Biomedical subjects
Publications and source records attributed to J T Robertson.
A grade-4 rectal tear in a mare was successfully repaired per rectum, using a surgical stapling device. The mare had only minor postoperative complications. This technique has some advantages over previously described procedures, but should be reserved for use in selected cases.
Ischemic optic neuropathy accompanied by blindness was induced in 2 horses after surgical occlusion of the external and internal carotid and greater palatine arteries, performed as part of the management of guttural pouch mycosis. The blindness was acute and unilateral and may have been caused by ischemic retinal damage. Vascular occlusion is a recommended procedure for treatment of guttural pouch mycosis. Retinal damage and blindness are a possible complication if all possible sources of hemorrhage are occluded.
Congenital frontal sinus cysts were found bilaterally in the frontal sinuses of a one-year-old miniature horse. Diagnosis was based on radiography of the head and cytologic examination of tissue aspirated from the frontal sinuses. The cysts were surgically removed, using a hinged bone flap technique bilaterally over the frontal sinuses.
An approach to tumors of the middle compartment of the skull base is described with three case reports. It is accomplished by extending the subtotal maxillectomy or maxillotomy to include removal of a part of the malar bone, coronoid process of the mandible, nasal turbinates, ethmoid and sphenoid sinuses, posterior nasal septum, and pterygoid plates. Extension of the incision through the anterior tonsillar pillar and lateral pharyngeal wall into the retropharyngeal space will assist to expose the craniocervical region from the sphenoid roof to the fifth cervical vertebra and the skull base between each eustachian tube and carotid canal. The function of the trigeminal, facial, and hypoglossal nerves, hearing, and nasal airway are preserved without mastoidectomy. A temporalis muscle flap closes the defect. Dysphagia and aspiration are not handicaps.
The authors discuss the surgical treatment of selected diseases of the upper airway of the racehorse. Although most of these conditions occur commonly and are easily diagnosed, their surgical management is often less straight-forward and may be surprisingly controversial. The authors' intent is to provide an overview of these problems and give some information regarding current treatment options.
A comparison of the haemodynamic benefits of small volume hypertonic saline (2,400 mOsm/litre) versus isotonic saline (300 mOsm/litre) was conducted in 12 adult horses using a haemorrhagic shock model. The horses were anaesthetised and intravascular catheters placed for the measurement of haemodynamic data. Mean systemic arterial pressure was then reduced to 50 to 60 mmHg by controlled haemorrhage and maintained at that level for 40 mins. Cardiac output, stroke volume, mean systemic arterial pressure, plasma volume and urine production decreased significantly following blood loss. Hypertonic or isotonic saline was administered randomly by intravenous infusion and haemodynamic data recorded for a 2 h period. Treatment with hypertonic saline produced rapid elevations in cardiac output, stroke volume, mean systemic and pulmonary arterial pressures, cardiac contractility and urine output, and was accompanied by expansion of the plasma volume. The changes in cardiac output and stroke volume were maintained for the duration of the recording period, whereas increases in mean systemic arterial pressure were not as remarkable. Infusion of isotonic saline caused only transient increases in cardiac output and mean systemic and pulmonary arterial pressure, and cardiac output; urine output and plasma volume did not change. This study indicates that hypertonic saline produces haemodynamic improvements in experimentally induced haemorrhagic shock in horses.
