Listeria monocytogenes brain abscesses presenting as contiguous, tubular rim-enhancing lesions on Magnetic Resonance Imaging: Case series and literature review.

Listeriosis has more than a 50% mortality when the central nervous system is involved, necessitating rapid diagnosis and treatment. We present four patients with brain abscesses in the setting of diagnosed neurolisteriosis, all of which demonstrated an odd presentation of multiple small, contiguous tubular lesions with rim enhancement on magnetic resonance imaging. Our review of published cases of neurolisteriosis suggests that this may be a useful pattern to identify neurolisteriosis abscesses, allowing earlier detection and therapy.

Imaging-Based Features of Headaches in Chiari Malformation Type I.

BACKGROUND: Suboccipital cough-induced headaches are considered a hallmark symptom of Chiari malformation type I (CMI). However, non--Valsalva-related suboccipital headaches and headaches in other locations are also common in CMI. The diagnostic significance and the underlying factors associated with these different headaches types are not well understood. OBJECTIVE: To compare cranial morphology and hydrodynamics in 3 types of headaches in CMI to better understand the pathophysiological basis for the different headache characteristics. METHODS: Twenty-two cranial physiological and morphological measures were obtained with specialized magnetic resonance imaging scans from 63 symptomatic pretreated CMI patients, 40 with suboccipital headaches induced by Valsalva maneuvers (34 women; age, 36 ± 10 years), 15 with non--Valsalva-related suboccipital headaches (10 women; age, 33 ± 9 years), 8 with nonsuboccipital non--Valsalva-induced headaches (8 women; age, 39 ± 13 years), and 37 control subjects (24 women; age, 36 ± 12 years). Group differences were identified with the use of the 2-tailed Student t test. RESULTS: Posterior cranial fossa markers of CMI were similar among the 3 headache subtypes. However, the Valsalva-related suboccipital headaches cohort demonstrated a significantly lower intracranial compliance index than the non--Valsalva-related suboccipital headaches cohort (7.5 ± 3.4 vs 10.9 ± 4.9), lower intracranial volume change during the cardiac cycle (0.48 ± 0.19 vs 0.61 ± 0.16 mL), and higher magnetic resonance imaging--derived intracranial pressure (11.1 ± 4.3 vs 7.7 ± 2.8 mm Hg; P = .02). The Valsalva-related suboccipital headaches cohort had smaller intracranial and lateral ventricular volumes compared with the healthy cohort. The non--Valsalva-related suboccipital headaches cohort had reduced venous drainage through the jugular veins. CONCLUSION: Valsalva-induced worsening of occipital headaches appears to be related to a small intracranial volume rather than the smaller posterior cranial fossa. This explains the reduced intracranial compliance and corresponding higher pressure measured in CMI patients with headaches affected by Valsalva maneuvers.

Magnetic resonance imaging measures of posterior cranial fossa morphology and cerebrospinal fluid physiology in Chiari malformation type I.

BACKGROUND: It has been well documented that, along with tonsillar herniation, Chiari Malformation Type I (CMI) is associated with smaller posterior cranial fossa (PCF) and altered cerebrospinal fluid (CSF) flow and tissue motion in the craniocervical junction. OBJECTIVE: This study assesses the relationship between PCF volumetry and CSF and tissue dynamics toward a combined imaging-based morphological-physiological characterization of CMI. Multivariate analysis is used to identify the subset of parameters that best discriminates CMI from a healthy cohort. METHODS: Eleven length and volumetric measures of PCF, including crowdedness and 4th ventricle volume, 4 measures of CSF and cord motion in the craniocervical junction, and 5 global intracranial measures, including intracranial compliance and pressure, were measured by magnetic resonance imaging (MRI) in 36 symptomatic CMI subjects (28 female, 37 ± 11 years) and 37 control subjects (24 female, 36 ± 12 years). The CMI group was further divided based on symptomatology into "typical" and "atypical" subgroups. RESULTS: Ten of the 20 morphologic and physiologic measures were significantly different between the CMI and the control cohorts. These parameters also had less variability and stronger significance in the typical CMI compared with the atypical. The measures with the most significance were clival and supraocciput lengths, PCF crowdedness, normalized PCF volume, 4th ventricle volume, maximal cord displacement (P < .001), and MR measure of intracranial pressure (P = .007). Multivariate testing identified cord displacement, PCF crowdedness, and normalized PCF as the strongest discriminator subset between CMI and controls. MR measure of intracranial pressure was higher in the typical CMI cohort compared with the atypical. CONCLUSION: The identified 10 complementing morphological and physiological measures provide a more complete and symptomatology-relevant characterization of CMI than tonsillar herniation alone.