Subdural hematoma of the brainstem in a dog: magnetic resonance findings and treatment

An 8-year-old, spayed female Dalmatian with a history of seizures was evaluated for cervical pain and bilateral scleral hemorrhages. Diagnostic evaluations revealed a mass displacing the ventral brainstem on magnetic resonance imaging (MRI). The mass was surgically removed and histologically confirmed to be a hematoma. The dog's neurological signs resolved completely after surgery. Although extradural, subdural, subarachnoid, and intraparenchymal hemorrhages have been reported in dogs and cats, this is the first known report of a subdural hematoma of the ventral brainstem in a dog. On the basis of the history and the appearance of the subdural hematoma on MRI, a traumatic event during the seizure episodes was considered the most likely cause of the subdural hematoma in this case.     

Canine calvarial subperiosteal hematomas are fluid to soft tissue attenuating mass‐like lesions with smoothly marginated peripheral mineralization on CT

Subperiosteal hematomas are accumulations of blood between a bone and the periosteum leading to elevation of the periosteum. When ossified they have a mineralized outer rim. For this retrospective, multi‐institutional case series, medical records were searched to identify dogs that underwent CT for focal calvarial swellings noted acutely after trauma. A total of four dogs were included. Computed tomography images were reviewed for each case. The focal swellings had progressed in size during the weeks after the head trauma until the time of imaging. Findings in all cases included a fluid to soft tissue attenuating mass‐like lesion with smoothly marginated peripheral mineralization. Diagnosis was confirmed in two cases by cytology and/or histopathology. Therefore, authors recommend that subperiosteal hematoma be included in the differential diagnosis list for dogs with these clinical and CT characteristics. Based on our review of the literature, this is the first report to describe the CT features of calvarial subperiosteal hematomas in dogs.     

IMAGING DIAGNOSIS—NEURONAL CEROID LIPOFUSCINOSIS WITH A CHRONIC SUBDURAL HEMATOMA

A subdural hematoma was found to accompany neuronal ceroid lipofuscinosis in an 11‐month‐old Dachshund. Results from clinical, magnetic resonance (MR) imaging, histopathologic, ultrastructural, and molecular assessments are described. The dog had a 3‐month history of progressive neurologic signs. In MR images, there was severe asymmetric cerebral atrophy with a subdural hematoma. Histopathologically, there was autofluorescent, periodic acid–Schiff‐positive lipopigment in neurons and transmission electron microscopy confirmed a typical curvilinear profile of the storage bodies. We hypothesize that rapid brain atrophy contributed to the subdural hematoma formation, a complication not described previously in dogs with neuronal lipofuscinosis.     

INTRACRANIAL INTRA-ARACHNOID CYST WITH INTRACYSTIC HEMORRHAGE IN TWO DOGS

Clinical signs, magnetic resonance imaging (MRI) features, treatment, and outcome of two adult dogs with neurologic dysfunction resulting from hemorrhage into a quadrigeminal intracranial intra-arachnoid cyst are described. In dog 1, the cyst was hyperintense to cerebrospinal fluid (CSF) on T1-weighted MRI and hypointense to CSF on T2-weighted images. In dog 2, the cyst was isointense to CSF on T1- and T2-weighted images. Both dogs were treated with craniotomy and cyst fenestration. A large blood clot was removed from the lumen of the cyst in each dog. Dog 1 is clinically normal 3.5 years post-surgery and has a persistent cyst. Dog 2 had a good initial response to therapy but was euthanized 2.5 years post-operatively due to generalized seizures. The late onset of clinical signs in these dogs most likely resulted from hemorrhage into the cyst. Surgical fenestration and hematoma removal appear to provide a satisfactory treatment for adult dogs with an intracranial intra-arachnoid cyst and intracystic hemorrhage. Persistence of the cyst may occur in some dogs.     

