A principal components analysis self-organizing map.

We propose a new self-organizing neural model that performs principal components analysis. It is also related to the adaptive subspace self-organizing map (ASSOM) network, but its training equations are simpler. Experimental results are reported, which show that the new model has better performance than the ASSOM network.     

Fluoroscopic percutaneous lumbar zygapophyseal joint cyst rupture: a clinical outcome study

Background contextLumbar zygapophyseal joint (Z-joint) synovial cysts can cause low back pain (LBP), spinal stenosis, and lower extremity radiculopathy. In the literature, there are several minimally invasive techniques described with mixed results. Typical recommended treatment is surgical resection of the cyst. Currently, there is little information available concerning the efficacy and outcome with treatment of Z-joint synovial cyst by percutaneous, fluoroscopic, contrast-enhanced distention, and rupture.PurposeTo evaluate the therapeutic value and safety of Z-joint cyst rupture in symptomatic patients.Study design/settingRetrospective cohort study in an academic outpatient physiatric spine practice.Patient sampleThirty-two patients with moderate-to-severe LBP and leg pain (18 women and 14 men with an age range of 46–86 y; mean age, 66 y) with an average preprocedure symptom duration of 5 months. The patient's clinical symptoms correlated with magnetic resonance imaging studies documenting the presence of a synovial cyst at the corresponding level and side of symptoms. Patients had at least 6 months follow-up (range, 6–24).Outcome measuresNumerical Pain Rating Scale, Roland-Morris Disability Questionnaire, North American Spine Society four-point patient satisfaction survey, recurrence of synovial cyst requiring repeat rupture, and need for surgical intervention.MethodsPatients with symptomatic lumbar Z-joint synovial cyst were identified and their charts were reviewed. Patients included in the study either had symptomatic lumbar LBP or LBP with associated lower extremity radiculopathy. All patients in the study had magnetic resonance imaging's documenting Z-joint synovial cyst that corresponded with the patients' clinical symptoms. All patients received fluoroscopically guided, contrast-enhanced, percutaneous facet cyst distention and rupture followed by an intra-articular facet joint injection of 1 cc kenalog and 1 cc of 1% lidocaine. Seventeen of the patients also received a transforaminal epidural steroid injection just before facet cyst rupture. Telephone follow-up was conducted on all patients.ResultsExcellent long-term (average follow-up 1 y; range, 6–24 mo) pain relief was achieved in 23 (72%) of 32 patients undergoing facet cyst rupture. Twelve patients (37.5%) had synovial cyst recurrence and 11 chose to undergo repeat rupture, which resulted in 5 patients (45%) obtaining complete relief of symptoms and 6 patients (55%) requiring surgical intervention for cyst removal. Fisher exact test demonstrated that all patients who did not have a cyst recurrence were a success and obtained complete relief of symptoms (p<.0002). Patients who underwent a repeat rupture had a 50% chance of a successful outcome. There was no statistical significance between a successful outcome and level of facet cyst rupture, the presence of spondylolisthesis, sex, age, or having a transforaminal epidural steroid injection at the time of the procedure. Wilcoxon signed-rank test demonstrated that the difference in Numerical Pain Rating Scale and Roland-Morris Disability Questionnaire scores before and after the procedure was statistically significant (p<.0001). No complications were reported.ConclusionsFluoroscopic percutaneous Z-joint cyst rupture appears to be a safe and effective minimally invasive treatment option. This procedure should be considered before surgical intervention.     

Results of gastrojejunal anastomotic technique designed to reduce stricture

BackgroundThe incidence of strictures developing after gastrojejunostomy has been reported to range from 3% to 31%. We found an unacceptably high stricture rate (13%) using a 21-mm circular stapler. Attempts to use the 25-mm circular stapler were frustrated by disparities between the size of the instrument and the patient's anatomy. We, therefore, modified the technique to accomplish the anastomosis with the linear stapler and hand sewing (LSA) at community hospitals in Southern California.MethodsA total of 124 anastomoses were accomplished with the circular stapler (CSA) followed by 100 anastomoses using the LSA technique. Drains were used routinely with the CSA technique but were used only selectively with the LSA technique. Stricture was defined as that requiring endoscopic dilation for symptoms. Leaks were confirmed radiologically or surgically, and bleeding was defined as the need for transfusion. Our analysis used the Student t test and Fisher's exact test, with P <.05 considered statistically significant.ResultsNo patient died. The LSA technique was faster and resulted in significantly fewer postoperative strictures and complications compared with the CSA technique.ConclusionThe results of our study have shown that the LSA technique, as described, is preferable to the CSA technique.