(+) than SLEC(−) (25 HU, p = 0.16).ConclusionIncreased renal pelvis opacification on postmyelography CT was observed in SIH patients, even in the absence of a CSF leak or a CSF venous fistula, when compared to non-SIH patients. Although the provenance of early renal opacification in SLEC (−) SIH patients remains unclear, our results suggest that it may be a surrogate for increased spinal CSF resorption via spinal arachnoid granulations and along spinal nerve sheaths occult to direct imaging.
Highlights
Spontaneous intracranial hypotension (SIH) has an estimated incidence of 2–5 per 100,000 inhabitants and is usually caused by a spinal cerebrospinal fluid (CSF) leak [1]
111 SIH patients matching the inclusion criteria were investigated at our center during the study period; 71 (64%) spinal longitudinal extrathecal CSF collection (SLEC)(+) patients with a spinal CSF leak and 40 (36%) SLEC(–) patients without proof of a CSF leak on multimodal spinal imaging (Table 1)
Patients investigated with computed tomography (CT) myelography to rule out spinal cord or nerve root compression served as control group 1, and patients who underwent an unenhanced CT scan of the lumbar spine served as reference but were not further evaluated in the absence of statistical abnormalities
Summary
Spontaneous intracranial hypotension (SIH) has an estimated incidence of 2–5 per 100,000 inhabitants and is usually caused by a spinal cerebrospinal fluid (CSF) leak [1]. In some patients with typical orthostatic headache who demonstrate characteristic findings on brain magnetic resonance imaging (MRI), multimodal spine imaging including non-enhanced MRI, intrathecal gadolinium-enhanced MRI, CT myelogram, or conventional myelogram may fail to reveal the underlying pathology. It is still unclear whether these represent false-negative spine imaging findings, especially given the challenging diagnosis of a CSFVF, or alternative pathomechanisms, such as hypercompliance of the thecal sac, increased CSF resorption, or decreased CSF secretion should be considered [1]
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