Signs consistent with syringobulbia may be detected in dogs undergoing MRI

Syringobulbia is a pathologic condition characterized by one or more fluid‐filled cavities within the brainstem. This retrospective case series describes observations in eight dogs with syringobulbia diagnosed during MRI. All dogs were adult, small‐breed dogs with concurrent syringomyelia and neurologic deficits localized to sites rostral to the spinal cord, which cannot be explained by syringomyelia (eg, six dogs had vestibular signs). On MRI, the fluid‐filled cavities had signal intensity characteristics like cerebrospinal fluid, were in the medulla oblongata, and were solitary in each dog. Initially, the shape of the cavity was a slit in five dogs and bulbous in two dogs. Magnetic resonance imaging was repeated in five dogs (6‐55 months of age). One dog had progression of syringobulbia from slit‐like to bulbous, and four dogs had unchanged slit‐like syringobulbia. One dog developed slit‐like syringobulbia after cranioplasty. A variety of medical and surgical treatments were performed with improvement of some but not all clinical signs. One dog died following surgery due to cardiopulmonary failure and the other seven dogs were alive at least 1 year after the initial diagnosis, which was the least time of follow‐up. One surviving dog developed a unilateral hypoglossal nerve deficit 2 months after the initial diagnosis and megaesophagus 14 months later. In conclusion, detecting a fluid‐filled cavity in the medulla oblongata consistent with syringobulbia is possible in dogs undergoing MRI. The cavity is likely acquired, slit‐like or bulbous, progressive, or static, and might be associated with breed size and neurologic signs localized to the medulla oblongata.     

Pituitary Macrotumor Causing Narcolepsy‐Cataplexy in a Dachshund

Familial narcolepsy secondary to breed‐specific mutations in the hypocretin receptor 2 gene and sporadic narcolepsy associated with hypocretin ligand deficiencies occur in dogs. In this report, a pituitary mass is described as a unique cause of narcolepsy‐cataplexy in a dog. A 6‐year‐old male neutered Dachshund had presented for acute onset of feeding‐induced cataplexy and was found to have a pituitary macrotumor on magnetic resonance imaging (MRI). Cerebral spinal fluid hypocretin‐1 levels were normal, indicating that tumor effect on the ventral lateral nucleus of the hypothalamus was not the cause of the dog's narcolepsy‐cataplexy. The dog was also negative for the hypocretin receptor 2 gene mutation associated with narcolepsy in Dachshunds, ruling out familial narcolepsy. The Dachshund underwent stereotactic radiotherapy (SRT), which resulted in reduction in the mass and coincident resolution of the cataplectic attacks. Nine months after SRT, the dog developed clinical hyperadrenocorticism, which was successfully managed with trilostane. These findings suggest that disruptions in downstream signaling of hypocretin secondary to an intracranial mass effect might result in narcolepsy‐cataplexy in dogs and that brain MRI should be strongly considered in sporadic cases of narcolepsy‐cataplexy.     

Green discolouration of urine following propofol infusion in a dog

A three‐year‐old, female neutered Weimaraner was presented with a history of neck pain and tetraparesis. MRI revealed an extradural mass at the level of C3 vertebra, which was thought to be a spinal abscess, and the dog was scheduled for surgical exploration the following morning. Overnight the dog developed an exaggerated ventilatory pattern, with paradoxical inward movement of the thorax on inspiration. Arterial blood gas analysis revealed respiratory acidosis and ventilator support was initiated to prevent excessive respiratory fatigue. During mechanical ventilation, anaesthesia was maintained using a propofol target‐controlled infusion system and, subsequently, the dog produced bright green urine in the urine collection system. Although previously documented in humans, this appears to be the first report of green urine in a dog following propofol use.     

Malignant pheochromocytoma presenting as a bradyarrhythmia in a dog

Objective: To describe a case of atrioventricular block and syncope secondary to systemic hypertension in a dog with malignant pheochromocytoma. Case Summary: A 13‐year‐old spayed female mixed‐breed dog presented following an acute onset of collapse. The dog was hypertensive and had paradoxical high‐grade second‐degree atrioventricular block with concurrent syncope. Initial emergent therapy included a nitroprusside infusion for the systemic hypertension and vagolytic therapy for the bradyarrhythmia. A left adrenal mass was seen on abdominal ultrasound and was further characterized by MRI. Following medical stabilization with phenoxybenzamine and propantheline, a left adrenalectomy was performed. Histological diagnosis was consistent with a malignant pheochromocytoma. Following tumor removal there has been no further hypertension, atrioventricular block or syncope. Unique information provided: This is the first documented case of a malignant pheochromocytoma presenting as syncope secondary to hypertension induced atrioventricular block.     

Hypophysitis,Panhypopituitarism, and Hypothalamitis in a Scottish Terrier Dog

A 6‐year old male neutered Scottish Terrier was referred with a 1 week history of progressive lethargy and anorexia. Neurological examination localized a lesion to the forebrain and hormonal testing showed panhypopituitarism. Magnetic resonance imaging (MRI) of the brain revealed a rounded, well‐defined, suprasellar central mass. The mass was slightly hyperintense to the cortical grey matter on T2‐weighted (T2W), hypointense on T1‐weighted (T1W) images and without T2* signal void. There was a central fusiform enhancement of the mass after contrast administration which raised the suspicion of a pituitary neoplasm. Rapid deterioration of the dog prevented further clinical investigations. Histopathologic examination revealed a lymphocytic panhypophysitis of unknown origin suspected autoimmune involving the hypothalamus (hypothalamitis). This is a unique case report of a dog presenting with inflammatory hypophysitis and hypothalamitis of suspected autoimmune origin with detailed clinical, MRI, histology and immunohistochemistry findings.     

