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.
Jong G. Park, Ranjith Babu, Peter G. Kranz, Roger E. McLendon, and Cory Adamson
Intracranial dermoid cysts are rare congenital lesions that typically occur in the cisternal spaces. However, exceptionally rare cases of intraaxial involvement have been reported, with only 8 cases having been described in the literature. The authors report the first case of an intraaxial dermoid cyst located in the medulla and the first occurrence in an elderly patient. They also review the literature of the existing intraparenchymal cases and provide treatment guidelines. A 66-year-old man presented with slowly progressive dysphagia, left lower-extremity numbness, nausea, and hyperhidrosis. Neurological examination revealed decreased pinprick sensation of the left side of his face and body, and decreased vibratory sensation in his left lower extremity. Additionally, he had an unusual extraocular movement in which abduction of the eye resulted in closure of the contralateral eye. Magnetic resonance imaging revealed a nonenhancing cystic lesion centered in the medulla. The patient underwent a suboccipital craniotomy with laminectomy of C1–2 for excision of the cyst, with subtotal resection due to adherence of the cyst wall to the brainstem. At follow-up 7.5 years after surgery, the patient's neurological examination was stable. Magnetic resonance imaging did not reveal any progression or recurrence of the cyst. As the cyst wall is typically adherent to surrounding structures, resection is usually subtotal due to the risk of neurological deficits. As there have been no cases of progression after subtotal resection, gross-total resection is not warranted for the treatment of these lesions.
Charles W. Kanaly, Ankit I. Mehta, Dale Ding, Jenny K. Hoang, Peter G. Kranz, James E. Herndon II, April Coan, Ian Crocker, Anthony F. Waller, Allan H. Friedman, David A. Reardon, and John H. Sampson
Robust methodology that allows objective, automated, and observer-independent measurements of brain tumor volume, especially after resection, is lacking. Thus, determination of tumor response and progression in neurooncology is unreliable. The objective of this study was to determine if a semi-automated volumetric method for quantifying enhancing tissue would perform with high reproducibility and low interobserver variability.
Fifty-seven MR images from 13 patients with glioblastoma were assessed using our method, by 2 neuroradiologists, 1 neurosurgeon, 1 neurosurgical resident, 1 nurse practitioner, and 1 medical student. The 2 neuroradiologists also performed traditional 1-dimensional (1D) and 2-dimensional (2D) measurements. Intraclass correlation coefficients (ICCs) assessed interobserver variability between measurements. Radiological response was determined using Response Evaluation Criteria In Solid Tumors (RECIST) guidelines and Macdonald criteria. Kappa statistics described interobserver variability of volumetric radiological response determinations.
There was strong agreement for 1D (RECIST) and 2D (Macdonald) measurements between neuroradiologists (ICC = 0.42 and 0.61, respectively), but the agreement using the authors' novel automated approach was significantly stronger (ICC = 0.97). The volumetric method had the strongest agreement with regard to radiological response (κ = 0.96) when compared with 2D (κ = 0.54) or 1D (κ = 0.46) methods. Despite diverse levels of experience of the users of the volumetric method, measurements using the volumetric program remained remarkably consistent in all users (0.94).
Interobserver variability using this new semi-automated method is less than the variability with traditional methods of tumor measurement. This new method is objective, quick, and highly reproducible among operators with varying levels of expertise. This approach should be further evaluated as a potential standard for response assessment based on contrast enhancement in brain tumors.