Percutaneous recording of evoked spinal cord potentials of dogs.

Using a signal-averaging system, potentials evoked by stimulation of nerves in the limbs or tail of dogs were recorded through needle electrodes placed adjacent to the vertebral column. Cord dorsum potentials (consisting of a small triphasic wave followed by a large negative peak and a subsequent slow positive phase) were recorded at the level of the lumbar enlargement after stimulating nerves in the pelvic limb or tail, and at the cervical enlargement after forelimb nerve stimulation. Ascending volleys were recorded from appropriate levels of the spinal cord or from regions of the cauda equina. After forelimb nerve stimulation, a large slow potential, reflecting activation of an unidentified neuronal pool, was recorded at the level of the first cervical vertebra. Percutaneously recorded potentials were closely similar to those recorded directly from the dura mater, suggesting that the method accurately recorded spinal cord electrical events and, therefore, might be of use in studying clinical or experimental spinal cord disease.     

Cervical spinal chordoma with chondromatous component in a dog

A 7-year-old male Belgian Shepherd dog was presented with sudden onset of lateral recumbency and tetraparesis. At the level of the third cervical vertebra, magnetic resonance imaging demonstrated an intrameningeal and intramedullary mass lesion. The animal was subsequently euthanatized. A necropsy revealed a semitranslucent solid mass infiltrating dorsal and ventral dura mater and the spinal cord. Histologic examination revealed a lobulated pleomorphic mass, mainly resembling undifferentiated cartilage interspersed by spindle-shaped and polygonal cells with highly vacuolated cytoplasm (physaliphorous cells). Immunohistochemistry of the tumor cells demonstrated dual expression of vimentin and cytokeratin. Based on the histologic and immunohistochemical results, the diagnosis of a chordoma with chondromatous component was made.     

A case report of traumatic neuroma of the cervical spinal cord in a dog

Traumatic neuroma of the cervical spinal cord was diagnosed in a 14-year-old male mixed-breed dog. A gross view showed two intradural extramedullary masses, measuring 1 and 0.6 cm in length and 0.7 and 0.4 cm in diameter, attached to the left side of the spinal cord at the level of the sixth and seventh cervical vertebrae. Microscopically, the cervical spinal masses comprised interlacing fascicles of axons and Schwann cells surrounded by collagenous stroma. Immunohistochemically, the fascicles were stained positively for neurofilament and S-100 proteins. Ultrastructurally, variably sized myelinated fibers and onion bulb-like structures were observed. To our knowledge, this is the first report of a traumatic neuroma in the cervical spinal cord of a dog.     

Spinal cord astrocytoma in a cat

A nine-year-old neutered male domestic shorthaired cat with a history of spinal pain and progressive hindlimb dysfunction was presented to the Norwegian School of Veterinary Science. Following neurological and myelographic examination, an intramedullary mass affecting several lumbar spinal cord segments was diagnosed. A neoplastic lesion was suspected and a poor prognosis was given. On postmortem examination, the spinal cord was found to be dorsally flattened from the 12th thoracic vertebra to the fifth lumbar vertebra and severely thickened with a dorsal cleft from the fifth to the seventh lumbar vertebra. Histologically, the tumour was diagnosed as an anaplastic astrocytoma.     

Movement associated reduction of spatial capacity of the equine cervical vertebral canal

Laterolateral radiographs of equine necks are reported to be inaccurate in determining the site of spinal cord lesions even when a myelogram is carried out. The goal of this study was to assess constrictions present in the cervical vertebral canal at any time point throughout the extremes of movement. Sixteen equine cervical vertebral columns without history of cervical disease were used. After removal of the spinal cord, the dura mater was filled with polyurethane foam and during its plastic phase the cervical vertebral column was passively moved in flexion-extension, lateral bending and 30° rotated flexion and extension. Resulting moulded foam structures were scanned with a 3D laser scanner. Functional narrowing of the vertebral canal was located in the dorsolateral or ventrolateral regions, explaining its under-representation on laterolateral radiographs.     

Marsupialisation of an arachnoid cyst in a dog

A seven-month-old West Highland white terrier was presented with hindlimb ataxia and paraparesis. Radiographic studies revealed an arachnoid cyst at thoracic vertebrae 12 and 13. A dorsal laminectomy and durotomy were performed to decompress the spinal cord. The cyst was marsupialised by suturing the dura mater to the edge of the laminectomy defect. There were no postoperative complications and the dog improved to normality.     

