Clinical and Magnetic Resonance Imaging Characteristics of Quadrigeminal Cysts in Dogs

Abstract

Background: Quadrigeminal cysts (QC) are the most common intracranial intra-arachnoid cysts in dogs, primarily affecting small breeds. Clinical significance is controversial.Hypothesis: Male, brachycephalic, small breed dogs are predisposed to QC, and objective measurement of parenchymal compression can distinguish clinically relevant QC from incidental findings.Animals: A total of 4,100 client-owned dogs. Methods: A retrospective study that recorded signalment, history, clinical signs, and magnetic resonance imaging features. The degree of brain compression was evaluated in the presence of relevant clinical signs. The percentage compression of cerebellum and forebrain was calculated by comparing the expected to the actual diameter and longitudinal dimension, respectively.Results: QC were diagnosed in 28 dogs, of which 21 (75%) were small breed dogs. Fifteen dogs (54%) were brachycephalic. Eighteen dogs were male, and 10 were female. Cerebellar, occipital lobe, or compression in both areas occurred in 86% (24/28 dogs). Clinical signs included focal and generalized seizures in 5 dogs and cerebellar signs in 6 dogs. Mean occipital lobe compression was 17% (SD 5 4) in clinically affected and 10% (SD 5 3) in normal dogs (P 5 .006). Occipital lobe compression .14% was always associated with clinical signs. The mean cerebellar compression was 18%, but there was no association between compression and clinical signs. The animals were more likely to develop clinical signs if both areas were compressed (P 5 .04).Conclusions and Clinical Importance: Parenchymal compression by QC can be incidental, and other central nervous system diseases must be excluded when assessing the clinical significance of QC. However, occipital lobe compression over 14% is likely to cause clinical signs.

Quadrigeminal Arachnoid Cysts in a Kitten and a Dog

“…The cyst wall is devoid of blood vessels, and inflammatory changes or hemorrhage seldom occurs. 1,7,9,14 The histologic composition of the cysts in the kitten and dog of the current report is consistent with arachnoid cysts. The inflammatory changes and hemorrhage seen in the Yorkshire Terrier were most likely a consequence of the concurrent necrotizing encephalitis.…”

“…Given the location of the cysts, both would be categorized as QACs, an uncommonly reported lesion in veterinary medicine. Aside from one large case series of 28 dogs, 9 most reports of QACs in dogs have involved a few individuals. 6,8,[10][11][12]18,19 Most of the previous reports, including the series of 28 cases, have characterized the cysts based on computed tomography or magnetic resonance imaging in live patients, and detailed descriptions of morphologic changes associated with QAC are lacking in veterinary medicine.…”

“…7 Microscopically, their walls are formed from splitting of the arachnoid membrane, with an inner and outer leaflet surrounding the cyst cavity, and may be secondary to a congenital deficiency within the arachnoidal trabeculae. 4,7,9,14 The fluid within the cysts is thought to be normal CSF. 3,4,6,7,9,14 Given the kitten's age and lack of contributing lesions, its QAC was thought to be congenital.…”

“…4,7,9,14 The fluid within the cysts is thought to be normal CSF. 3,4,6,7,9,14 Given the kitten's age and lack of contributing lesions, its QAC was thought to be congenital. The only previously published feline case of intra-arachnoid cyst formation was an extracranial spinal cyst that was thought to be congenital.…”

Most commonly used sequences and clinical protocols for brain and spine magnetic resonance imaging allowing better identification of pathological changes in dogs

“…There are different reports that have distinguished the MR signs in dogs with hydrocephalus, cerebellar degeneration, necrotizing encephalitis, granulomatous meningoencephalitis, infarcts, age-related degeneration, spinal cord hernias, wobbler syndrome, arachnoid cysts, syringohydromyelia associated with Chiari-like malformation in the Cavalier King Charles spaniel (Fig. 1), discospondylitis, atlantoaxial instability, meningeal calcification, hydromyelia, mechanical damage, and brain and spinal tumors (Vullo et al 1997, Gonzalo-Orden et al 2000, Kimotsuki et al 2005, Besalti et al 2006, Garosi et al 2006, Okada et al 2006, Matiasek et al 2007, Couturier J et al 2008, Sturges et al 2008, Carrera et al 2009, Cerda-Gonzalez S et al 2009, Young et al 2009, Gavin PR 2011.…”