IMAGING DIAGNOSIS—SPONTANEOUS INTRAMURAL CANINE DUODENAL HEMATOMA

A 9‐year‐old neutered female Pug with a 2‐week history of pancreatitis was presented for dyspnea, icterus, and intractable vomiting. Sonographically, the gallbladder, intrahepatic bile ducts, and common bile duct were distended. The pancreas was hypoechoic with hyperechoic peripancreatic fat. A mildly heterogeneous intramural mass was present in the muscularis layer of the descending duodenum. A presumptive diagnosis of pancreatitis and smooth muscle tumor of the duodenum leading to common bile duct obstruction was made. The dog died despite supportive care. Necropsy examination confirmed the presence of pancreatitis and an intramural duodenal hematoma.     

Craniotomy with cystoperitoneal shunting for treatment of intracranial arachnoid cysts in dogs

Objective— To describe a technique of decompressive craniotomy with cystoperitoneal shunt (CPS) placement for treatment of canine intracranial arachnoid cyst (IAC), and to evaluate outcome in 4 dogs. Study Design— Retrospective study. Animals— Dogs (n=4) with IAC. Methods— Medical records of dogs diagnosed with IAC by magnetic resonance imaging (MRI; 3 dogs) or computed tomography (CT; 1 dog) were evaluated. All dogs had varying degrees of neurologic dysfunction before surgery. A combined lateral (rostrotentorial)/suboccipital craniotomy was performed sacrificing the transverse sinus on the operated side. The rostral (ventricular) end of a low‐pressure valve shunt (3.0 mm outer diameter, 7.0 cm length) was placed transversely into the cyst cavity; the distal end was placed in the peritoneal cavity. All dogs were rechecked at various intervals by ≥1 of the authors either directly, by telephone consultation with owners, or both. Three dogs were imaged postoperatively (CT–1 dog; MRI–1; ultrasonography–1). Results— Intraoperative complications were limited to excessive transverse sinus hemorrhage requiring blood transfusion in 1 dog. There were no postoperative complications. Clinical signs of neurologic dysfunction resolved in 3 dogs and improved substantially in 1 dog. The latter dog required long‐term, low‐dose corticosteroid therapy. No dogs required repeat surgery. Mean follow‐up time was 23.8 months (range, 12–43 months). Collapse of the intracranial cyst was verified in 3 dogs with repeat imaging. In 2 dogs, there was no evidence of the cyst on CT or MRI; in the third dog, a small amount of fluid was demonstrated rostral to the cerebellum on ultrasonography, but there was no identifiable cyst. In 1 dog, the rostral aspect of the shunt had shifted; however, this was not associated with any clinical deterioration. Conclusion— Craniotomy with CPS placement was well tolerated and resulted in sustained improvement or resolution of dysfunction. Cyst decompression was verified in 3 dogs that were re‐imaged. None of the patients required re‐operation. Excessive transverse sinus hemorrhage is a potential danger that may necessitate blood transfusion. Other IAC patients treated with this method will need to be evaluated to fully evaluate its effectiveness. Clinical Significance— Craniotomy with CPS placement may be an effective treatment method for dogs clinically affected with IAC.     

Intracranial extension of retrobulbar blastomycosis (Blastomyces dermatitidis) in a dog

Blastomycosis (Blastomyces dermatitidis) is a fungal disease that is endemic in the southern United States. This case report illustrates the clinical, MRI and histopathologic findings in a dog with invasion of a retrobulbar blastomycotic lesion into the calvarium. A 5‐year‐old intact female Weimaraner was referred for a 2‐month history of change in behavior and recent onset of visual deficits. Magnetic resonance imaging (MRI) examination revealed a large (5.8 × 2.0 × 2.5 cm) mass extending from the left orbit through a circular defect in the left cranioventral aspect of the calvarium caudally to the level of the pituitary fossa and interthalamic adhesion. The mass was heterogeneously iso‐ to hypointense on T2‐W images, slightly hypointense on T1‐W images, did not attenuate on fluid attenuated inversion recovery (FLAIR) images, and did not show evidence of susceptibility artifact on T2*‐W gradient recalled echo (GRE) images. Vasogenic edema and associated mass effect were noted. The mass showed strong homogeneous contrast enhancement with well‐defined margins and had thickening of the adjacent meninges (dural tail sign). Based on MRI findings a malignant neoplastic process was considered most likely and the patient was placed on oral prednisone to decrease peri‐tumoral inflammation. The dog initially improved but was euthanized 3 weeks later for worsening clinical signs. Histopathologic assessment of the mass revealed marked pyogranulomatous optic neuritis with intralesional fungal yeasts consistent with blastomycosis (Blastomyces dermatitidis). To our knowledge this is the first report of invasion of a retrobulbar blastomycotic lesion into the calvarium in a dog.     

