Detailed anatomic description of the lateral, transzygomatic approach to the middle fossa and rostral brainstem and its use in three dogs.

OBJECTIVE: To describe a craniectomy using a lateral, transzygomatic approach to the middle fossa and rostral brainstem, and to report clinical outcomes and complications in three dogs. ANIMALS: Two cadaver dogs and three client-owned dogs. Two of the client-owned dogs with middle fossa lesions, and one with a rostral brainstem lesion. METHODS: Two cadavers were used to describe the lateral, transzygomatic surgical approach to the middle fossa and rostral brainstem. The medical records of three dogs undergoing this surgical approach were reviewed for data on signalment, preoperative and postoperative neurological status, diagnostic imaging, surgical technique, complications, and outcome. RESULTS: Indications for this surgical approach included incisional biopsy (n = 1) and debulking surgery for brain lesions (n = 2). Definitive diagnoses were achieved in two cases, and tumor volume reduction in all cases. Two of the three dogs developed postoperative facial nerve paralysis ipsilateral to the surgical site, which resolved within 2 and 12 weeks after surgery. CONCLUSION: The lateral, transzygomatic approach provided useful access to ventrally located cerebral/skull base lesions in dogs without major complications.

Periodic discharges in veterinary electroencephalography-A visual review.

First described in human EEG over 60 years ago, there are very few examples of periodic discharges in the veterinary literature. They are associated with a wide variety of etiologies, both intracranial and systemic, making interpretation challenging. Whether these patterns are indicative of ictal, interictal, or postictal activity is a matter of debate and may vary depending on the clinical features in an individual patient. Periodic discharges have a repeated waveform occurring at nearly regular intervals, with varying morphology of individual discharges from simple sharp waves or slow waves to more complex events. Amplitudes, frequencies, and morphologies of the discharges can fluctuate, occasionally evolving, or resolving over time. This study presents a visual review of several veterinary cases with periodic discharges on EEG similar to those described in human EEG, and discusses the current known pathophysiology of these discharges.

Use of C-reactive protein concentration in evaluation of diskospondylitis in dogs.

BACKGROUND: C-reactive protein (CRP) is a positive acute phase protein that increases in many inflammatory conditions of dogs. Serum CRP concentration has important diagnostic and prognostic utility in humans with vertebral osteomyelitis. HYPOTHESIS/OBJECTIVES: To determine if a correlation exists between serum CRP concentration and clinical and magnetic resonance imaging (MRI) findings in dogs with diskospondylitis, and if CRP predicts prognosis. ANIMALS: Eighteen client-owned dogs with MRI diagnosis of diskospondylitis. METHODS: Retrospective study evaluating signalment, clinical signs, neurologic examination findings, white blood cell count, neutrophil count, serum globulin concentration, serum CRP concentration, radiographic findings, MRI findings, bacterial culture results, and outcome in dogs with diskospondylitis. RESULTS: Serum CRP concentration was significantly more sensitive than were fever and leukocytosis for predicting the presence of diskospondylitis. Serum CRP concentration was more sensitive than neutrophilia and hyperglobulinemia. No difference in serum CRP concentration was found between dogs with single or multiple lesions, nor between dogs with or without empyema, muscular involvement or spinal cord compression. No association was found between serum CRP concentration and positive bacterial culture. CONCLUSIONS AND CLINICAL IMPORTANCE: C-reactive protein is a sensitive, but nonspecific biomarker for diskospondylitis which may prove useful as an adjunctive diagnostic test in patients with suspicious clinical signs and may help predict prognosis.

Prevalence of electrographic seizure in dogs and cats undergoing electroencephalography and clinical characteristics and outcome for dogs and cats with and without electrographic seizure: 104 cases (2009-2015).

