Clinical and Magnetic Resonance Imaging Characteristics of Quadrigeminal Cysts in Dogs

Abstract

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.

Intracranial Intra-arachnoid Diverticula and Cyst-like Abnormalities of the Brain

“…10,11,14,[16][17][18][19][20] Subarachnoid diverticula have been reported within the fourth ventricle in five nonbrachycephalic large breed dogs, indicating that the brachycephalic predisposition may only occur for IADs in dogs. Age at presentation varies widely, and is likely related to whether the IAD is incidental or contributes to clinical signs along with another intracranial disease.…”

“…They might be an incidental imaging or postmortem finding 18,19,23,27-29 or give Platt et al rise to severe neurologic dysfunction. 5,11,15,16,[18][19][20][21]23,27,29,30 In more than half of dogs retrospectively evaluated for intracranial disease, an IAD was considered an incidental finding. 19 Clinical signs that were attributable to the cysts in this study included focal or generalized seizures and cerebellar/vestibulocerebellar signs; however paresis, a reduced level of consciousness, facial nerve paresis, and neck pain have also been reported.…”

“…5,10-21 An extensive review of canine MRI brain scans documented a low prevalence of the condition, with 0.7% of dogs being screened for brain disease affected. 19 Pathophysiology It has been postulated that during embryonic development the perimedullary mesh experiences a splitting in the arachnoid layer because of aberrant CSF flow; this mesh surrounds the developing neural tube and is normally divided by CSF flow into the pia and arachnoid layers. 18 Evaluation of the lining of these cysts has determined there to be multiple structural variants, which may explain their differential clinical behavior.…”

“…25,26 Three heterogeneous phenotypes of IAD (quadrigeminal) have been described in dogs: they can appear associated with either the third or fourth ventricle, or may have a loculated appearance and be associated with both third and fourth ventricles. 19 The heterogeneous appearance and lack of a true "cyst" wall has led some to refer to them as supracollicular fluid accumulations instead of IADs. 19 The association found between ventricles in some of these cysts must not be confused with the term communicating and noncommunicating IADs, because this refers to their communication with the subarachnoid space, 7,18,26 which cannot be determined with conventional imaging.…”

“…19 The heterogeneous appearance and lack of a true "cyst" wall has led some to refer to them as supracollicular fluid accumulations instead of IADs. 19 The association found between ventricles in some of these cysts must not be confused with the term communicating and noncommunicating IADs, because this refers to their communication with the subarachnoid space, 7,18,26 which cannot be determined with conventional imaging.…”