Disseminated mast cell tumor infiltrating the sphenoid bone and causing blindness in a dog

Mast cell tumors are found in most organs and tissues with variable biologic behavior in dogs. This case illustrates the clinical and magnetic resonance imaging (MRI) findings in a dog with disseminated mast cell tumor infiltrating the sphenoid bones. A 6‐year‐old male neutered Greyhound presented with a 3‐day history of acute onset of blindness. General physical examination was normal. Neurological examination revealed mildly disorientated mental status, absent menace response in both eyes, bilaterally decreased vestibulo–oculocephalic reflexes and absent direct and consensual pupillary light reflex in both eyes. An electroretinogram indicated normal retinal function in both eyes. A lesion involving the middle and rostral cranial fossa was suspected. Hematology and serum biochemistry were normal except decreased urea (1.2 mmol/L). MRI of the head revealed heterogeneous signal intensity of the sphenoid bones on T2‐weighted images and loss of their normal internal architecture. Cerebrospinal fluid analysis was normal. Abdominal ultrasound revealed hepatosplenomegaly and mesenteric lymphadenopathy. Fine needle aspirates were taken from the jejunal lymph nodes and the spleen. Results were consistent with disseminated mast cell tumor. The owner declined any treatment and the dog was euthanatized. Postmortem examination confirmed disseminated mast cell tumor affecting multiple organs, including the sphenoid bones. To our knowledge, this is the first case describing MRI features of disseminated mast cell tumor affecting the sphenoid bones and causing acute onset of blindness in a dog.     

Eosinophilic cerebrospinal fluid pleocytosis associated with neural Angiostrongylus vasorum infection in a dog

A 1‐year‐old, female intact Pug dog was presented to the Small Animal Teaching Hospital of the University of Liverpool with a 4‐week history of progressive multifocal intracranial signs. Magnetic resonance imaging (MRI) detected multiple hemorrhagic lesions in the brain. The Baermann and zinc sulfate flotation tests with centrifugation, performed on fecal samples, were positive for lungworm larvae and an antigenic test confirmed Angiostrongylus vasorum infection. Anthelmintic treatment was started with a consequent marked clinical improvement. Seventy days later, the dog was clinically normal, and no larvae were detected on the Baermann test. Repeat MRI of the brain revealed marked improvement of the hemorrhagic lesions. Cerebrospinal fluid analysis (CSF) showed marked eosinophilic pleocytosis, and anthelmintic treatment was restarted. A follow‐up CSF analysis 4 months after the first presentation revealed resolution of the eosinophilic pleocytosis. This is the first case report of marked eosinophilic pleocytosis associated with neural A vasorum infection in a dog. The CSF eosinophilic pleocytosis persisted for several weeks after treatment, even in the absence of concurrent clinical signs and with a negative A vasorum Baermann test.     

PARTIAL ESOPHAGEAL OBSTRUCTION BY AN INTRAMURAL HEMATOMA IN A DOG

A 9-year-old male Beagle dog was presented with a history of regurgitation for more than a month. In radiographic examination of the esophagus, a space-occupying defect suggesting an intramural lesion was found in the caudal esophagus. At necropsy a diagnosis of a hematoma of the wall of the esophagus was made. Trauma was suggested as a possible etiology because the dog also had a fracture of the first rib on the same side as the esophageal hematoma.     

IMAGING DIAGNOSIS — MAGNETIC RESONANCE IMAGING OF INTRACRANIAL INFLAMMATORY FIBROSARCOMA IN A MIXED BREED DOG

An 8‐year‐old mixed‐breed dog presented with progressive behavioral changes and altered mentation. Magnetic resonance imaging (MRI) of the brain revealed an olfactory and frontal lobe extra‐axial mass. The mass exhibited the following MRI signal intensity characteristics: T2W mixed, T1W iso‐ to hypointense, FLAIR hyperintense, and strong contrast enhancement. The mass was removed with cavitronic ultrasonic surgical aspirator (CUSA) assisted neurosurgery. Based on histopathological appearance and immunohistochemistry, the diagnosis of inflammatory fibrosarcoma was made. To our knowledge, this is the first report describing MRI characteristics of intracranial inflammatory fibrosarcoma in the veterinary literature.     