OBJECTIVE: To determine the prevalence of electrographic seizure (ES) and electrographic status epilepticus (ESE) in dogs and cats that underwent electroencephalography (EEG) because of suspected seizure activity and to characterize the clinical characteristics, risk factors, and in-hospital mortality rates for dogs and cats with ES or ESE. DESIGN: Retrospective case series. ANIMALS: 89 dogs and 15 cats. PROCEDURES: Medical records of dogs and cats that underwent EEG at a veterinary neurology service between May 2009 and April 2015 were reviewed. Electrographic seizure was defined as ictal discharges that evolved in frequency, duration, or morphology and lasted at least 10 seconds, and ESE was defined as ES that lasted ≥ 10 minutes. Patient signalment and history, physical and neurologic examination findings, diagnostic test results, and outcome were compared between patients with and without ES or ESE. RESULTS: Among the 104 patients, ES and ESE were diagnosed in 21 (20%) and 12 (12%), respectively. Seventeen (81%) patients with ES had no or only subtle signs of seizure activity. The in-hospital mortality rate was 48% and 50% for patients with ES and ESE, respectively, compared with 19% for patients without ES or ESE. Risk factors for ES and ESE included young age, overt seizure activity within 8 hours before EEG, and history of cluster seizures. CONCLUSIONS AND CLINICAL REVELANCE: Results indicated that ES and ESE were fairly common in dogs and cats with suspected seizure activity and affected patients often had only subtle clinical signs. Therefore, EEG is necessary to detect patients with ES and ESE.

Synovial myxoma in the vertebral column of a dog: MRI description and surgical removal.

A 12 yr old castrated male mixed-breed dog presented with a 2 wk history of progressive tetraparesis. Neurologic deficits included a short-strided choppy gait in the thoracic limbs and a long-strided proprioceptive ataxia in the pelvic limbs. Withdrawal reflexes were decreased bilaterally in the thoracic limbs. Signs were consistent with a myelopathy of the caudal cervical/cranial thoracic spinal cord (i.e., the sixth cervical [C] vertebra to the second thoracic [T] vertebra). A mass associated with the C6-C7 articular facet on the left side was identified on MRI of the cervical spinal cord. The lesion was hyperintense to spinal cord parenchyma on T2-weighted images, hypointense on T1-weighted images, and there was strong homogenous contrast enhancement. Significant spinal cord compression was associated with the lesion. The mass was removed through a C6-C7 dorsal laminectomy and facetectomy. Histopathology of the mass was consistent with a synovial myxoma of the articular facet. A postoperative MRI showed complete surgical resection. Albeit rare, synovial myxomas should be included in the list of differential diagnoses for neoplasms affecting the vertebral columns in dogs.

Use of continuous electroencephalography for diagnosis and monitoring of treatment of nonconvulsive status epilepticus in a cat.

CASE DESCRIPTION: A 10-year-old domestic shorthair cat was evaluated because of presumed seizures. CLINICAL FINDINGS: The cat had intermittent mydriasis, hyperthermia, and facial twitching. Findings of MRI and CSF sample analysis were unremarkable, and results of infectious disease testing were negative. Treatment was initiated with phenobarbital, zonisamide, and levetiracetam; however, the presumed seizure activity continued. Results of analysis of continuous electroencephalographic recording indicated the cat had nonconvulsive status epilepticus. TREATMENT AND OUTCOME: The cat was treated with phenobarbital IV (6 mg/kg [2.7 mg/lb] q 30 min during a 9-hour period; total dose, 108 mg/kg [49.1 mg/lb]); treatment was stopped when a burst-suppression electroencephalographic pattern was detected. During this high-dose phenobarbital treatment period, an endotracheal tube was placed and the cat was monitored and received fluids, hetastarch, and dopamine IV. Continuous mechanical ventilation was not required. After treatment, the cat developed unclassified cardiomyopathy, azotemia, anemia, and pneumonia. These problems resolved during a 9-month period. CLINICAL RELEVANCE: Findings for the cat of this report indicated electroencephalographic evidence of nonconvulsive status epilepticus. Administration of a high total dose of phenobarbital and monitoring of treatment by use of electroencephalography were successful for resolution of the problem, and treatment sequelae resolved.

Diagnosis of rapid eye movement sleep disorder with electroencephalography and treatment with tricyclic antidepressants in a dog.

A 9-month-old, female Labrador retriever mix was presented for two types of seizure-like episodes, one of which occurred only during sleep. The two types of episodes were morphologically distinct. An electroencephalogram (EEG) demonstrated that the sleep-associated episodes occurred during rapid eye movement (REM) sleep, supporting a diagnosis of a REM behavior disorder. Based on their morphology and response to antiseizure medications, the waking episodes were diagnosed as seizures. The animal was also diagnosed with an obsessive-compulsive and generalized anxiety disorder. The REM behavior disorder and anxiety-related behaviors improved with tricyclic antidepressant therapy.

