Ultrasound Examination and Localization of the Sciatic Nerve: A Volunteer Study

Background: Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation.

Methods: In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded.

Results: The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion.     

Oxybutynin versus propantheline in patients with multiple sclerosis and detrusor hyperreflexia

Hyperreflexia is the most common urological finding in patients with multiple sclerosis. A prospective randomized study was done to compare the effectiveness of 2 commonly used drugs, oxybutynin and propantheline. Of the 34 patients entered into the trial 19 were treated with oxybutynin and 15 with propantheline. The urological symptoms (frequency, nocturia, hesitancy, urgency and urge incontinence) were graded according to severity from 0 to 3. Patients with urinary infection were excluded. Urodynamic examination, consisting of cystometrography and electromyography, was performed in all patients before treatment. Both groups of patients had comparable neurological, urological and urodynamic status before treatment. In 4 patients (21 per cent) treated with oxybutynin and in 4 (27 per cent) treated with propantheline side effects were so severe that the treatment had to be discontinued. Symptomatic response to oxybutynin was good in 10 patients (67 per cent), fair in 2 (13 per cent) and poor in 3 (20 per cent). Propantheline produced good symptomatic results in 4 patients (36 per cent), fair in 1 (9 per cent) and poor in 6 (55 per cent). The mean increase in maximum cystometric capacity on cystometrography was significantly larger in the oxybutynin group than in the propantheline group (144 +/- 115 versus 35 +/- 101). Our results indicate that oxybutynin is more effective than propantheline in the treatment of detrusor hyperreflexia in patients with multiple sclerosis.     

Fusariotoxicoses of farm animals and mycotoxic leucoencephalomalacia of the equine associated with the finding of trichothecenes in feedstuffs

Mycotoxicoses involving horses, rabbits and cattle have been studied. Fusarium tricinctum and T-2 toxin were isolated from all incriminated feedstuffs. Other isolated trichothecenes from the feed included HT-2, verrucarins and roridin. The toxins were separated, identified and quantitated using thin-layer chromatography, gas-liquid chromatography and mass spectrometry. T-2 toxin was detected in amounts varying from 0.5-204 ppm. The contaminated feedstuffs in connection with the affected horses and rabbits, included cereal grains (corn, cornstalks, bran and barley), whereas fescue hay was associated with the mucocutaneous findings in the bovine episode. The effects of the toxin(s) seemed to be host specific and varied according to the different animal species. Horses and rabbits developed primarily central nervous disorders with conspicuous pathological findings in the brain. Hepatitis and nephritis were also seen in naturally intoxicated horses and experimentally fed rats. Affected cattle developed mucocutaneous eruptions around the mouth and nostrils. In addition, dermonecrotic findings were observed involving the extremities, ear and tail. Fusariotoxicoses are toxic conditions of farm animals and man caused by the ingestion of cereal grains and forages contaminated by different fungal species of the genus Fusarium. A variety of clinical and pathological findings have been reported (5,6,10,13,15,17,31). This study concerns neuropathic findings in horses and rabbits and mucocutaneous lesions in cattle in association with T-2 toxin contamination.     

Urethral function after chronic cauda equina lesions in cats. I. The contribution of mechanical factors and sympathetic innervation to proximal sphincter dysfunction

We investigated the contribution of mechanical and sympathetic neural factors to proximal urethral sphincter dysfunction in the cat after chronic sacral rhizotomy. Concomitant vesicostomy prevented a decrease in the urethral pressure profile measured three months post-rhizotomy. Sympathetic influences on basal urethral perfusion pressure were the same in neurally-intact and chronic rhizotomised cats. A significant prazosin-sensitive component of basal urethral perfusion pressure remained after section of all extrinsic urethral innervation in both neurally-intact and chronic cats. Local intra-arterial 6-hydroxydopamine also abolished this component. After rhizotomy, noradrenaline content in the proximal urethra was significantly increased but there was no change in sensitivity to sympathetic stimulation. A small (5% of control) atropine-sensitive and prazosin-resistant constriction was seen only after chronic sacral rhizotomy. We conclude that a mechanical factor associated with bladder expression and not an alteration in sympathetic control is the major factor leading to diminished proximal urethral closure after vesicourethral lower motor neuron lesion. Furthermore, short adrenergic neurons have an important role in the maintenance of urethral pressure in the normal state and after lower motor neuron lesion.