MRI Findings of Early-Stage Hyperacute Hemorrhage Causing Extramedullary Compression of the Cervical Spinal Cord in a Dog with Suspected Steroid-Responsive Meningitis-Arteritis

Steroid-responsive meningitis-arteritis: What have we learned since 2010? A narrative review

Steroid-responsive meningitis-arteritis (SRMA) occurs as an immune-mediated, inflammatory, and non-infectious disorder of juvenile and young-adult dogs. In principle, SRMA is divided into two clinical courses: during the typical acute form, dogs are presented with fever, cervical hyperaesthesia, and reluctance to move. The more protracted form most probably emerges after insufficient immunosuppressive treatment or relapses, with additional neurologic deficits localized in the cervical and thoracolumbar spinal cord or multifocally. The trigger leading to SRMA still remains an unsolved riddle for immunologists and clinical neurologists. In the past, many attempts have been made to clarify the etiology of this disease without success. The purpose of writing this narrative review about SRMA is to summarize new insights on the pathogenesis of SRMA with a focus on immunologic dysregulation. Furthermore, unusual manifestations of the disease, new diagnostic approaches using possible laboratory biomarkers or diagnostic imaging tools, and potential innovative treatment strategies are discussed.

Case report: Intracranial and spinal subarachnoid hemorrhage in a dog with Angiostrongylosis

A 1-year-old male intact Staffordshire terrier, born and raised in the Netherlands, was presented with a 3-week history of progressive lethargy and spinal, predominantly cervical, hyperesthesia. Other than hyperthermia and cervical hyperesthesia, general and neurological examination did not reveal any abnormalities. Comprehensive hematological and biochemical tests were considered normal. Magnetic resonance imaging of the craniocervical region revealed heterogeneity of the subarachnoid space, characterized by pre-contrast T1W hyperintensity, corresponding to a T2* signal void. Extending from the caudal cranial fossa to the level of the third thoracic vertebra, there were uneven patchy extra-parenchymal lesions that caused mild spinal cord compression, most marked at the level of C2. At this level, the spinal cord showed an ill-defined hyperintense T2W intramedullary lesion. Mild intracranial and spinal meningeal contrast enhancement was evident on post-contrast T1W images. Subarachnoid hemorrhage was suspected, and further diagnostic tests including Baermann coprology resulted in a diagnosis of hemorrhagic diathesis caused by an Angiostrongylus vasorum infection. The dog rapidly responded to treatment with corticosteroids, analgesic medication, and antiparasitic treatment. Follow-up over 6 months yielded complete clinical remission and repeatedly negative Baermann tests. This case report details clinical and magnetic resonance imaging findings in a dog with subarachnoid hemorrhage associated with an Angiostrongylus vasorum infection.

Non-traumatic hemorrhagic myelopathy in dogs

BACKGROUND

Non-traumatic spinal cord hemorrhage (NTSH) is an uncommon cause of myelopathy in dogs.

OBJECTIVES

Describe the clinical characteristics, concurrent medical conditions and underlying causes, magnetic resonance imaging (MRI) findings and outcome in dogs with NTSH.

ANIMALS

Dogs diagnosed with NTSH using gradient echo T2-weighted (GRE) sequences with or without histopathological confirmation of hemorrhage were included. Dogs with a traumatic cause were excluded, including those with compressive intervertebral disc extrusion.

METHODS

Retrospective descriptive study; the databases of 2 referral hospitals were searched between 2013 and 2021.

RESULTS

Twenty-three dogs met inclusion criteria. The onset of signs was acute and progressive in 70% of cases; spinal hyperesthesia was variable (48%). Hemorrhage was identified in the thoracolumbar spinal segments in 65% of dogs. An underlying cause was identified in 65% of cases. Angiostrongylus vasorum represented 18% of the total cohort, followed by steroid-responsive meningitis arteritis (SRMA; 13%). Overall, 64% of dogs had a good or excellent outcome, regardless of cause; which was increased to 100% for SRMA, 75% for A. vasorum and 75% for idiopathic NTSH. Outcome was not associated with neurological severity. Recovery rate was 67% and 50% for nociception-intact and nociception-negative dogs, respectively.

CONCLUSIONS

Larger prospective studies would be required to define prognostic factors for dogs with NTSH, but outcome appeared to be most influenced by the underlying cause, as opposed to neurological severity at presentation.

Hemophilia A Resulting in Severe Hyperesthesia Due to Extraparenchymal Spinal Cord Hemorrhage in a Young Golden Retriever Puppy

A ten-week-old male Golden retriever puppy was presented with severe hyperesthesia, mild neurological deficits and episcleral bleeding. Clotting times showed a normal prothrombin time (PT) and prolonged activated partial thromboplastin time (aPPT). Computed tomography (CT) of the vertebral column showed intradural, extraparenchymal hyperattenuating changes on precontrast CT images and epidural mass lesions, suggestive of hematorrhachis. Hemophilia A was confirmed by a low-factor VIII activity (FVIII:C). Although the dog improved clinically with intravenous analgesia and cage rest, it was euthanized by the owners’ choice because of the risk of developing future episodes of spontaneous hemorrhage. In young male puppies with severe hyperesthesia and mild neurological deficits, hemophilia A should be considered as a possible differential diagnosis.

Clinical, Diagnostic, and Imaging Findings in Three Juvenile Dogs With Paraspinal Hyperesthesia or Myelopathy as a Consequence of Hemophilia A: A Case Report

Three juvenile dogs presented with an acute onset of paraspinal hyperesthesia and/or neurologic deficits. These dogs underwent anesthesia for MRI and additional diagnostics. The thoracolumbar MRI in Dog 1 revealed an accumulation of T2-weighted (T2W) hyperintense, T1-weighted (T1W) iso- to hyperintense, contrast enhancing extradural material. The differential diagnoses were meningitis with secondary hemorrhage or empyema or late subacute hemorrhage. The initial cervical MRI in Dog 2 revealed T1W meningeal contrast enhancement suspected to be secondary to meningitis. A repeat MRI following neurologic decline after CSF sampling revealed a large area of T2W and T1W hyperintensity between fascial planes of the cervical musculature as well as T2W iso- to hyperintense and T1W iso- to hypointense extradural material at the level of C1 consistent with hemorrhage. The cervical MRI in Dog 3 revealed T2W hyperintense and T1W iso- to hypointense extradural compressive material consistent with hemorrhage. Dogs 1 and 2 underwent CSF sampling and developed complications, including subcutaneous hematoma and vertebral canal hemorrhage. Dog 3 underwent surgical decompression, which revealed a compressive extradural hematoma. In each case, a hemophilia panel including factor VIII concentration confirmed the diagnosis of hemophilia A. Dog 1 had a resolution of clinical signs for ~5 months before being euthanized from gastrointestinal hemorrhage. Dog 2 was euthanized due to neurologic decompensation following CSF sampling. Dog 3 did well for 2 weeks after surgery but was then lost to follow-up. This case series provides information on clinical signs, MRI findings, and outcome in 3 juvenile dogs with hemophilia A that developed neurologic deficits or paraspinal hyperesthesia secondary to spontaneous or iatrogenic vertebral canal hemorrhage. Hemophilia A should be considered as a differential in any young dog presenting with an acute onset of hyperesthesia with or without neurologic deficits. This diagnosis should be prioritized in young male dogs that have other evidence of hemorrhage on physical exam.