Neuro-Ophthalmologic Monitoring in the Management of Increased Intracranial Pressure From Leaking Arachnoid Cysts.

BACKGROUND: Intracranial arachnoid cysts are common incidental imaging findings. They may rarely rupture, leading to the development of subdural hygromas and high intracranial pressure (ICP). Neurosurgical intervention has been advocated in the past, but recent evidence indicates that most cases resolve spontaneously. The role of neuro-ophthalmologic monitoring in identifying the few cases that have persisting vision-threatening papilledema that justifies intervention has not been emphasized. METHODS: Retrospective review of 4 cases of leaking arachnoid cysts drawn from the files of the University of Michigan Medical Center (Michigan Medicine) between 2007 and 2018. RESULTS: In 1 case, surgery was avoidable as papilledema resolved over time despite lingering imaging features of mass effect. In 3 cases, papilledema persisted with the threat of permanent vision loss, prompting neurosurgical intervention. In one of those cases, the fluid collection was thinly but extensively spread across both hemispheres without brain shift; yet, papilledema was pronounced. Emergent evacuation led to rapid resolution of papilledema and encephalopathy, but with residual optic nerve damage. CONCLUSIONS: Because constitutional symptoms and even imaging are not always reliable indicators of high ICP in leaking arachnoid cysts, neuro-ophthalmologic monitoring of papilledema is valuable in identifying the cases when neurosurgical intervention is necessary.

CSF flow jet: novel CT myelogram finding of CSF leak through dural tear in traumatic pseudomeningocele.

Determining the exact location of dural violation after traumatic pre-ganglionic (avulsion) injury of the brachial plexus with associated progressively enlarging pseudomeningocele is critical for treatment, but current imaging by MR and CT myelogram remains inadequate as there are often only indirect imaging features. We present a case of a 25-year-old man with history of motorcycle accident and left brachial plexus injury, who was found to have an extensive anterior epidural CSF collection, resulting in the contralateral neurologic deficit. Surgical treatment relies upon the identification of the site of the dural violation. On dynamic CT myelogram images, a thin hyperdense line of contrast was seen, representing "CSF flow jet" extravasating into the pseudomeningocele. Subsequent laminectomy and foraminotomy revealed a left avulsed nerve root and a dural tear at the site localized on the CT myelogram. To our knowledge, this is the first case of using dynamic CT myelography to visualize "CSF flow jet," revealing the exact location of dural violation resulting in the expanding pseudomeningocele, providing crucial information for perioperative planning.

Orbital infantile hemangioma and rhabdomyosarcoma in children: differentiation using diffusion-weighted magnetic resonance imaging.

PURPOSE: To evaluate differences in magnetic resonance imaging (MRI) appearance between infantile hemangiomas and rhabdomyosarcomas of the orbit in pediatric patients using diffusion-weighted imaging. METHODS: A multicenter retrospective review of MRIs of pediatric patients with infantile hemangiomas and rhabdomyosarcomas of the orbit was performed. MRI examinations from a total of 21 patients with infantile hemangiomas and 12 patients with rhabdomyosarcomas of the orbit were independently reviewed by two subspecialty board-certified neuroradiologists masked to the diagnosis. A freehand region of interest was placed in the mass to obtain the mean apparent diffusion coefficient (ADC) value of the mass as well as within the medulla to obtain a ratio of the ADC mass to the medulla. A t test was used to compare mean ADC and ADC ratios between the two groups. Receiver operating characteristic analysis was performed to determine ADC value and ADC ratio thresholds for differentiation of infantile hemangioma and rhabdomyosarcoma. RESULTS: There was a statistically significant difference in the mean ADC value of infantile hemangiomas compared to rhabdomyosarcomas (1527 × 10-6 mm2/s vs 782 × 10-6 mm2/s; P = 0.0001) and the ADC ratio of the lesion to the medulla (1.77 vs 0.92; P = 0.0001). An ADC threshold of <1159 × 10-6 mm2/sec and an ADC ratio of <1.38 differentiated rhabdomyosarcoma from infantile hemangioma (sensitivity 100% and 100%; specificity 100% and 100%) with area under the curve of 1.0 and 1.0, respectively. CONCLUSIONS: In conjunction with conventional MRI sequences, ADC values obtained from diffusion-weighted MRI are useful to differentiate orbital infantile hemangiomas from rhabdomyosarcomas in pediatric patients.