INTRAOPERATIVE SPINAL ULTRASONOGRAPHY IN DOGS: NORMAL FINDINGS AND CASE-HISTORY REPORTS

Intraoperative spinal ultrasonography was performed in cervical and lumbar spine of 2 and 5 normal dogs, respectively, following ventral slot technique or dorsal or hemilamenectomy. The dura was hyperechoic, while the parenchyma was hypoechoic. The subarachnoid space was anechoic. An echogenic line was present in the center of the spinal cord, as seen in human. Pulsation of the spinal cord was noted during M-mode imaging. Clinical findings of one dog with thoracolumbar disk herniation and one with thoracic vertebral fracture/subluxation confirmed the usefulness of intraoperative spinal ultrasonography for real time evaluation of spinal canal spatial abnormalities (mass lesion and degree of spinal cord compression on scanning planes) and spinal cord motion. Follow-up ultrasound examinations were possible from 6 days postoperatively.     

Endoscopic anatomy of the cervical vertebral canal in the horse: a cadaver study

Reason for performing study: Localisation of spinal cord compression in horses with cervical vertebral stenotic myelopathy is inexact. Vertebral canal endoscopy has been used in man to localise spinal cord lesions and has the potential to become a useful diagnostic technique in horses. Objective: To establish a surgical approach via the atlanto‐occipital space to the cervical vertebral canal in equine cadavers and describe the endoscopic anatomy of the cervical epidural and subarachnoid spaces. Methods: The cadavers of 25 mature horses were used to assess 3 surgical methods to approach the cervical vertebral canal, including 2 minimally invasive and one open technique. Once the approach had been made, a flexible videoendoscope was inserted into the epidural space (epiduroscopy) or the subarachnoid space (myeloscopy) and advanced caudally until the intervertebral space between C7 and T1 was reached. Results: The epidural and subarachnoid spaces could not be accessed reliably using the minimally invasive techniques. Furthermore, damage to the nervous tissues was a frequent complication with these procedures. The open approach allowed successful insertion of the videoendoscope into the epidural and subarachnoid spaces in all horses and no inadvertent damage was observed. Anatomical structures that could be seen in the epidural space included the dura mater, nerve roots, fat and the ventral internal vertebral venous plexus. In the subarachnoid space, the spinal cord, nerve roots, blood vessels, denticulate ligaments and external branch of the accessory nerve were seen. Conclusions: Using the open approach, epiduroscopy and myeloscopy over the entire length of the cervical vertebral canal are possible in the mature horse. Potential relevance: Cervical vertebral canal endoscopy may become a valuable tool to localise the site of spinal cord injury in horses with cervical vertebral stenotic myelopathy and could aid in the diagnosis of other diseases of the cervical spinal cord.     

Possible intraspinal metastasis of a canine spinal cord nephroblastoma

A 2-year-old Basset Hound was admitted to the University of Florida Veterinary Medical Teaching Hospital with progressive spastic paraparesis. At necropsy, intradural extramedullary tumors produced areas of spinal cord swelling and softening in spinal cord segments T11-T12 and L4-L6. Histologic examination of the masses revealed sheets of polygonal blastemal cells, epithelial cells forming tubules and rosettes, and embryonal glomeruloid-like structures in the thoracic mass. Cells in the lumbar mass were less differentiated, forming rare tubules and no glomeruloid-like structures. The occurrence of two tumors in the spinal cord along with the less differentiated appearance of the lumbar tumor raises the possibility that the lumbar mass arose as a result of intraspinal metastasis. To our knowledge, this is the first report of multifocal or metastatic canine spinal nephroblastoma. In addition, the vimentin and cytokeratin immunohistochemical staining characteristics of these spinal cord nephroblastomas are described.     

Spinal dural ossification causing neurological signs in a cat

A six-year-old Ragdoll cat underwent examination due to a six-month history of slowly progressive gait abnormalities. The cat presented with an ambulatory tetraparesis with a neurological examination indicating a C1-T2 myelopathy. Radiographs of the spine showed a radiopaque irregular line ventrally in the vertebral canal dorsal to vertebral bodies C3-C5. In this area, magnetic resonance imaging revealed an intradural extramedullary/extradural lesion compressing the spinal cord. The spinal cord was surgically decompressed. The cause of the spinal cord compression was dural ossification, a diagnosis confirmed by histopathological examination of the surgically dissected sample of dura mater. The cat gradually improved after the procedure and was ambulating better than prior to the surgery. The cat’s locomotion later worsened again due to ossified plaques in the dura causing spinal cord compression on the same cervical area as before. Oral prednisolone treatment provided temporary remission. Ten months after surgery, the cat was euthanized due to severe worsening of gait abnormalities, non-ambulatory tetraparesis. Necropsy confirmed spinal cord compression and secondary degenerative changes in the spinal cord on cervical and lumbar areas caused by dural ossification. To our knowledge, this is the first report of spinal dural ossification in a cat. The reported cat showed neurological signs associated with these dural changes. Dural ossification should be considered in the differential diagnosis of compressive spinal cord disorders in cats.     

