Temporal behavior of seizures and interictal bursts in prolonged intracranial recordings from epileptic canines.

OBJECTIVE: Epilepsy is a chronic disorder, but seizure recordings are usually obtained in the acute setting. The chronic behavior of seizures and the interictal bursts that sometimes initiate them is unknown. We investigate the variability of these electrographic patterns over an extended period of time using chronic intracranial recordings in canine epilepsy. METHODS: Continuous, yearlong intracranial electroencephalography (iEEG) recordings from four dogs with naturally occurring epilepsy were analyzed for seizures and interictal bursts. Following automated detection and clinician verification of interictal bursts and seizures, temporal trends of seizures, burst count, and burst-burst similarities were determined. One dog developed status epilepticus, the recordings of which were also investigated. RESULTS: Multiple seizure types, determined by onset channels, were observed in each dog, with significant temporal variation between types. The first 14 days of invasive recording, analogous to the average duration of clinical invasive recordings in humans, did not capture the entirety of seizure types. Seizures typically occurred in clusters, and isolated seizures were rare. The count and dynamics of interictal bursts form distinct groups and do not stabilize until several weeks after implantation. SIGNIFICANCE: There is significant temporal variability in seizures and interictal bursts after electrode implantation that requires several weeks to reach steady state. These findings, comparable to those reported in humans implanted with the NeuroPace Responsive Neurostimulator System (RNS) device, suggest that transient network changes following electrode implantation may need to be taken into account when interpreting or analyzing iEEG during evaluation for epilepsy surgery. Chronic, ambulatory iEEG may be better suited to accurately map epileptic networks in appropriate individuals.

Intervertebral disk disease in 3 striped skunks (Mephitis mephitis).

OBJECTIVE: To describe diagnostic findings, surgical technique, and outcome in 3 striped skunks (Mephitis mephitis) with a history of paraparesis. STUDY DESIGN: Case series. ANIMALS: Skunks (n = 3) with paraparesis. METHODS: Neurologic examination revealed upper motor neuron disease (T2-L2) in 2 skunks and lower motor neuron disease (L3-S3) in 1 skunk. Diagnostic imaging included radiography, myelography, CT, and MRI and confirmed intervertebral disk herniation (IVDH) in each skunk. Because initial treatment with pain medication and cage rest did not result in lasting improvement, spinal surgery was performed. RESULTS: Hemilaminectomy (2 skunks) and dorsal laminectomy (1 skunk) was performed with removal of extruded disk material. The skunks improved after surgery but all had minor residual neurologic deficits when examined at various times postoperatively. CONCLUSION: Thoracolumbar intervertebral disk herniation occurs in skunks, and must be included in the differential diagnosis of paraparesis.

Multiple meningiomas in three dogs.

Three dogs with seizures were diagnosed with multiple intracranial meningiomas. Two of the three dogs were golden retrievers, and ages ranged from 9 to 11 years. Treatment consisted of surgery and radiation (n=2) or chemotherapy (n=1). In all three cases, the masses were two distinct tumors as determined by imaging, surgery, or necropsy. In two dogs, the meningiomas had the same histological pattern, while in one dog the histological subtypes were different.

Evaluation of nonsurgical treatment of atlantoaxial subluxation in dogs: 19 cases (1992-2001).

OBJECTIVE: To evaluate long-term neurologic outcome in dogs with atlantoaxial subluxation (AAS) that were treated nonsurgically with a cervical splint. DESIGN: Retrospective study. ANIMALS: 19 dogs with AAS and managed with a cervical splint. PROCEDURE: Medical records from 2 university hospitals were reviewed. Information pertaining to trauma, duration of clinical signs prior to admission, medical treatments prior to admission, results of neurologic and physical examinations at the time of admission, results of laboratory testing, results of diagnostic imaging, neurologic status at the time of discharge, duration of time the cervical splint was used for treatment, and neurologic status at the time of splint removal and at a final reexamination was extracted from the medical records. Long-term outcome was defined as neurologic status greater than or equal to 1 year after splint removal. Factors associated with a good or poor long-term outcome were determined. RESULTS: A good final outcome was reported in 10 of 16 dogs. Median duration of clinical signs prior to referral was 30 days; dogs that were affected < or = 30 days were significantly more likely to have a good long-term outcome, compared with dogs affected > 30 days. The neurologic grade at admission, radiographic appearance of the dens, age at onset of clinical signs, and history were not associated with outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Nonsurgical management of AAS by use of a cervical splint is a viable treatment modality for young dogs with a first episode of acute-onset clinical signs, regardless of the severity of neurologic deficits at admission.

Thoracolumbar spinal cord compression due to vertebral process degenerative joint disease in a family of Shiloh Shepherd dogs.

