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Brain Bioelectric Activity

Hypertrophic Pachymeningitis in a Dog

A 3-year-old Whippet presented with progressive masticatory muscle atrophy, lethargy, and vestibular signs.

MR study showed severe thickening and strong contrast enhancement of the pachymeninges (ie. limited to the dura with no extension into the cerebral sulci). There was a subtle non-enhancing layer within the thickened meninges. Marked contrast enhancement was also present around the trigeminal nerves with marked atrophy of the masticatory muscles. Hypertrophic pachymeningitis was suspected with secondary multiple cranial neuropathy. The dog responded very well to immuno-suppressive treatment.

On T1-weighted post-contrast images, the main layer of dural enhancement is contrasted by an underlying area of low signal. Many cases show lesions characterized by two layers of contrast enhancement surrounding a center iso- to hypointense to the grey matter on T1-weighted images after gadolinium injection. Two hypotheses are proposed: a dilation of the subarachnoid space with fluid and separation between the dural and pial layer or inflamed lesion edges surrounding a fibrotic center. The meningeal enhancement and thickening are characteristic of dural enhancement, limited to the pachymeninges without extension into the sulci. The most common site for meningeal enhancement is the dorso-lateral part of each cerebral hemisphere in either the parietal or frontal cortex. The falx cerebri and the tentorium cerebellum are often involved.

For further information on hypertrophic pachymeningitis click on the link below.

Courtesy Koen Santifort from Evidensia Arnhem.

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