Neurological signs and results of magnetic resonance imaging in 40 cavalier King Charles spaniels with Chiari type 1‐like malformations

Abstract

In human beings a Chiari type 1 malformation is a developmental condition characterised by cerebellar herniation and syringohydromyelia. Abnormalities compatible with such a malformation were identified by magnetic resonance imaging in 39 cavalier King Charles spaniels with neurological signs and in one neurologically normal cavalier King Charles spaniel that was examined postmortem. The dogs with these abnormalities had a wide variety of neurological signs, but there was no apparent correlation between the neurological signs and the severity of cerebellar herniation, syringohydromyelia or hydrocephalus.

Cerebellar and hindbrain motion in Chiari malformation with and without syringomyelia

“…Interestingly, the average tonsillar motion (CLM/CM-I with syrinx values given) was much greater and more variable in dogs (4.18 ± 2.63 mm according to Driver et al 16 ) than that in humans (current study 0.81 ± 0.47 mm; Bunck et al 5 1.0 ± 0.6 mm; Cousins and Haughton 11 0.61 ± 0.03 mm) despite similar or smaller degrees of herniation. 12,14,31 Whether increased cerebellar motion has a different effect on the canine system is unknown. Morphometric studies further suggest a probable difference between human and canine conditions.…”

Evaluation of Cerebrospinal Fluid in Cavalier King Charles Spaniel Dogs Diagnosed with Chiari-Like Malformation with or without Concurrent Syringomyelia

“…Chiari-like malformation was defined as an impingement of the cerebellum and subsequent indentation by the occipital bone or as cerebellar herniation through the foramen magnum. 18 Syringomyelia was defined as hyperintense lesions on the transverse and/or sagittal T2-weighted images with maximal dorsoventral dimension greater than 2 ml. 11,20 All images were subsequently reviewed using image viewer software, b and syrinx size was measured by a boardcertified neurologist.…”

“…3 The disease is recognized on magnetic resonance (MR) imaging as relatively reduced caudal fossa volume, with subsequent foramen magnum herniation of the cerebellum, 11,18,23 and has been associated with the development of fluid-filled cavities within the spinal cord parenchyma (syringomyelia [SM]). 11,17,21 CM/SM is a debilitating and painful disease complex likely to be multifactorial in origin, secondary to altered cerebrospinal fluid (CSF) dynamics and damage to the spinal cord parenchyma; clinical signs frequently exhibited by affected dogs include phantom scratching and vocalization, cervical scoliosis, thoracic and pelvic limb ataxia, and thoracic limb paresis.…”

Assessment of cerebellar pulsation in dogs with and without Chiari-like malformation and syringomyelia using cardiac-gated cine magnetic resonance imaging

“…For each of the 20 bFFE images generated during the cardiac cycle, linear measurements were made using a similar technique to that described previously (Lu et al, 2003;Cerda-Gonzalez et al, 2009a;Upchurch et al, 2011). Measurements included the height of the foramen magnum (measured from the ventral most aspect of the supraoccipital bone to the caudal basisphenoid bone) and the length of cerebellar herniation (measured perpendicular from the line of the foramen magnum to the tip of the cerebellar vermis) (Fig.…”

“…CM was defined as evidence of caudal cerebellar herniation into the foramen magnum or indentation by the supraoccipital bone (Lu et al, 2003). A syrinx was defined as a fluid-containing cavity within the spinal cord parenchyma with a diameter P2 mm .…”