Interpeduncular angle: A new parameter for assessing intracranial hypotension in fetuses with spinal dysraphism.

OBJECTIVE: To investigate the role of the interpeduncular angle (IPA) as a new indicator of intracranial hypotension in fetuses with open spinal dysraphism (SD). METHODS: Two groups of fetuses undergoing magnetic resonance imaging (MRI) examination were identified. The study group included fetuses with open SD (n = 21), while the control group included fetuses with a normal brain and spine (n = 43). Two observers retrospectively evaluated axial T2-weighted images of the brain and the IPA was identified and measured. Other features of the Chiari II malformation were also evaluated in the study group and correlated with the IPA. RESULTS: The average value (±SD) of the IPA for the study and control groups was 9.8° ± 18.5° and 60.2° ± 5.9°, respectively. The intergroup analysis of the IPA measurements revealed a statistically significant difference between the groups (p < 0.005). Brainstem slumping or cerebellar tonsillar descent, collapse of the fourth ventricle, and ventriculomegaly also had a significant correlation with a lower IPA (p = 0.001). CONCLUSION: Measuring the IPA may be a useful technique for assessing the degree of intracranial hypotension in fetuses with open SD. This technique can also detect less severe cases of prenatal intracranial hypotension, even before cerebellar tonsillar descent. The lower IPA in fetuses with open SD further supports the theory that cerebrospinal fluid leakage, and not traction, is the underlying cause of Chiari II malformation.

Application of IHS criteria to headache attributed to spontaneous intracranial hypotension in a large population.

We applied the recent International Headache Society (IHS) criteria for headache related to spontaneous intracranial hypotension (SIH) to 90 consecutive patients with a final diagnosis of SIH confirmed by cerebral magnetic resonance imaging with contrast. Orthostatic headache (developing within 2 h of standing or sitting up) was present in 67 patients (75%) but appeared within 15 min after standing or sitting-as required by point A of the criteria-in only 53 (59%). Forty-four (49%) patients did not satisfy point A, including 22 (24%) with non-orthostatic headache and 14 (16%) with headache developing >or= 15 min after standing or sitting up; 80 (89%) did not satisfy point D. Only three (3%) patients had headache fully satisfying the IHS criteria. These findings indicate that the current IHS criteria do not capture most patients with SIH-associated headache. Excluding the requirement for response to epidural blood patch (criterion D) and considering headaches appearing within 2 h of sitting or standing up would capture more patients.

Diagnostic criteria for spontaneous spinal CSF leaks and intracranial hypotension.

BACKGROUND AND PURPOSE: Comprehensive diagnostic criteria encompassing the varied clinical and radiographic manifestations of spontaneous intracranial hypotension are not available. Therefore, we propose a new set of diagnostic criteria. MATERIALS AND METHODS: The diagnostic criteria are based on results of brain and spine imaging, clinical manifestations, results of lumbar puncture, and response to epidural blood patching. The diagnostic criteria include criterion A, the demonstration of extrathecal CSF on spinal imaging. If criterion A is not met, criterion B, which is cranial MR imaging findings of spontaneous intracranial hypotension, follows, with at least one of the following: 1) low opening pressure, 2) spinal meningeal diverticulum, or 3) improvement of symptoms after epidural blood patch. If criteria A and B are not met, there is criterion C, the presence of all of the following or at least 2 of the following if typical orthostatic headaches are present: 1) low opening pressure, 2) spinal meningeal diverticulum, and 3) improvement of symptoms after epidural blood patch. These criteria were applied to a group of 107 consecutive patients evaluated for spontaneous spinal CSF leaks and intracranial hypotension. RESULTS: The diagnosis was confirmed in 94 patients, with use of criterion A in 78 patients, criterion B in 11 patients, and criterion C in 5 patients. CONCLUSIONS: A new diagnostic scheme is presented reflecting the wide spectrum of clinical and radiographic manifestations of spontaneous spinal CSF leaks and intracranial hypotension.

Spontaneous cerebrospinal fluid leaks: from intracranial hypotension to cerebrospinal fluid hypovolemia--evolution of a concept.

Intracranial hypotension causes orthostatic headaches and diffuse pachymeningeal gadolinium enhancement on magnetic resonance imaging with or without subdural fluid collections or imaging evidence of descent of the brain. A review of the literature and my experience and investigations in the past decade reveal a broadening clinical and imaging spectrum of the syndrome. Besides the classic clinical-imaging syndrome of orthostatic headaches, diffuse pachymeningeal gadolinium enhancement, and low cerebrospinal fluid (CSF) pressure, several modes of presentation are recognized, including (1) the typical clinical-imaging syndrome with CSF pressures consistently within normal limits, (2) absence of diffuse pachymeningeal gadolinium enhancement with presence of low CSF pressures and typical clinical manifestations, and (3) absence of headaches despite low CSF pressures and presence of diffuse pachymeningeal gadolinium enhancement. Furthermore, in some patients with headaches, the orthostatic headaches may evolve into lingering chronic daily headaches, although they may be more prominent in upright positions. What determines the various clinical and imaging features of this syndrome seems to be the loss of CSF volume as the independent variable, while other manifestations, including clinical features, CSF pressures, and imaging abnormalities, are variables dependent on the CSF volume. The term CSF hypovolemia is proposed for this syndrome because the term intracranial hypotension no longer seems adequate to embrace all the variations that have emerged.