Motor cortical representation of position and velocity during reaching

This study examines motor cortical representation of hand position and its relationship to the representation of hand velocity during reaching movements. In all, 978 motor cortical neurons were recorded from the proximal arm area of rostral motor cortex. The results demonstrate that position and velocity are simultaneously encoded by single motor cortical neurons in an additive fashion and that the relative weights of the position and velocity signals change dynamically during reaching. The two variables--hand position and hand velocity--are highly correlated in the standard center-out reaching task. A new reaching task (standard reaching) is introduced to minimize these correlations. Likewise, a new decoding method (indirect OLE) was developed to analyze the data by simultaneously decoding both three-dimensional (3D) hand position and 3D hand velocity from correlated neural activity. This method shows that, on average, the reconstructed velocity led the actual hand velocity by 122 ms, whereas the reconstructed position signal led the actual hand position by 81 ms.     

Acute dislocations of the distal radioulnar joint and distal ulna fractures

This article reviews acute dislocations of the distal radioulnar joint (DRUJ) and distal ulna fractures. Acute dislocations can occur in isolation or in association with a fracture to the distal radius, radial metadiaphysis (Galeazzi fracture), or radial head (Essex-Lopresti injury). Distal ulna fractures may occur in isolation or in combination with a distal radius fracture. Both injury patterns are associated with high energy. Outcomes are predicated on anatomic reduction and restoration of the stability of the DRUJ.     

Sexual function following surgery for urodynamic stress incontinence

The objective of this study was to compare sexual function in women before and after surgery for urodynamic stress incontinence in the absence of pelvic organ prolapse. This was a prospective questionnaire survey. Fifty-four women undergoing surgery (tension-free vaginal tape/tension-free vaginal tape-obturator) for urodynamic stress incontinence with no evidence of detrusor overactivity or concomitant prolapse were assessed preoperatively and 6 months post operatively. Assessment was based on the Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire (PISQ), the International Consultation on Incontinence Questionnaire (ICIQ) and the Patient Global Impression of Improvement. Paired t-tests were used for comparing pre- and post-op scores and unpaired t-tests for comparing observations between groups. Spearman’s rank correlation was used for testing whether two numerically scored items were related, and McNemar test was used to compare pre- and postoperative responses to individual questions. ICIQ scores showed significant improvement after surgery (p < 0.001). Women completing PISQ were significantly younger (mean = 54) than those who did not (mean = 65; p < 0.001). The total PISQ score was better postoperatively (preoperative = 87.2, postoperative = 92.7; p < 0.001), with improvements in both the physical (preoperative = 31.0, postoperative = 35.2; p < 0.001) and partner-related domains (preoperative = 18.8, postoperative = 19.9; p = 0.002) but no improvement in behaviour emotive domains (preoperative = 37.3, postoperative = 37.6; p = 0.70). There was a reduction in episodes of coital incontinence postoperatively (preoperatively = 16/54, postoperatively = 39/54; p < 0.002). Previous vaginal surgery, oestrogen status of respondents and hysterectomy status did not affect the PISQ. Surgical correction of stress incontinence is associated with an improvement in sexual function.     

Pubovaginal or Vicryl Mesh Rectus Fascia Sling in Intrinsic Sphincter Deficiency

The aim of this study was to compare the pubovaginal sling with a new Vicryl mesh rectus fascia (VMRF) sling in the surgical treatment of low urethral pressure genuine stress incontinence. Fifty-one consecutive women who had a VMRF (n= 27) or a pubovaginal sling (n= 24) procedure between March 1995 and December 1997 were evaluated. The patient-determined subjective success rate of the VMRF sling (85%) was significantly higher than that of the pubovaginal sling (58%) in women with low urethral pressure stress incontinence (P=0.03). The objective success rates following the VMRF and the pubovaginal sling were 52% and 50%, respectively. The prevalence of postoperative symptomatic voiding dysfunction and de novo detrusor instability was 7% after the VMRF sling and 25% following the pubovaginal sling (P=0.08). The VMRF sling had a higher patient-determined success rate and a lower complication rate than the pubovaginal sling, and should be considered in the surgical management of women with low urethral pressure stress incontinence.     

Stoma-related complications are more frequent after transverse colostomy than loop ileostomy: a prospective randomized clinical trial

BACKGROUND: The consequences of leakage from low colorectal or coloanal anastomoses are reduced by the use of a loop stoma to divert the faecal stream. Controversy continues as to whether loop ileostomy (LI) or loop transverse colostomy (LTC) is the optimal method of defunctioning such anastomoses. METHODS: Patients requiring defunctioning following anterior resection and total mesorectal excision were randomized to receive either LI or LTC. Comparison was made between the groups regarding the difficulty of stoma formation and closure, the recovery after stoma closure and stoma-related complications. The minimum follow-up after stoma closure was 6 months (median 36 months). RESULTS: Between October 1995 and August 1999, 70 patients were randomized (LTC 36, LI 34) of whom 63 underwent stoma closure (LTC 31, LI 32). There were no significant differences in the difficulty of formation or closure, or in the postoperative recovery between the groups. However, there were ten complications related directly to the stoma in the LTC group: faecal fistula (one patient), prolapse (two), parastomal hernia (two) and incisional hernia during follow-up (five). None of these complications occurred in the LI group. CONCLUSION: In this randomized study, the frequency of herniation before or after colostomy closure supports the choice of LI as a method of defunctioning a low anastomosis. Both methods appear to provide satisfactory protection for the low anastomosis.     