The effects of treatment with small volume hypertonic (2400 mOsm/litre) and isotonic (300 mOsm/litre) saline on serum electrolyte and biochemical concentrations, haemograms and blood gases were evaluated in 12 horses using a haemorrhagic shock model. Intravascular catheters were placed surgically for sample collection prior to anaesthesia. Controlled haemorrhage was initiated and continued until mean systemic pressure reached 50 to 60 mmHg. Hypertonic or isotonic saline (2 litres) was administered by intravenous infusion and data collected for 2 h. Following haemorrhage, packed cell volume (PCV), haemoglobin, blood glucose concentrations and erythrocyte numbers increased whereas plasma total protein and albumin concentrations decreased. Infusion of hypertonic saline resulted in a further decrease in total protein and albumin concentrations. Glucose concentrations and other haematological variables were unaffected. Isotonic saline administration did not affect electrolyte, total protein or albumin concentrations. Concentrations of sodium and chloride were unaffected by hypotension but increased significantly following hypertonic saline treatment, exceeding normal values during the immediate post treatment period. Serum osmolality increased concurrently. No significant changes in arterial and venous blood gas values were observed with haemorrhage or isotonic saline treatment. A transient decrease in arterial and venous blood pH and a sustained decrease in venous bicarbonate and base excess concentrations occurred following hypertonic saline administration. No significant increases in any serum biochemical concentrations occurred during hypotension or following infusion of either isotonic or hypertonic saline. These results demonstrate that small volume hypertonic saline can be administered safely to horses without producing extreme changes in electrolyte concentrations, blood gases or haematological parameters.
Intervertebral disc degeneration of any etiology may be associated with the formation of spaces or clefts within the disc. Gas collects within these spaces and can be seen roentgenographically. A case is presented in which intradiscal gas herniated into a connective tissue capsule, displacing the left S-1 nerve root and producing symptoms and signs identical to those of a herniated nucleus pulposus. The pathophysiology of gas within a disc space and the possibility that it may herniate much like the nucleus pulposus is discussed.
Atresia coli was identified in 26 calves. In calves with abdominal distension, progressive depression, and the absence of feces since birth, atresia coli should be suspected. Surgery was performed on 24 calves, involving decompression of the distended large intestine followed by colonic anastomosis. Nine calves were subsequently discharged; 3 of those calves reached breeding age. As an adult, 1 of the calves produced 5 offspring unaffected by atresia coli. Early postoperative mortality was associated with hypothermia, peritonitis, and ischemic necrosis of the large intestine. Calves with visible signs of peritonitis at surgery had a poor prognosis. Four calves had motility disturbances of the colon after surgery. These were characteristic of a functional obstruction and were unresponsive to treatment. Surgery was most successful in calves that were bright, alert, and ambulatory.
Bone sarcomas are the most common second malignant neoplasms in survivors of a malignant solid tumor in childhood. In contrast to de novo tumors, secondary bone cancers are typically associated with a poor prognosis, reflecting both a preponderance of primary sites that preclude complete resection in the flat bones of the axial skeleton, and the tendency for local invasiveness or distant metastasis. We describe a patient who developed malignant extradural osteosarcoma of the temporal bone 6 years after successful treatment for a malignant cerebellar astrocytoma with surgical resection and local irradiation. A complete resection of the sarcoma was not possible; however, she achieved a biopsy-proven complete response after intensive chemotherapy with ifosfamide, followed by cisplatin and doxorubicin. At age 13, she remains free of recurrence 3 years after completing all therapy. In view of the rarity of prolonged disease control after incomplete resection for osteosarcoma, this report suggests the value of intensive combination chemotherapy in achieving a durable unmaintained remission in our patient.
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In Brain Tumor Cooperative Group Study 77-02, eleven institutions randomized 603 adult patients with supratentorial malignant glioma to one of four treatment groups following surgery: conventional radiotherapy (6000 cGy in 30-35 fractions) + BCNU, conventional radiotherapy + streptozotocin, hyperfractionated (twice daily) radiotherapy (6600 cGy in 60 fractions) + BCNU, and conventional radiotherapy with misonidazole followed by BCNU. Data were analyzed for the total randomized population and for the 557 patients (86% with glioblastoma multiforme) who met protocol eligibility specifications (including confirmed histopathology on central review). Median survival was approximately 10 months following randomization. Overall there was no statistically significant difference in survival among the four groups. Among non-glioblastoma patients, the misonidazole group appeared to have poor survival. Peripheral neuropathy was a dose-limiting toxicity with misonidazole. It is concluded that neither the addition of misonidazole nor hyperfractionated radiotherapy as given in this protocol offered any advantage over conventional radiotherapy plus either BCNU or streptozotocin for treatment of malignant glioma.
