In the scientific literature, syringohydromyelia has only rarely been reported in association with spontaneous intracranial hypotension. Management of the syringohydromyelia in these patients has heretofore involved relatively invasive surgical procedures. The authors report the first case of syringohydromyelia in the setting of intracranial hypotension successfully treated with CT-guided epidural blood patches. This case is important in that it represents a potential minimally invasive treatment strategy. Furthermore, the case also highlights the need to consider spontaneous intracranial hypotension when clinically appropriate as a cause of syrinx in patients with cerebellar tonsillar ectopia, in whom the lesion might otherwise be misclassified as a Chiari I malformation. Finally, the responses to the various attempted treatments offer insight into the pathophysiology of this syringohydromyelia, which may differ from classical models of syrinx formation.
Peter G. Kranz, Ronald J. Viola, and Linda Gray
Frank Mihlon, Peter G. Kranz, Andreia Roxana Gafton, and Linda Gray
Cerebrospinal fluid leaks due to unrecognized durotomy during spinal surgery are often managed with a second surgery for dural closure. CT-guided percutaneous patching targeted to the dural defect offers an alternative to surgery since it can be performed in a minimally invasive fashion without the need for general anesthesia. This case series describes the authors' experience using targeted CT-guided percutaneous patching to repair incidental durotomies incurred during spinal surgery.
This investigation is a retrospective case series involving patients who underwent CT-guided percutaneous patching of surgical incidental durotomies and were referred between January 2007 and June 2013. Their presenting clinical history, myelographic findings, and clinical outcomes, including the need for eventual surgical duraplasty, were reviewed.
Nine cases were identified, including 7 durotomies incurred during lumbar discectomy, one due to a medial transpedicular screw breach, and one incurred during vertebrectomy for spinal osteosarcoma. All patients who had favorable outcomes with percutaneous intervention alone had 2 common features: dural defect of 4 mm or smaller and absence of a pseudomeningocele. Patients with CSF leaks complicated by pseudomeningocele and those with a dural defect of 6 mm or more all required eventual surgical management.
The authors' results suggest that findings on CT myelography may help predict which patients with postsurgical durotomy can be treated with percutaneous intervention. In particular, CT-guided patching may be more likely to be successful in those patients with dural defects of less than 5 mm and without pseudomeningocele. In patients with larger dural defects or pseudomeningoceles, percutaneous blood patching alone is unlikely to be successful.
Jessica L. Houk, Timothy J. Amrhein, Linda Gray, Michael D. Malinzak, and Peter G. Kranz
Chiari malformation type 1 (CM-1) and spontaneous intracranial hypotension (SIH) are causes of headache in which cerebellar tonsillar ectopia (TE) may be present. An accurate method for differentiating these conditions on imaging is needed to avoid diagnostic confusion. Here, the authors sought to determine whether objective measurements of midbrain morphology could distinguish CM-1 from SIH on brain MRI.
This is a retrospective case-control series comparing neuroimaging in consecutive adult subjects with CM-1 and SIH. Measurements obtained from brain MRI included previously reported measures of brain sagging: TE, slope of the third ventricular floor (3VF), pontomesencephalic angle (PMA), mamillopontine distance, lateral ventricular angle, internal cerebral vein–vein of Galen angle, and displacement of iter (DOI). Clivus length (CL), an indicator of posterior fossa size, was also measured. Measurements for the CM-1 group were compared to those for the entire SIH population (SIHall) as well as a subgroup of SIH patients with > 5 mm of TE (SIHTE subgroup).
Highly significant differences were observed between SIHall and CM-1 groups in the following measures: TE (mean ± standard deviation, 3.1 ± 5.7 vs 9.3 ± 3.5 mm), 3VF (−16.8° ± 11.2° vs −2.1° ± 4.6°), PMA (44.8° ± 13.1° vs 62.7° ± 9.8°), DOI (0.2 ± 4.1 vs 3.8 ± 1.6 mm), and CL (38.3 ± 4.5 vs 44.0 ± 3.3 mm; all p < 0.0001). Eight (16%) of 50 SIH subjects had TE > 5 mm; in this subgroup (SIHTE), a cutoff value of < −15° for 3VF and < 45° for PMA perfectly discriminated SIH from CM-1 (sensitivity and specificity = 1.0). DOI showed perfect specificity (1.0) in detecting SIH among both groups. No subjects with SIH had isolated TE without other concurrent findings of midbrain sagging.
Measures of midbrain sagging, including cutoff values for 3VF and PMA, discriminate CM-1 from SIH and may help to prevent misdiagnosis and unnecessary surgery.
Apostolos Mintelis, Tetsuro Sameshima, Ketan R. Bulsara, Linda Gray, Allan H. Friedman, and Takanori Fukushima
Maximizing intradural exposure via the extreme lateral infrajugular transcondylar–transtubercular exposure (ELITE) approach depends on understanding the fundamental anatomy of the jugular tubercle (JT). Drilling the JT can maximize the extent of exposure achieved with the ELITE approach. Removing the JT is critical for optimizing access to the inferior and midclival areas, vertebrobasilar artery junction, and ventral pons and medulla.
In this cadaveric study, the individual structural variations in the JT were evaluated in 100 split occipital bones. The mean length of the JT was 1.65 ± 0.36 cm (range 1.2–3 cm); its mean width was 1.15 ± 0.16 cm (range 0.7–1.7 cm); and its mean thickness was 0.61 ± 0.15 cm (range 0.2–1 cm). The authors analyzed the difference in morphometric data with regard to right and left sides and found no statistically significant difference between the two sides. Furthermore, data from the morphometric study were compared with the results of 20 measurements obtained from three-dimensional computed tomography (3D CT) scans. Accordingly, the mean length of the JT was 1.35 ± 0.15 cm (range 1–2.8 cm); the mean width, 1.10 ± 0.12 cm (range 0.8–1.3 cm); and the mean thickness, 0.51 ± 0.18 cm (range 0.2–1 cm).
Morphometric data on the JT contribute significantly to the neurosurgeon’s task of skull base drilling. The 3D CT scans were useful in the preoperative planning.
Peter M. Grossi, Michael J. Ellis, Thomas J. Cummings, Linda L. Gray, Takanori Fukushima, and John H. Sampson
✓Cholesterol granulomas (CGs) are benign lesions resulting from an inflammatory reaction to cholesterol and hemosiderin. These masses most often arise within the temporal bone or nasal sinuses; intracerebral CGs are extremely rare. In this report the authors present an unusual case of a CG arising within the lateral ventricle.
The patient presented with transient hemiparesis and numbness. Computed tomography and magnetic resonance imaging demonstrated a cystic partially enhancing midline mass within the right lateral ventricle, expanding the ventricle and displacing the septum pellucidum. The patient underwent an interhemispheric, transcallosal resection of the lesion. Microscopic examination revealed a granulomatous inflammatory lesion containing cholesterol clefts, macrophages, and hemosiderin. Embedded within the granulomatous response were foci of tiny cystlike structures lined by nonciliated flattened cuboidal epithelium, consistent with the diagnosis of CG.
To the authors' knowledge this is the first reported case of CG presenting as an intraventricular mass. The origin of this lesion is unclear, but it may relate to prior traumatic brain injury. The authors describe the presentation, imaging findings, histopathological characteristics, and surgical treatment of this rare lesion and related pathological entities.