Imaging diagnosis--magnetic resonance imaging findings of primary cerebral hemangioma.

Intracranial hemangioma is a rare intraaxial hemorrhagic neoplasm with imaging characteristics similar to other intracranial hemorrhagic lesions. We describe two canine cerebral hemangiomas that appeared as poorly circumscribed intraaxial compressive lesions that were predominantly hypointense on T2 sequences and heterogeneously contrast enhancing. Both lesions had perilesional edema and were hypointense on T2(*) -gradient recalled echo sequences, consistent with hemorrhage. In one tumor a short partial peripheral rim was present, which was suggestive of hemosiderin deposition. Cerebral hemangioma should be included as a differential for hemorrhagic intracranial lesions.

Use of a selective serotonin reuptake inhibitor for treatment of episodes of hypertonia and kyphosis in a young adult Scottish Terrier.

CASE DESCRIPTION: A 2.5-year-old 12.4-kg (27.3-lb) castrated male Scottish Terrier was evaluated because of episodes of hypertonia and kyphosis for which a presumptive diagnosis of so-called Scottie cramp had been made when the dog was a puppy. CLINICAL FINDINGS: Findings of general physical, orthopedic, and neurologic examinations were within reference limits. Pelvic limb hypertonicity and kyphosis without signs of pain were induced with minimal exercise; ambulation returned to normal after a period of rest. TREATMENT AND OUTCOME: Fluoxetine, a selective serotonin reuptake inhibitor, was administered orally at a dosage of 1.2 mg/kg (0.55 mg/lb) once daily for 1 month. After this period of treatment, clinical signs of the disease were greatly reduced; the dosage of fluoxetine was changed to 0.8 mg/kg (0.36 mg/lb) twice daily, and response to treatment continued. CLINICAL RELEVANCE: Administration of benzodiazepines, vitamin E, or phenothiazines has been recommended for treatment of episodes of hypertonicity, but often does not result in control of clinical signs. It has been suggested that the pathogenesis of this disease is related to deficiencies in concentration or function of serotonin in the CNS; thus, a logical choice for treatment is administration of a serotonin reuptake inhibitor. In the dog of this report, fluoxetine resulted in good control of clinical signs. The use of an effective medication (other than a controlled substance) that is administered once or twice daily, has minimal adverse effects on the patient's mental status, and is inexpensive may lead to better owner compliance and an improved quality of life for affected dogs.

Use of an endoscope in minimally invasive lesion biopsy and removal within the skull and cranial vault in two dogs and one cat.

CASE DESCRIPTION- 2 dogs and 1 cat underwent endoscopic-assisted intracranial procedures for lesion biopsy (1 dog and 1 cat) and definitive lesion removal (1 dog). CLINICAL FINDINGS- 1 cat was treated for an interhemispheric, pedunculated meningioma with an associated arachnoid cyst. Two dogs underwent endoscopic surgery procedures; 1 dog underwent removal of an intranasal dermoid cyst with extension to the olfactory bulb dura, and the other underwent lesion biopsy for histologic confirmation of suspected intracranial granular cell tumor. TREATMENT AND OUTCOME- Minimally invasive intracranial procedures were achieved by use of an endoscope to aid in lesion biopsy in a dog and a cat with neoplasia and complete lesion removal in 1 dog with a dermoid cyst. No obvious morbidity from the use of the endoscope was observed. Rapid recovery from surgery was seen in all 3 animals, and hospitalization times were a few days. CLINICAL RELEVANCE- In human and veterinary neurosurgery, minimally invasive surgical approaches for diagnosis and treatment are gaining in popularity. Minimally invasive techniques are used to achieve a decrease in surgical time, minimize brain exposure, and decrease postoperative recovery times. Keyhole and minimally invasive approaches require some degree of dexterity and knowledge of where the endoscope is in a 3-dimensional orientation and its relationship to the topography of an anatomic region. Anticipation of complications should allow for potential conversion to an open craniotomy. Use of the endoscope in minimally invasive procedures is associated with a steep learning curve to understand orientation, topography, and normal versus abnormal anatomy.

Bioresorbable film for the prevention of adhesion to the anterior spine after anterolateral discectomy.