This position statement provides guidelines for assessing risk associated with carotid endarterectomy and defines the point at which risk is too high to perform surgery for specific indications described below. Morbidity and mortality levels are discussed. This statement does not address indications for surgery or merits of specific medical or surgical treatments. Results of current studies that compare relative risk of various treatments for carotid artery disease are not yet available.
Within 3 weeks of definitive surgery, 571 adult patients with histologically confirmed, supratentorial malignant gliomas were randomly assigned to receive one of three chemotherapy regimens: BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea) alone, alternating courses (every 8 weeks) of BCNU and procarbazine, or BCNU plus hydroxyurea alternating with procarbazine plus VM-26 (epipodophyllotoxin). Patients accrued in 1980 and 1981 were to receive 6020 rads of whole-brain radiotherapy concurrent with the first course of chemotherapy. Patients accrued in 1982 and 1983 were randomly assigned to receive either whole-brain irradiation as above, or 4300 rads of whole-brain radiotherapy plus 1720 rads coned down to to the tumor volume. The data were analyzed for the total randomized population and separately for the 510 patients, termed the "Valid Study Group (VSG)," who met protocol eligibility specifications (including central pathology review), 80% of whom had glioblastoma multiforme. The median survival times from time of randomization for the three chemotherapy groups of the VSG ranged from 11.3 to 13.8 months, and 29% to 37% of the patients survived for 18 months (life-table estimate); the differences between these groups were not statistically significant. Survival differences between the radiotherapy groups were small and not statistically significant. It is concluded that, for malignant glioma, giving part of the radiotherapy by coned-down boost is as effective as full whole-brain irradiation, and that multiple-drug chemotherapy as outlined in this protocol conferred no significant survival advantage over BCNU alone.
Five foals were admitted because of colic that developed within 24 hours after birth. Physical examination revealed swelling from the inguinal region to the cranial aspect of the prepuce. Through the skin overlying the swelling, distended loops of bowel could be palpated. The hernias could be reduced with the foals restrained in dorsal recumbency. Surgical exploration showed the swelling to be an inguinal hernia with small bowel herniation through a rent in the common vaginal tunic. Concurrent rupture of the vaginal tunic should be suspected when a congenital inguinal hernia is associated with colic, swelling that extends to the prepuce, or intestine that is easily palpated within the hernial swelling. Repeated manual reduction in these cases would be of little benefit and surgical intervention would be recommended.
A 5-year-old Appaloosa mare had a history of mild intermittent abdominal discomfort and clinical signs that were suggestive of intestinal obstruction. Palpation per rectum revealed a large mass attached to the left uterine horn, with smaller masses extending dorsally and cranially and causing constriction of the rectum. At necropsy, numerous multilobulated masses were observed in the abdominal cavity and several nodules were seen in the lungs. The left ovary was large and contained both cartilage and hairlike material. Sections from all masses had similar histologic features and confirmed the tentative diagnosis of teratocarcinoma.
Functional obstruction of the right dorsal colon was found at surgery in a 6-year-old American Saddlebred gelding with a history of anorexia, depression, weight loss, and intermittent colic. Side-to-side anastomosis of the right dorsal colon to the small colon was done to bypass the obstruction. Histopathologic findings of the right dorsal colon and regional colonic lymph nodes were unremarkable. Surgical treatment was successful.
A urachal remnant, causing pollakiuria and dysuria, was diagnosed by rectal palpation of a urinary bladder adhesion and endoscopic visualization of a urinary bladder diverticulum. Surgical excision of the remnant resulted in relief of abnormal micturition, but the filly was euthanatized 9 months after surgery because of a chronic ventral midline incisional infection. Pollakiuria and dysuria associated with urachal abscessation occur most commonly in calves. This report documents the syndrome in a horse.