Reversal of focal misery perfusion after intracranial angioplasty: case report

OBJECTIVE AND IMPORTANCE: The presence of reduced blood flow and increased oxygen extraction fraction (OEF) (misery perfusion) in the hemisphere distal to an occluded carotid artery is a proven risk factor for subsequent stroke. Whether angioplasty of intracranial stenosis is sufficient to reverse this condition has not been documented. CLINICAL PRESENTATION: A 67-year-old man exhibited progressive right hemispheric ischemic symptoms despite maximal antiplatelet and antithrombotic therapy. Angiography demonstrated focal 80% stenosis of the supraclinoid segment of the ipsilateral internal carotid artery. TECHNIQUE: 15O positron emission tomographic measurements of cerebral blood flow and OEF were made before and after transfemoral percutaneous angioplasty. OEF values measured before angioplasty were elevated in the middle cerebral artery distal to the stenosis. Angioplasty reduced the degree of luminal stenosis to 40% (linear diameter). OEF values measured 36 hours after angioplasty were normal. CONCLUSION: Angioplasty of intracranial stenosis can restore normal cerebral blood flow and oxygen extraction, despite mild residual stenosis after the procedure. Hemodynamic measurements may be useful for the identification of patients with the greatest potential to benefit from angioplasty.     

Childhood fractures requiring inpatient management

INTRODUCTION: Fractures account for significant morbidity during childhood. Children requiring inpatient management for their fractures represent the most serious injuries. The aim of this study was to identify injury patterns in childhood fractures requiring inpatient management at a regional trauma centre. METHODS: Three thousand and forty two consecutive injured children were admitted to our orthopaedic centre over a 4-year period. Data was prospectively collected by independent audit clerks and entered onto a database. Data recorded included type of injury, mechanism of injury and place of injury. This was then used to assess injury patterns and trends. RESULTS: Upper limb and lower limb fractures accounted for 51% (n=1,565) and 21% (n=637) of all emergency admissions, respectively. Other causes included soft tissue injury, Infections, Polytrauma and Dislocations. Twice as many males were admitted with upper or lower limb fractures compared to females (67% versus 33%) (P<0.001). Males were more likely to be older (P<0.001) compared to females. Distal radial fractures accounted for 60% of upper limb fractures. Distal and midshaft tibial fractures accounted for 52% of lower limb fractures. Sports injuries were responsible for the majority of lower limb fractures with falls accounting for the majority of upper limb fractures. Fracture incidence peaked during summer months. CONCLUSION: Males are twice as likely to require inpatient management for fractures as females. Male adolescents are particularly at risk. Distal radial fractures following falls and distal tibial fractures following sports injuries are the most common fractures requiring admission. Identifying ways of minimising risk of these injuries would reduce childhood morbidity.     

Side-to-side nerve bridges reduce muscle atrophy after peripheral nerve injury in a rodent model

Background

Peripheral nerve injury can result in muscle atrophy and long-term disability. We hypothesize that creating a side-to-side bridge to link an injured nerve with a healthy nerve will reduce muscle atrophy and improve muscle function.

Methods

Sprague-Dawley rats were divided into four groups (n = 7 per group). Group 1: transection only—a 10-mm gap was created in the proximal tibial nerve; group 2: transected plus repaired—the transected tibial nerve was repaired; group 3: transected plus repaired plus nerve bridge—transected nerve repaired with a distal nerve bridge between the tibial and peroneal nerves via epineurial windows; and group 4: transected plus nerve bridge—transected tibial nerve left unrepaired and distal bridge added. Gait was assessed every 2 wk. At 90 d the following measures were determined: gastrocnemius mass, muscle and nerve nuclear density, and axonal infiltration into the nerve bridge.

Results

Groups 3 and 4 had greater improvements in walking track recovery than groups 1 and 2. Group 3's gastrocnemius muscles exhibited the least amount of atrophy. Groups 1, 2, and 4 exhibited greater histologic appearance of muscle breakdown compared with group 3 and control muscle. Finally, most bridges in groups 3 and 4 had neuronal sprouting via the epineurial windows.

Conclusions

Our study demonstrated reduced muscle atrophy with a side-to-side nerve bridge in the setting of peripheral nerve injury. These results support the application of novel side-to-side bridges in combination with traditional end-to-end neurorrhaphy to preserve muscle viability after peripheral nerve injuries.