Spontaneous Malignant T-cell Lymphoma in a Young Adult Crl:CD (SD) Rat

We investigated a case of spontaneous malignant T-cell lymphoma observed in a 19-week-old male Crl:CD (SD) rat. The rat showed paralysis beginning 1 week before euthanasia. Hematological examination revealed marked lymphocytosis without distinct atypia. Macroscopically, hepatosplenomegaly and partial atrophy of the thoracic spinal cord were observed. Microscopically, neoplastic cells infiltrated into the liver, splenic red pulp, bone marrow and epidural space of the thoracic spinal cord, while no neoplastic cells were observed in the thymus and lymph nodes. Moreover, the spinal cord showed focal degeneration due to compression by marked infiltration of neoplastic cells in the subdural space. The neoplastic cells were generally small-sized round cells that had a round nucleus with/without a single nucleolus and scanty cytoplasm. Immunohistochemically, the neoplastic cells were positive for CD3 and CD8 and negative for CD79α. Judging from these results, the present tumor in this young adult rat was diagnosed as malignant T-cell lymphoma.     

Computed tomographic evaluation of cervical vertebral canal and spinal cord morphometry in normal dogs

The height, width, and cross-sectional area of the vertebral canal and spinal cord along with the area ratio of spinal cord to vertebral canal in the cervical vertebra were evaluated in images obtained using computed tomography (CT). Measurements were taken at the cranial, middle, and caudal point of each cervical vertebra in eight clinically normal small breed dogs (two shih tzu, two miniature schnauzers, and four mixed breed), 10 beagles, and four German shepherds. CT myelography facilitated the delineation of the epidural space, subarachnoid space, and spinal cord except at the caudal portion of the 7th cervical vertebra. The spinal cord had a tendency to have a clear ventral border in the middle portion of the vertebral canal and lateral borders near both end plates. The height, width, and area of the vertebral canal and spinal cord in the cervical vertebra were increased as the size of dog increased. However, the ratio of the spinal cord area to vertebral canal area in the small dogs was higher than that of the larger dogs. Results of the present study could provide basic and quantitative information for CT evaluation of pathologic lesions in the cervical vertebra and spinal cord.     

Double vertebral injury in a calf (case report)

A double spinal cord trauma of an eight weeks old calf is reported, born on pasture from a heifer as a premature birth at the beginning of month 9. Observations made were rupture of intervertebral disk at the crossing of cervical to thoracic vertebrae followed by syndesmosis or synchondrosis resp., as well as a comminuted fracture of the 1st lumbar vertebra including both the adjoining vertebrae, with succeeding reactive callus formation. It is concluded that this traumatization has occurred during parturition. Motoric or sensory disturbances were observed neither.     

Motor Neuron Organization and Corticospinal Fibers in the Cervical Intumescence of the Raccoon (Procyon lotor) Spinal Cord

Experiments were performed on 19 raccoons to determine the organization of the spinal alpha motoneurons innervating the muscles of the thoracic limb. Chromatolysis of motoneurons was provoked by resecting major nerves or removing individual muscles or muscle groups. Proximal intrinsic limb muscle motoneurons were located cranially in the cervical spinal intumescence and distal muscle motoneurons more caudally. Flexor motoneurons were generally dorsal and more laterally located within the lateral motoneuronal cell group than were the cell bodies innervating their extensor antagonists. The distribution of motor cortex projections to motoneurons was studied in five raccoons by selective silver impregnation of degenerating fibers after unilateral motor cortex ablation. Degenerating cortical projections within the motoneuronal cell group (Rexed's lamina IX) were seen only in the more dorsal and the lateral portions in the seventh and eighth cervical and the first thoracic spinal cord segments. Motor cortex preterminal and terminal fibers were in close apposition to the proximal dendrites and the somata of alpha motoneurons innervating primarily the more distal limb musculature and particularly the intrinsic muscles of the manus.     

Dorsal Laminectomy in the Horse II. Evaluation in the Normal Horse

Subtotal dorsal cervical laminectomy was performed on nine normal horses to evaluate positioning, refine the surgical technique, and assess the immediate and long-term effects of this procedure in the horse. Funkquist type B laminectomies were performed at various levels from C3-C4 to C6-C7. Absorbable gelatin sponge or autogenous nuchal fat was placed over the exposed dura mater. Surgery times varied from 2 to 3 hours, and all horses recovered without complication. Rapid primary intention wound healing occurred, with two horses showing neck pain. All remained neurologically normal. The horses were euthanized 6 weeks, 3 months, or 6 months postoperatively. Myelograms performed just prior to euthanasia demonstrated normal or expanded dye column widths. Necropsy revealed that all surgical sites had healed well. The laminectomy membrane was soft and pliable and could be easily separated from the underlying dura mater when fat was used as interpositional material. When gelatin sponge was used, the laminectomy membrane was firmly bonded to the dura. Spinal cords at the level of laminectomy appeared normal and moved freely within the vertebral canal. Histological evaluation of the laminectomy sites and associated spinal cord revealed no abnormalities attributable to the surgery. It was concluded that dorsal cervical laminectomy can be performed in horses without untoward sequelae. The procedure may be useful for the treatment of equine cervical compressive myelopathies.     