Five young Shiloh Shepherd Dogs (4 males and 1 female) related by a common sire were studied because of progressive pelvic limb weakness and incoordination. All dogs had a spastic paraparesis and pelvic limb ataxia consistent with an upper motor neuron and general proprioceptive lesion between spinal cord segments T3 and L3. Proliferative lesions involving one or more of the articular processes from the 11th thoracic vertebrae to the 2nd lumbar vertebra were observed on radiographs of the thoracolumbar vertebrae. Dorsal compression of the spinal cord was identified during imaging studies at these sites. Abnormalities of the synovial joints and bony proliferation of the involved articular processes were identified at postmortem examination in 2 dogs. The articular processes and associated vertebral arches protruded into the vertebral canal, indenting the dorsal surface of the spinalcord. Degenerative joint disease (DJD) was identified histologically. A compressive myelopathy was diagnosed in the spinal cord. These dogs were affected by a compressive myelopathy as a consequence of vertebral process DJD that likely has a geneticcomponent. The DJD could have been caused by a primary vertebral malformation or an injury to the processes at a young age causing malarticulation.

Cytology of a mass on the meningeal surface of the left brain in a dog.

An 11-year-old neutered male Labrador Retriever presented to Tufts University School of Veterinary Medicine for a 2-week history of seizures and altered behavior. Magnetic resonance imaging (MRI) revealed a homogeneously enhancing mass involving the surface of the left temporal, parietal, and occipital lobes of the brain, causing secondary hydrocephalus. Cytology samples obtained during rostrotentorial craniectomy contained abundant amorphous pink material suggestive of neuropil, scattered leukocytes, capillary fragments, large polyhedral nerve cell bodies, and other smaller cells with pale blue cytoplasm that occasionally were vacuolated and contained fine eosinophilic granules. The cytologic diagnosis was neoplasia, possibly meningioma. Ninety days after surgery the patient was euthanized after MRI results confirmed regrowth of the tumor. Histologic samples of the meningeal lesion collected at necropsy consisted of sheets and nests of loosely packed, large polygonal cells that compressed the brain parenchyma. The cytoplasm was eosinophilic and slightly granular, whereas nuclei were dense and eccentric. Neoplastic cells stained positive for S-100 protein, periodic acid-Schiff, and were partially diastase resistant. Vimentin staining was negative. Ubiquitin staining was light but diffusely positive. Ultrastructural features of the neoplastic cells included numerous secondary lysosomes and irregular pleomorphic nuclei. The final diagnosis was meningeal granular cell tumor. This case documents the cytologic and histologic features of an uncommon type of meningeal tumor.

Evaluation of matrix metalloproteinase-2 and -9 in the cerebrospinal fluid of dogs with intracranial tumors.

OBJECTIVE: To identify matrix metalloproteinase (MMP)-2 and -9 in CSF from dogs with intracranial tumors. SAMPLE: CSF from 55 dogs with intracranial tumors and 37 control dogs. PROCEDURES: Latent and active MMP-2 and -9 were identified by use of gelatin zymography. The presence of MMPs in the CSF of dogs with intracranial tumors was compared with control dogs that were clinically normal and with dogs that had idiopathic or cryptogenic epilepsy or peripheral vestibular disease. Relationships between MMP-9 and CSF cell counts and protein were also investigated. RESULTS: Latent MMP-2 was found in CSF samples from all dogs, although active MMP-2 was not detected in any sample. Latent MMP-9 was detected in a subset of dogs with histologically documented intracranial tumors, including meningiomas (2/10), gliomas (3/10), pituitary tumors (1/2), choroid plexus tumors (5/6), and lymphoma (4/4), but was not detected in any control samples. Dogs with tumors were significantly more likely than those without to have detectable MMP-9 in the CSF, and the presence of MMP-9 was associated with higher CSF nucleated cell counts and protein concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Latent MMP-9 was detected in most dogs with choroid plexus tumors or lymphoma but in a smaller percentage of dogs with meningiomas, gliomas, or pituitary tumors. Detection of MMP in CSF may prove useful as a marker of intracranial neoplasia or possibly to monitor response of tumors to therapeutic intervention.

Magnetic resonance imaging features of cervical spinal cord meningiomas.

The records of four dogs with cervical spinal cord meningiomas were retrospectively reviewed. Signalment, history, laboratory findings, neurological examination, and histopathological findings were evaluated. Magnetic resonance imaging (MRI) was performed using a 1.0-T superconducting magnet and T2-weighted (W) and noncontrast and postcontrast T1-W spin echo pulse sequences. Meningiomas were located at the level of the second, third, and fifth cervical vertebrae and the C2-3 intervertebral space. All meningiomas appeared as focal masses that were hyperintense to the spinal cord on T2-W images and iso- to hypointense on the T1-W images. They could be identified as intradural and extramedullary in origin based on a broad-based dural margin seen on at least one of the imaging planes and a gradual expansion of the subarachnoid space cranial and caudal to the mass, best noted on the transverse and dorsal plane images. On dorsal plane T2-W images in three dogs, expansion of the subarachnoid space adjacent to the mass appeared similar to the myelographic "golf tee" sign. All meningiomas exhibited moderate, well-defined contrast enhancement with dural tails seen in three of the four dogs. One dog had extension into the intervertebral foramen along the nerve and ipsilateral atrophy of the muscles of the neck. By differentiating the meningiomas from intramedullary tumors and by clearly depicting the extent of the masses, MRI provided valuable information about treatment options and prognosis.