BACKGROUND CONTEXT: The development of scar tissue and adhesions postoperatively is a natural consequence of healing but can be associated with medical complications and render reoperation difficult. Many biocompatible products have been evaluated as barriers or deterrents to adhesions. PURPOSE: To evaluate the efficacy of a bioresorbable polylactide film as a barrier to adhesion formation after anterolateral discectomy. STUDY DESIGN: Experimental study. METHODS: Seven, skeletally mature female sheep underwent a retroperitoneal approach to the anterolateral lumbar spine. A discectomy was performed at two levels with an intervening unoperated disc site. One site was treated with a polylactide film barrier (Hydrosorb Shield; MacroPore Biosurgery, San Diego, CA) affixed with tacks manufactured from the same material. The second site was left untreated. Treatment and control sites were randomly assigned. Postmortem analysis included scar tenacity scoring on five spines and histological evaluation on two spines. RESULTS: The application of the Hydrosorb film barrier allowed a definite dissection plane during scar tenacity scoring and there was a significant difference in the development of adhesions to the disc between the control and treated sites. Histological evaluation revealed evidence of barrier formation to scar tissue and no significant adverse inflammatory reactions. CONCLUSIONS: Hydrosorb Shield appears to be an effective postoperative barrier to scar tissue adhesion after anterolateral discectomy. The use of polylactide tacks was beneficial to affix the barrier film in place. Safety issues associated with delayed healing or adverse response to the film or tacks were not observed. Hydrosorb film may be useful as an antiadhesion barrier facilitating dissection during surgical revision in anterior approaches to the spine. Further studies are indicated to evaluate the performance of the bioresorbable material as an antiadhesion barrier in techniques of spinal fusion and disc replacement.

Comparison of a caprolactone/lactide film (mesofol) to two polylactide film products as a barrier to postoperative peridural adhesion in an ovine dorsal laminectomy model.

STUDY DESIGN: Experimental study. OBJECTIVE: To evaluate and compare the performances of 2 bioresorbable products, Mesofol (a caprolactone/lactide film) and Lactosorb (a polylactide film), as barriers to postoperative peridural adhesions and fibrosis. SUMMARY OF BACKGROUND DATA: Postoperative peridural adhesions from scar tissue may be an inciting cause of chronic pain and dysfunction in "failed back" syndrome. Many biocompatible products and drugs, as well as autografts have been tested as antiadhesion barriers with varying success. METHODS: The bioresorbable film products were used to cover large laminectomy defects in 11 sheep. Three laminectomy defects were created, with 2 randomly assigned treatment sites and 1 control site in each animal. A tear was created in the dura allowing cerebrospinal fluid leakage to assess for impaired dural healing. Performance of the film barriers was assessed at 10 weeks postoperative by gross scar and tenacity scoring by 3 blinded, independent observers in 7 animals. Histology was performed in 4 animals. New Methylene blue dye myelography and magnetic resonance imaging were performed to assess for cerebrospinal fluid leakage. Magnetic resonance imaging was also used to evaluate the imaging characteristics of adhesions. RESULTS: All 3 products evaluated showed a benefit to prevention of postoperative peridural adhesion; the performance of Mesofol was deemed superior to either of the 2 Lactosorb products. The handling characteristics of all products were compatible with clinical usage. Impairment to healing of dural tears or active inflammation was not identified with any product. CONCLUSION: The results of this investigation support previous studies on the benefit of polylactide film barriers, like Lactosorb, for reducing peridural adhesion following spinal surgery. The performance of Mesofol in this investigation suggests that it may provide improved antiadhesion properties in comparison to the polylactide products. Safety issues related to impaired dural healing was not identified in either product.

Pulmonary edema induced by cerebral hypoxic insult in a canine model.

INTRODUCTION: The mechanisms of noncardiogenic pulmonary edema syndromes, such as neurogenic and high-altitude pulmonary edema, remain unclear even after years of study. Previous attempts to develop an animal model for these illnesses have used increased intracranial pressure or whole-body hypoxia. We hypothesized that a cerebral insult induced with a venous hypoxic blood infusion to the brain would trigger neurogenic pulmonary edema in a canine model. METHODS: We measured indices of pulmonary edema, hemodynamics, norepinephrine (NE), and epinephrine values in anesthetized adult Walker hounds in which the brain was perfused for 2 h with either venous blood (venous perfused brain, VPB) or arterial blood (arterial perfused brain, APB) while maintaining normoxic pulmonary and systemic circulations. Normal cerebral perfusion was then reinstated for an additional 2-h period before euthanasia. RESULTS: VPB animals showed a greater fall in arterial PO2 and SaO2 and higher peak plasma NE compared to APB. On necropsy, VPB animals had greater lungwet-to-dry weight ratios compared to APB. Histological analyses revealed areas of marked alveolar infiltration of neutrophils and macrophages, acute hemorrhage, congestion, and alveolar edema in the VPB animals. DISCUSSION: This study supports the hypothesis that a cerebral insult from venous hypoxic blood can induce pulmonary edema. This method yields a promising approach to the study of noncardiogenic pulmonary edema syndromes.

Magnetic resonance imaging characteristics of peripheral nerve sheath tumors of the canine brachial plexus in 18 dogs.

