Effects of lumbar myelography on subarachnoid pressure and cardiorespiratory parameters in healthy sheep

ABSTRACT: The purpose of this study was to evaluate the effects of lumbar myelography on subarachnoid pressure, cardiorespiratory parameters and pressure-volume index in sheep. Eight sheep were evaluated. The animals were submitted to puncture of the cisterna magna for monitoring of subarachnoid pressure (SaP). Lumbar myelography was performed through applying Iohexol (0.4mL/kg). ToC, PAS, PAD, MAP, InspISO, FeISO, SaP and CPP were recorded immediately after anesthetic stabilization (M0), during lumbar puncture (M1), and two, four and six minutes after contrast application (M2, M3 and M4, respectively). Blood pressure initially increased, then decreased, returning to basal level, similarly observed for InspISo and FeISo. The SaP rose initially thereafter remaining stable. Despite of the effect on subarachnoid pressure, lumbar myelography can be considered safe in sheep.

Lumbar Myelography in a Crab-Eating Raccoon (Procyon cancrivorus)

Background: The Crab-eating raccoon (Procyon cancrivorus) is a nocturnal mammal and lives in savannah, but loss of their natural habitat makes increase cases of traffic accidents on the roads. A growing number of wildlife are treated in veterinary hospitals, but we have some limitation about the correct interpretation of the diagnostic test, specially because, even the tests were not described. Myelography is a radiographic technique indicated for compressive lesions of the spinal cord that are not seen on plain radiographs. The present report aims to describe, for the first time, a lumbar myelogram performed in a paraplegic crab-eating raccoon after it suffer a traffic trauma.Case: A free living adult, 8-kg, female raccoon was presenting acute paraplegia and swelling in the region of the left humerus was referred at veterinary hospital. The patient was alert and aggressive, good body score and no signs of active bleeding. The animal temper did not allow approaching it; therefore, physical and neurological examinations were not feasible. The raccoon was tranquilized (1.6 mL of nilperidol® intramuscular), anesthetized (propofol, dose-effect intra­venous) and tracheal intubation to provide oxygen and the patient was monitored continuously, followed by referred for radiology service. The simple radiograph showed a complete transverse fracture in the humerus and compression fracture of the twelfth thoracic vertebra (T12), being then indicated the myelographic examination to assess the extent of spinal cord compression. The lumbar region was surgical antisepsis prepared. After being properly positioned in lateral decubitus with moderate cranial flexion of the trunk, the patient underwent lumbar puncture by inserting a spinal needle between the 5th and 6th intervertebral lumbar spaces. The spinal needle was introduced slightly caudolaterally to the spinous process of the 6th lumbar vertebra and cranioventrally directed at an angle of 45º. Then, the needle was pierced through the ligamentum flavum and the dura mater while, concomitantly, we observed the tail moving and the cerebrospinal fluid (CSF) output while the contrast was injected. The contrast iohexol (300 mg/mL) was used at a dose of 0.25 mL/kg. Immediately after the slow injection of contrast (approximately 3 min), radiographs were taken in the latero-lateral and ventrodorsal projections to identify the location of the spinal cord disorder. The extension degree of the lesion was evidenced by the reduction of the contrast column width at the location of instability. The patient was referred for surgical decompression and stabilization.Discussion: In cases where paraplegia results from trauma, spinal radiography and myelography are important means to confirm the diagnosis, specially the extent of the compression and prognosis. There are certain risks inherent in the myelography procedure as arrhythmias and bradycardia during collection, transient apnea during contrast injection and seizures during recovery. Furthermore, deteriorating neurological signs, emesis, urinary retention and hyperthermia are other possible complications. Most of these complications are seen predominantly during cervical myelography compared to lumbar puncture because in the first exam, the contrast hardly reaches the brain and there is no risk of iatrogenic injury to the medulla oblongata. To minimize the neurotoxic effects, the ideal contrast should be radiopaque, water soluble, mis­cible with the cerebrospinal fluid (CSF), nontoxic and removed from the CSF by physiological processes. Iohexol contrast was used effectively, without neurotoxicity upon clinical evaluation while the volume used was sufficient to determine the injury site. The reported case demonstrated the possibility of performing lumbar myelography on Procyon cancrivorus effectively without significant complications or difficulties.Keywords: wildlife, neurology, myelographic examination, Procyon cancrivoru.

Surgical treatment of lumbar stenosis in achondroplasia

Object. The authors conducted a study to evaluate the results of a unique surgical procedure for treating primary lumbar stenosis in patients with achondroplasia, based on its distorted anatomical dimensions. Methods. A consecutive single-center series of 36 achondroplastic dwarfs with symptomatic lumbar stenosis underwent dynamic lumbar myelography to determine the most stenotic lumbar segment. This level was surgically decompressed by selective widening of the lumbar interapophyseolaminar diameter; laminectomy was not performed. The L2–3 level was decompressed in 97% of the cases and the L1–2 and L3–4 levels in 58 and 61%, respectively. Lower lumbar levels were rarely affected by stenosis. Stenosis typically did not occur at the level of the lamina, where the pseudoscalloping of the vertebral body compensates for the spinal narrowing, obviating the need for laminectomy. Complete relief of symptoms was demonstrated in 25 (71.4%) of 35 patients. Tolerable disease remained in eight patients (22.9%) postoperatively. In two cases (5.7%) surgery resulted in no benefit. One case was lost to follow up. The presence of a lumbar epidural hematoma complicated one procedure. Conclusions. In this series the interapophyseolaminar decompression was demonstrated to be an effective and safe procedure for the treatment of symptomatic stenosis in achondroplasia. The upper lumbar segments, particularly the L2–3 level, were most frequently involved. Dynamic lumbar myelography proved mandatory in demonstrating the symptomatic level.