Extradural spinal, bone marrow, and renal nephroblastoma.

A 1-year-old, female intact Shetland sheepdog presented with acute onset of neurological signs. Physical examination revealed a large abdominal mass. Neurological examination revealed multifocal disease with neck pain, short-strided forelimbs, and hind-limb paresis with loss of tail and anal tone. Blood work, imaging techniques, cytopathology, and histopathology led to a diagnosis of renal, bone-marrow, and extradural spinal nephroblastoma. This report documents potential clinical and pathological manifestations of canine nephroblastoma that have not been previously reported.

Intravascular lymphoma involving the central and peripheral nervous systems in a dog.

A 5-year-old, castrated male mixed-breed dog was presented for paraparesis, ataxia, hyperesthesia, and thrombocytopenia of 5 months' duration and recurrent seizures during the preceding 2 weeks. Multifocal neurological, ophthalmological, pulmonary, and cardiac diseases were identified. Magnetic resonance imaging and cerebrospinal fluid analysis supported a tentative diagnosis of neoplastic or inflammatory disease. A computed tomography-guided biopsy provided both cytopathological and histopathological evidence of intravascular lymphoma. The disease progressed despite chemotherapy with prednisone, L-asparginase, and vincristine. Postmortem histopathological examinations suggested intravascular lymphoma in the central and peripheral nervous systems as well as in multiple other organ systems. This is the first description of an antemortem diagnosis and treatment of intravascular lymphoma involving the central nervous system of a dog.

Trigeminal neuropathy in dogs: a retrospective study of 29 cases (1991-2000).

The medical records of 29 dogs unable to close their mouths due to flaccid paralysis or paresis of the muscles innervated by the mandibular branch of the trigeminal nerve, were reviewed. Idiopathic trigeminal neuropathy was diagnosed in 26 dogs based on complete resolution of clinical signs and lack of any long-term neurological disease. Of these dogs, golden retrievers were overrepresented. No age, sex, or seasonal predispositions were identified. Trigeminal sensory innervation deficits were observed in 35% (9/26), facial nerve deficits were observed in 8% (2/26), and Horner's syndrome was observed in 8% (2/26) of dogs. Electromyographic examination of the muscles of mastication revealed abnormalities in seven of nine dogs. Results of cerebrospinal fluid analysis were abnormal in seven of eight dogs. Corticosteroid therapy did not affect the clinical course of the disease. Mean time to recovery was 22 days. Lymphosarcoma, Neospora caninum infection, and severe polyneuritis of unknown origin were diagnosed in three of 29 dogs at necropsy.

Results of cerebrospinal fluid analysis, neurologic examination findings, and age at the onset of seizures as predictors for results of magnetic resonance imaging of the brain in dogs examined because of seizures: 115 cases (1992-2000).

OBJECTIVE: To determine whether neurologic examination findings, results of CSF analysis, or age at the onset of seizures could be used to predict whether results of magnetic resonance imaging (MRI) would be normal or abnormal in dogs with seizures. DESIGN: Retrospective study. ANIMALS: 115 dogs. PROCEDURE: Information on results of neurologic examination, results of CSF analysis, age at the onset of seizures, and results of MRI was obtained from the medical records. RESULTS: Results of MRI were abnormal in 61 dogs and normal in 54. Sensitivity and specificity of neurologic examination alone were 77 (47/61) and 91% (49/54), respectively. Sensitivity and specificity of CSF analysis alone were 79 (48/61) and 69% (37/54), respectively. Results of MRI were abnormal for 12 of 28 (43%) dogs with abnormal CSF analysis results and normal neurologic examination results but for only 2 of 35 (6%) dogs with normal CSF analysis and normal neurologic examination results. Similarly, results of MRI were abnormal for 36 of 37 (97%) dogs with abnormal CSF analysis and abnormal neurologic examination results but for only 11 of 15 (73%) dogs with normal CSF analysis results and abnormal neurologic examination results. Age at the onset of seizures (< 6 vs > or = 6 years old) was not significantly associated with results of MRI. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that neurologic examination findings and results of CSF analysis are useful in predicting whether results of MRI will be abnormal in dogs examined because of seizures, but age at the onset of seizures is not.