Traumatic intracerebral hematoma in a dog: MR images and clinical findings

A nine-year-old, male, mongrel dog was unsteady after falling down a set of stairs. The dog exhibited a mildly abnormal gait 2 days after injury, and was not able to stand, with spasticity of the right limbs, 4 days after injury. MR imaging revealed a clearly demarcated mass on the top of the left lateral ventricle that showed mild hyperintensity on T1-weighted images and hyperintensity on T2-weighted images. The authors diagnosed the dog as having a traumatic intracerebral hematoma. This type of case, in which the clinical signs deteriorated due to edema associated with hematoma, is extremely rare.     

IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING OF DIFFUSE LEPTOMENINGEAL OLIGODENDROGLIOMATOSIS IN A DOG WITH “DURAL TAIL SIGN”

A case of diffuse leptomeningeal oligodendrogliomatosis affecting the brain and spinal cord of a dog is presented. A 7.5‐year old, male neutered Staffordshire bull terrier presented for evaluation of a chronic history of tetraparesis and seizures, with a multifocal neuroanatomical localization was determined. Extra‐axial intradural lesions with an atypical presentation of a dural tail sign were seen on MRI. Histologically, the lesions were consistent with leptomeningeal oligodendrogliomatosis. To the authors’ knowledge, a dural tail sign has not previously been reported as an MRI characteristic of diffuse leptomeningeal oligodendrogliomatosis in dogs.     

Incidence of Spinal Compressive Lesions in Chondrodystrophic Dogs with Abnormal Recovery after Hemilaminectomy for Treatment of Thoracolumbar Disc Disease: A Prospective Magnetic Resonance Imaging Study

Objective— To investigate causes of the lack of clinical improvement after thoracolumbar disc surgery. Study Design— Case–control magnetic resonance imaging (MRI) study. Animals— Chondrodystrophic dogs with acute thoracolumbar disc disease treated by hemilaminectomy: 10 that had no short‐term clinical improvement and 12 with “normal” clinical improvement. Methods— Dogs that had surgery for treatment of intervertebral disc extrusion (2003–2008) where thoracolumbar disc disease was confirmed by MRI were evaluated to identify dogs that had lack of clinical improvement after surgery. Ten dogs with delayed recovery or clinical deterioration were reexamined with MRI and compared with 12 dogs with normal recovery and MRI reexamination after 6 weeks (control group). Results— Of 173 dogs, 10 (5.8%) had clinical deterioration within 1–10 days after surgery. In 8 dogs, residual spinal cord compression was identified on MRI. Bleeding was present in 1 dog. In 3 dogs, the cause was an incorrect approach and insufficient disc material removal. In 3 dogs, recurrence occurred at the surgical site. In 1 dog, the centrally located extruded material was shifted to the contralateral side during surgery. These 8 dogs had repeat surgery and recovery was uneventful. In 2 dogs, deterioration could not be associated with a compressive disc lesion. Hemorrhagic myelomalacia was confirmed by pathologic examination in 1 dog. The other dog recovered after 6 months of conservative management. Conclusion— Delayed postsurgical recovery or deterioration is commonly associated with newly developed and/or remaining compressive disc lesion. Clinical Relevance— We recommend early MRI reexamination to assess the postsurgical spinal canal and cord, and to plan further therapeutic measures in chondrodystrophic dogs with delayed recovery after decompressive hemilaminectomy for thoracolumbar disc disease.     

Imaging characteristics and treatment of a penetrating brain injury caused by an oropharyngeal foreign body in a dog

A 4‐year‐old Border collie was presented with one episode of collapse, altered mentation, and a suspected pharyngeal stick injury. Magnetic resonance imaging (MRI) and computed tomography showed a linear foreign body penetrating the right oropharynx, through the foramen ovale and the brain parenchyma. The foreign body was surgically removed and medical treatment initiated. Complete resolution of clinical signs was noted at recheck 8 weeks later. Repeat MRI showed chronic secondary changes in the brain parenchyma. To the authors' knowledge, this is the first report of the advanced imaging findings and successful treatment of a penetrating oropharyngeal intracranial foreign body in a dog.