Magnetic resonance imaging (MRI) examinations from 18 dogs with a histologically confirmed peripheral nerve sheath tumor (PNST) of the brachial plexus were assessed retrospectively. Almost half (8/18) had a diffuse thickening of the brachial plexus nerve(s), six of which extended into the vertebral canal. The other 10/18 dogs had a nodule or mass in the axilla (1.2-338 cm3). Seven of those 10 masses also had diffuse nerve sheath thickening, three of which extended into the vertebral canal. The majority of tumors were hyperintense to muscle on T2-weighted images and isointense on T1-weighted images. Eight of 18 PNSTs had only minimal to mild contrast enhancement and many (13/18) enhanced heterogeneously following gadolinium DTPA administration. Transverse plane images with a large enough field of view (FOV) to include both axillae and the vertebral canal were essential, allowing in-slice comparison to detect lesions by asymmetry of structures. Higher resolution, smaller FOV, multiplanar examination of the cervicothoracic spine was important for appreciating nerve root and foraminal involvement. Short tau inversion recovery, T2-weighted, pre and postcontrast T1-weighted pulse sequences were all useful. Contrast enhancement was critical to detecting subtle diffuse nerve sheath involvement or small isointense nodules, and for accurately identifying the full extent of disease. Some canine brachial plexus tumors can be challenging to detect, requiring a rigorous multiplanar multi-pulse sequence MRI examination.

A posterior tether for fusionless modulation of sagittal plane growth in a sheep model.

STUDY DESIGN: This was an in vivo and in vitro investigation of a minimally invasive posterior tether system for fusionless modulation of sagittal plane growth in an immature sheep model. OBJECTIVE: To determine whether fusionless modulation of spinal growth in the sagittal plane of an immature sheep model can be successfully performed. SUMMARY OF BACKGROUND DATA: Scheuermann's disease has been reported to affect 1% to 8% of the pediatric population. Varying degrees of spinal bone growth modulation has been successfully performed in the coronal plane of animal models. This represents the first attempt to modulate spinal growth in the sagittal plane in an animal model. Modulation of spinal growth in the sagittal plane may play a role in the treatment of pediatric kyphosis when brace treatment is unsuccessful. METHODS: There were nine immature sheep posteriorly tethered and five control animals, all with identical follow-ups. Pedicle screws were placed in adjacent vertebrae, bilaterally, at the thoracolumbar junction and the lower lumbar spine. Polyethylene cords were passed subcutaneously, and tensioned to 20 lbs. Tethers were released in four sheep at 6 months and four at 12 months. At 12 months and 2 weeks, all animals were sacrificed. RESULTS: At 13 months after surgery, the tethered groups had significantly less kyphosis and vertebral body wedging than the control group. In both the tethered groups, at 13 months after surgery, there was significantly less vertebral body wedging compared with the preoperative values. There was no evidence of facet arthropathy, but heterotopic ossification was seen in several specimens. Tethered spines had significantly less motion than control spines. Histologic evaluation demonstrated no detrimental results. CONCLUSIONS: Fusionless modulation of sagittal plane growth in an immature sheep model was successfully performed with changes in the overall sagittal profile of the instrumented segments and vertebral body wedging. Increased stiffness of the instrumented segments posttether release was thought to be related to heterotopic ossification. Results suggest that this may be a potential treatment for adolescents with Scheuermann's disease.

Imaging diagnosis: magnetic resonance imaging of a cervical wooden foreign body in a dog.

This article describes the discovery of a chronic cervical wooden foreign body ventral to the left transverse processes of the cranial cervical spine using magnetic resonance imaging (MRI) in a dog that presented with chronic neck pain and lameness. The dog did not exhibit dysphagia or chronic draining tracts, the most common signs of the presumed cause, that of a penetrating oropharyngeal foreign body. The foreign body itself was represented on MR images as an oval straight-edged core within an inflammatory tissue reaction. The wood was slightly hyperintense on T2- and isointense on T1-weighted images relative to muscle. Surrounding this was a more conspicuous contrast-enhancing reactive tissue rim that was hyperintense on all pulse sequences. Adjacent musculature also exhibited diffuse edema and contrast enhancement that extended around the left cervical vertebral transverse processes and local intervertebral nerve roots. The foreign body was found to be a wooden stick upon surgical removal. MRI is an excellent method for visualizing the inflammatory tissue reactions associated with soft-tissue foreign bodies because of its contrast resolution and depiction of anatomy in multiple imaging planes.

Use of polylactide resorbable film as a barrier to postoperative peridural adhesion in an ovine dorsal laminectomy model.

OBJECT: The purpose of this study was to evaluate the performance of a resorbable polylactide film in the sheep posterior spine in the presence of a combined laminectomy and durotomy defect. METHODS: A resorbable polylactide film was used to cover the combined defects in the eight sheep used in this study. Two surgical levels were performed in each animal, with randomly assigned control and treated sites. Each surgical level consisted of a full laminectomy followed by a needle-induced durotomy. The treated levels received a resorbable polylactide film cut to size and tucked in under the laminar defect. At 8 to 10 weeks postoperatively, results of myelography and visual dye infiltration showed complete healing of the durotomies for all sites. In addition, evaluation of gross dissection based on volume and tenacity scores as well as histological findings indicates decreased posterior dural adhesions for sites treated with resorbable polylactide film. CONCLUSIONS: The results of this investigation support previous studies in which the use of a resorbable polylactide film was found to be effective in reducing posterior dural adhesions in the spine with no apparent safety issues related to impaired dural healing.