The Interpeduncular Angle: A Practical and Objective Marker for the Detection and Diagnosis of Intracranial Hypotension on Brain MRI

A Severe Case of Spontaneous Intracranial Hypotension in an Adult Asian Male Improved With Trendelenburg Positioning: A Case Report

Non-traumatic bilateral acute subdural hematomas are a rare occurrence. Etiologies typically include, but are not limited to, cortical artery bleeding, vascular lesions, coagulopathies, and spontaneous intracranial hypotension. We report a case of a 45-year-old Korean male with no known co-morbid illnesses nor history of head or neck trauma, who came to the emergency department due to a 10-day history of dizziness and head heaviness, followed by disorientation and drowsiness. The patient was diagnosed with bilateral acute subdural hematoma; hence, a bilateral posterior parietal craniotomy with evacuation of hematoma was performed. Neurologic status initially improved remarkably; however, during rehabilitation, there was recurrence of acute bilateral subdural hematoma requiring repeat surgical evacuation. There was no clinical improvement after the repeat surgery, and his condition further deteriorated in the neurosciences critical care unit showing signs of rostrocaudal deterioration at the level of diencephalon. A plain cranial CT scan was performed, which showed central herniation and "brain sagging." A diagnosis of spontaneous intracranial hypotension was considered; thus, the patient was managed by positioning him in the Trendelenburg position alternating with flat position on the bed. A search for the cerebrospinal fluid leak was commenced by performing a whole spine MRI constructive interference in steady state (CISS) protocol, which showed a longitudinal spinal anterior epidural cerebrospinal fluid leak from spinal level C2 to T1. Radionuclide cisternography did not provide definitive scintigraphic evidence of a leak. The patient gradually improved and was eventually transferred out of the neurosciences critical care unit. After days of rehabilitation in the hospital, the patient was discharged ambulatory with minimal support.

Normal measurements of brainstem and related structures for all ages: An MRI-based morphometric study

Background

Knowledge of the normal size of the brain stem and certain related structures play an important role in diagnosis of aging and neurodegenerative conditions affecting the brain. There is no well-established normative data for development and age-related changes pertaining to the brain stem and related structures in the Indian context. The objective of this study was to assess various linear and angle measurements of the brain stem, cerebral peduncles, middle cerebellar peduncles, and proximal cervical cord for all ages in patients who have undergone MRI brain for unrelated pathologies.

Methods

A record-based retrospective cross-sectional and analytical study. T1WI axial and sagittal images were studied for the following variables: Cerebral peduncle transverse thickness, Interpeduncular angle, Middle cerebellar peduncle transverse thickness, Ventral midbrain anteroposterior thickness, Midbrain height, Mamillopontine distance (MPD), Pontomesencephalic angle (PMA), Pons anteroposterior thickness, Medulla anteroposterior thickness and Spinal cord anteroposterior diameter.

Results

Significant differences (p = 0.001) were observed in nearly all the variables among various age groups. Males demonstrated significantly higher mean values (at 5% level of significance) for a majority of the variables. Most of the variables measured, e.g. Cerebral peduncle, Middle cerebellar peduncle, Ventral midbrain thickness, Midbrain height, Pons, Medulla, and Spinal Cord diameter, showed a steady and sharp increase in values from infancy and reached maximum values during the third decade, followed by a variable degree of decline in values.

Conclusion

Magnetic Resonance Imaging (MRI) morphometry of brainstem and related structures is easily doable and is also reproducible. Present study lays down normative data for the brainstem and certain related structures for all ages, which can be referred to in day-to-day practice.

Neuroimaging Pearls from the MDS Congress Video Challenge. Part 2: Acquired Disorders

The MDS Video Challenge continues to be the one of most widely attended sessions at the International Congress. Although the primary focus of this event is the presentation of complex and challenging cases through videos, a number of cases over the years have also presented an unusual or important neuroimaging finding related to the case. We reviewed the previous Video Challenge cases and present here a selection of those cases which incorporated such imaging findings. We have compiled these "imaging pearls" into two anthologies. The first focuses on pearls where the underlying diagnosis was a genetic condition. This second anthology focuses on imaging pearls in cases where the underlying condition was acquired. For each case we present brief clinical details along with neuroimaging findings, the characteristic imaging findings of that disorder and, finally, the differential diagnosis for the imaging findings seen.

Spontaneous intracranial hypotension: the role of radiology in diagnosis and management

Spontaneous intracranial hypotension (SIH) is a condition that results from leakage of cerebrospinal fluid (CSF) from the spine, and which typically presents with debilitating orthostatic headache, but can be associated with a wide range of other symptoms. The causes of spontaneous CSF leaks that lead to SIH include dural tears, leaking meningeal diverticula, and CSF-venous fistulas. Imaging plays a central role in the initial diagnosis of SIH and in its subsequent investigation and management. This article reviews the typical neuroimaging manifestations of SIH and discusses the utility of different myelographic techniques for localising spinal CSF leaks as well as the role of image-guided treatment.

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.

Magnetic resonance parkinsonism indices and interpeduncular angle in idiopathic normal pressure hydrocephalus and progressive supranuclear palsy

Purpose

The clinical presentation of idiopathic normal pressure hydrocephalus (iNPH) may overlap with progressive supranuclear palsy (PSP). The Magnetic Resonance Parkinsonism Index (MRPI), MRPI 2.0, and the interpeduncular angle (IPA) have been investigated to differentiate PSP from healthy controls (HC) and other parkinsonisms. We aimed to assess equivalences and differences in MRPI, MRPI 2.0, and IPA in iNPH, PSP, and HC groups.

Methods

We retrospectively recruited 99 subjects (30 iNPH, 32 PSP, 37 HC) from two institutions. MRI exams, acquired on either 1.5 T or 3 T scanners, included 3D T1-weighted images to measure MRPI, MRPI 2.0, and IPA. Inter- and intra-rater reliability was investigated with the intra-class correlation coefficient (ICC), and the two one-sided t tests (TOST) procedure was used to assess these markers in iNPH, PSP, and HC.

Results

For all the three measures, intra-rater and inter-rater ICC were excellent (range = 0.91–0.93).

In the comparison of iNPH and PSP with HC, differences for MRPI and MRPI 2.0 (p < 0.01 in all cases) and no equivalence (p = 1.00 in all cases) were found at TOST. iNPH and PSP MRPI showed no difference (p = 0.06) and no equivalence (p = 0.08). MRPI 2.0 was not equivalent (p = 0.06) and not different (p = 0.09) in the same two populations. PSP and HC IPA proved equivalent (p < 0.01) while iNPH IPA was different (p < 0.01) and not equivalent (p = 0.96 and 0.82) from both PSP and HC.

Conclusion

MRPI and MRPI 2.0 significantly overlap in iNPH and PSP, with risk of misdiagnosis, and for this reason may not be helpful in the differential diagnosis.

Electronic supplementary material

The online version of this article (10.1007/s00234-020-02500-1) contains supplementary material, which is available to authorized users.