Abstract
BACKGROUND AND PURPOSE: The “ears of the lynx” MR imaging sign has been described in case reports of hereditary spastic paraplegia with a thin corpus callosum, mostly associated with mutations in the spatacsin vesicle trafficking associated gene, causing Spastic Paraplegia type 11 (SPG11). This sign corresponds to long T1 and T2 values in the forceps minor of the corpus callosum, which appears hyperintense on FLAIR and hypointense on T1-weighted images. Our purpose was to determine the sensitivity and specificity of the ears of the lynx MR imaging sign for genetic cases compared with common potential mimics.
MATERIALS AND METHODS: Four independent raters, blinded to the diagnosis, determined whether the ears of the lynx sign was present in each of a set of 204 single anonymized FLAIR and T1-weighted MR images from 34 patients with causal mutations associated with SPG11 or Spastic Paraplegia type 15 (SPG15). 34 healthy controls, and 34 patients with multiple sclerosis.
RESULTS: The interrater reliability for FLAIR images was substantial (Cohen κ, 0.66–0.77). For these images, the sensitivity of the ears of the lynx sign across raters ranged from 78.8 to 97.0 and the specificity ranged from 90.9 to 100. The accuracy of the sign, measured by area under the receiver operating characteristic curve, ranged from very good (87.1) to excellent (93.9).
CONCLUSIONS: The ears of the lynx sign on FLAIR MR imaging is highly specific for the most common genetic subtypes of hereditary spastic paraplegia with a thin corpus callosum. When this sign is present, there is a high likelihood of a genetic mutation, particularly associated with SPG11 or SPG15, even in the absence of a family history.
ABBREVIATIONS:
- AUC
- area under the curve
- HSP-TCC
- hereditary spastic paraplegia with a thin corpus callosum
- ROC
- receiver operating characteristic curve
Footnotes
Disclosures: Marcondes C. França Jr—UNRELATED: Fundação de Amparo à Pesquisa do Estado de São Paulo grant 2013/01766–7, Comments: The Fundação de Amparo à Pesquisa do Estado de São Paulo is a government agency in Brazil that funded genetic testing and MRI acquisitions.* Bart P. van de Warrenburg—UNRELATED: Grants/Grants Pending: Hersenstichting, ZonMw, Bioblast Pharma*; Royalties: Reed Elsevier*; Travel/Accommodations/Meeting Expenses Unrelated to Activities Listed: International Parkinson and Movement Disorders Society. Berry Kremer—UNRELATED: Board Membership: European Huntington's Disease Network/Child Health and Development Institute, Comments: travel cost reimbursements; Expert Testimony: Veduma Medical Expertise, Zaltbommel, the Netherlands; Comments: various book chapters; Stock/Stock Options: Fresenius, Germany. Joost Nicolai—UNRELATED: Payment for Lectures Including Service on Speakers Bureaus: SEPION, the Netherlands, Comments: Money was paid for organizing an epilepsy course twice a year for residents; Comments: Fee for several chapters in neurology books (Dutch). Joseph C. Masdeu—UNRELATED: Board Membership: GE Healthcare; Expert testimony: National Collegiate Athletic Association; Grants/Grants Pending: Avanir Pharmaceuticals, Acadia, Biogen, Eli Lilly, AbbVie, Novartis, National Institutes of Health, Comments: clinical trials*; Payment for Lectures Including Service on Speakers Bureaus: Eli Lilly, Comments: amyloid imaging; Royalties: Walters Kluwer, Comments: localization in Neurology; Travel/Accommodations/Meeting Expenses Unrelated to Activities Listed: International Collaboration with Siemens.* Michael D. Gregory—UNRELATED: Employment: National Institutes of Mental Health, Inova Medical Group. *Money paid to the institution.
This study was partially funded by the Chao, Graham, Harrison, and Nantz Funds of the Houston Methodist Foundation. Portions of the data studied were obtained under protocol OHSRP 12231 and were supported (in part) by the National Institutes of Mental Health Intramural Research Program.
This work does not necessarily reflect the views of the US government or the National Institutes of Health.
- © 2019 by American Journal of Neuroradiology