Association among raised intraventricular pressure, clinical signs, and magnetic resonance imaging findings in dogs with congenital internal hydrocephalus.

Background: Dogs with internal hydrocephalus do not necessarily have high intraventricular pressure (IVP).

Hypothesis/objectives: Not all reported MRI findings indicate high IVP and some clinical signs might be associated with elevated IVP and syringomyelia.

Animals: Fifty-three dogs.

Materials and methods: Cross-sectional study. Clinical signs and MRI findings were evaluated for an association of IVP >12 mm Hg and syringomyelia.

Results: High IVP was associated with obtundation OR 4.64 (95% CI 1.27-16.93) (P = .02), head tilt OR 6.42 (95% CI 1.08-37.97) (P = .04) and nystagmus OR 8.24 (95% CI 1.44-47.07) (P = .02). Pain was associated with syringomyelia OR 3.4 (95% CI 0.98-11.78) (P = .05). The number of affected ventricles was associated with high IVP OR 2.85 (95% CI 0.97-8.33) (P = .05) and syringomyelia OR 12.74 (95% CI 2.93-55.4) (P = .0007). Periventricular edema OR 24.46 (95% CI 4.54-131.77), OR 7.61 (95% CI 1.91-30.32) (P < .0002, P = .004) and signal void sign OR 17.34 (95% CI 4.01-74.95), OR 4.18 (95% CI 1.16-15.02) (P < .0001, P = .03) were associated with high IVP and syringomyelia. The probability for syringomyelia is lower with disruption of the internal capsule OR 0.19 (95% CI 0.05-0.72) (P = .01) and higher VBR OR 0.25 (95% CI 0.1-0.63) (P = .004).

Conclusions and clinical importance: Previously reported MRI findings are not predictive of high IVP. Clinical signs and MRI findings should be used to make a diagnosis of internal hydrocephalus in dogs with or without high IVP.