Imaging and histopathologic features of reversible nerve root and peripheral nerve edema secondary to disc herniation in a cat

Abstract

Nerve root enlargement with increased contrast uptake has been reported in dogs and humans secondary to nerve root compression. In cats, nerve root enlargement and contrast uptake only have been reported in association with inflammatory and neoplastic diseases, but not as a sequela to nerve root compression. An 8-year-old oriental short hair cat was presented with acute neurologic deficits consistent with left-sided sciatic nerve deficit and possible L6-S1 myelopathy. Magnetic resonance imaging (MRI) was performed and identified compression of the cauda equina and L7 nerve root associated with intervertebral disc herniation (IVDH) at L6-L7 as well as widespread sciatic nerve enlargement with moderate rim enhancement. A hemilaminectomy was performed to evacuate herniated disc material. The nerve root was biopsied and submitted for histological evaluation. Interstitial nerve edema was diagnosed. Follow-up MRI 3 months postoperatively showed complete remission of the changes. Nerve root thickening together with contrast enhancement may represent nerve edema in cats secondary to IVDH.

Prevalence, clinical presentation and MRI of intervertebral disc herniations in cats

“…The mean age of the cats in our study was 8.7 years, which is in agreement with the mean age of all the published feline IVDH cases thus far (8.3 years). 7–38 This occurrence in mature cats has been reported previously, 30,35 and is consistent with several post-mortem studies on feline intervertebral disc degeneration and herniation that found an increased occurrence of this condition in older animals. 1–4 When considering each type of IVDH separately, previously reported cats affected by IVDP and IVDE had a similar mean age (8.6 years), 7–14,16,18–23,25–27,29–36,38 wher...…”

“…Only 185 cats clinically affected by IVDH have been reported in the past 50 years, most of them described from 2011 to date. 24–29,33–38 Moreover, several studies have separately investigated various features of each different type of IVDH, mainly as individual case reports or case series including low numbers of cats. Thus, a comprehensive overview regarding the overall clinical and MRI characteristics of this disease is lacking.…”

“…In cats, a sex predisposition to IVDH has not been reported, although males seem to be over-represen-ted. 7,10,12–19,21,23,25–27,29–38 Among published feline IVDE cases, a male predisposition could be suspected owing to a male-to-female ratio of 1.8. 29,34,35,38 In our study, a strong association between sex and type of IVDH was found, with males being significantly more prone to being affected by IVDE and females by ANNPE.…”

“…The first report of symptomatic feline IVDH dates back to 1971. 7 Since then, several clinical cases have been published, the vast majority as case reports 8–29 or case series numbering 10 or fewer cats, 30–34 mirroring the low prevalence of this condition in the feline population. In the past 5 years, only three larger retrospective studies have been published, two describing IVDHs limited to the thoracolumbar region of the spine in a population of 31 35 and 35 cats, 35,36 and the other focusing on a single type of IVDH (namely, acute non-compressive nucleus pulposus extrusion [ANNPE]).…”

Lumbar intervertebral foraminal disc extrusion in a cat

“…Herzig et al 7 presented a case report of reversible nerve root and peripheral nerve root oedema secondary to IVDE. While this case had a foraminal component, the neurological examination was indicative of an L6–S1 localisation which, along with the severe MRI changes, is different to our presentation as this cat had obvious neurological deficits present on examination.…”