Study on the Developmental Changes in Angulation of Spinal Nerves, the Length of the Dorsal Roots and Spinal Nerves in Sheep

This study reports the angulation of spinal nerves, the length of dorsal roots, the length of spinal nerves and the transverse and vertical diameters of the spinal cord during pre- and postnatal life in sheep of the Mehraban breed in Iran. The spinal cord of these animals was divided into 4 regions with respect to the angulation of spinal nerves. The first region was from the first to fifth cervical and the second was from the sixth cervical to the eighth thoracic in fetuses and from the six cervical to fourth thoracic in adults. The third region was from the ninth thoracic to second lumbar in fetuses and from the fifth thoracic to second lumbar in adults, and the fourth region was from third lumbar to fourth sacral in the animals of all age groups. The length of dorsal roots from their point of emergence from the spinal cord to the dorsal root ganglia showed a direct correlation with the length of the spinal nerves. While angulation of the spinal nerves showed a converse correlation with the length of either spinal nerves or dorsal roots. The transverse diameters of the spinal cord were always longer than the vertical diameters. The greatest diameters (vertical — 7.00 mm; transverse — 10.00 mm) are recorded at C1, T1 and L6 in adult sheep.     

Ganglioneuroma of the brachial plexus in two cockatiels (Nymphicus hollandicus)

Ganglioneuroma involving the brachial plexus, paraspinal ganglia, and cervical-thoracic spinal cord was diagnosed in 2 adult cockatiels (Nymphicus hollandicus). Both birds had a chronic 1-year history of ataxia and perching difficulty. At necropsy, each bird had a unilateral, firm, gelatinous white to tan multilobular mass at the thoracic inlet expanding and partially obliterating the brachial plexus and cervical spinal cord. Histologically, the masses were characterized by a locally infiltrative neoplasm comprised of spindloid cells forming streams and sheets with interspersed distinct neuron cell bodies consistent with ganglion cells. The spindloid cell population was immunohistochemically positive for neurofilament protein in one of the birds.     

Magnetic resonance imaging findings of a metastatic chemodectoma in a dog

A 6-year-old, male, Collie-cross was presented with a non-weight bearing right thoracic limb lameness, right m. deltoideus, m. infraspinatus and m. supraspinatus atrophy, and severe neck pain with spasm of the cervical epaxial muscles. MRI revealed complete destruction of the 5th and 6th cervical vertebral bodies with lateral extradural spinal cord compression at the level of the 4th and 5th cervical vertebrae. These lesions were very clearly demonstrated on magnetic resonance images, while only subtle changes were seen on survey radiographs. Post mortem investigation revealed a large heart base chemodectoma with multiple smaller tumours in the cranial mediastinum and a single tumour nodule on the thoracic aorta. The 5th cervical vertebral body had necrotic, haemorrhagic and lytic changes. Histopathology of the heart base tumour, the nodules in the cranial mediastinum and on the thoracic aorta and samples from the 5th cervical vertebra confirmed the presence of a malignant aortic or carotid body tumour originating from the chemoreceptor organs. Diagnostic imaging features and post mortem findings are described. To our knowledge, this is the first report of the magnetic resonance features of a metastatic chemodectoma in a dog.     

Role of transcranial magnetic stimulation in differentiating motor nervous tract disorders from other causes of recumbency in four horses and one donkey

Transcranial magnetic stimulation and measurement of the magnetic motor-evoked potentials (MMEPs) in the thoracic and pelvic limbs of four recumbent horses and one recumbent donkey were used to assess the integrity of the descending motor pathways, in order to confirm or exclude a descending motor tract lesion as the cause of the recumbency. In two of the animals abnormal MMEPs were recorded; in one of the horses a lesion along the cervical spinal cord due to a fracture of the fifth cervical vertebra was diagnosed and confirmed by radiography and postmortem examination; in another horse, damage to the peripheral nerves of the left forelimb was diagnosed and confirmed postmortem when a large abscess was found to have been compressing the peripheral nerves at the level of the last cervical vertebra. In the three other animals, normal MMEPs were recorded, and laminitis, rhabdomyolysis and physitis were diagnosed as the causes of the recumbency.