Peroneal neuropathy after weight loss: a high-resolution ultrasonographic characterization of the common peroneal nerve.

OBJECTIVE: The objective of this study was to use in vivo ultrasonographic imaging to analyze the common peroneal nerve in controls and patients who were diagnosed with peroneal neuropathy (PN) due to significant weight loss. We also looked for a relationship between weight loss (magnitude) and the occurrence of PN. MATERIALS AND METHODS: Fifty controls and six patients who were diagnosed with PN after losing a significant amount of weight were examined by means of ultrasonography (US). On the US images, the structure and reflectivity of the nerve were analyzed. Correlations were made between the ultrasonographic measurements and the body mass index (BMI) of controls. In PN patients, these ultrasonographic parameters were compared between the normal and pathological legs. RESULTS: BMI was positively correlated with the transverse cross-sectional area of the nerve and fibular tunnel in controls. In controls with a high BMI, the peroneal nerve appeared thicker and the US reflectivity of the nerve was higher. A lower US reflectivity was observed in the pathological legs of the six patients who developed PN after weight loss. CONCLUSION: The transverse cross-sectional area and reflectivity of the peroneal nerve on the US images could be viable tools in the diagnosis of PN after weight loss.

Foot drop as a complication of weight loss after bariatric surgery: is it preventable?

BACKGROUND: Although rare, the relationship between peroneal nerve palsy and weight loss has been well documented over the last decades. Of the 160 patients operated for persisting foot drop in our institution, weight loss was considered to be the major contributing factor for 78 patients (43.5%). METHODS: We compared patients who developed a foot drop after bariatric surgery with a control group of patients who underwent bariatric surgery (gastric banding) but did not develop peroneal neuropathy. RESULTS: 9 patients developed foot drop after bariatric surgery. The mean weight loss for these patients was 45 kg. Weight reduction took place during a mean period of 8.6 months. Our control group consists of 10 patients. The mean weight loss of these patients was 43.8 kg, and the weight reduction took place during a mean period of 21.7 months. CONCLUSION: In contrast to earlier studies, we demonstrated that significant weight loss is correlated with a higher risk to develop foot drop and that the time period in which the weight loss is achieved is important. A rapid reduction of body weight is correlated with a higher risk to develop foot drop.

The microanatomical environment of the subthalamic nucleus. Technical note.

High-frequency stimulation of the subthalamic nucleus (STN) is a widely performed method to treat advanced Parkinson disease. Due to the limitations of current imaging techniques, the 3D microanatomy of the STN and its surrounding structures in the mesencephalon are not well known. Using images they obtained using a 9.4-tesla magnetic resonance (MR) imaging unit, the authors developed a 3D reconstruction of the STN and its immediate surroundings. During the postmortem investigation of a human brain, a sample of tissue in the area around the STN was isolated. This brain tissue was scanned in the three orthogonal planes at 1-mm slice thickness. The images generated were compared with photographs of conventionally stained brain tissue slices in different neuroanatomical books, and a 3D reconstruction was made. High-field MR imaging is an appropriate method for visualizing the microanatomy of the STN and its surroundings. The images allow an optimal analysis of the microenvironment of the STN in the three orthogonal planes and can be used for 3D reconstructions of this area with possible clinical applications in the future.

Anatomical variability in the trajectory of the inside-out transobturator vaginal tape technique (TVT-O).

An experimental surgical study on human cadavers was undertaken to assess variability in the trajectory followed by the needle during application of the inside-out transobturator tape suspension (TVT-O) technique. The TVT-O surgical procedures were performed on six fresh female cadavers according to the standard recommended operative protocol. Subsequent anatomical dissection revealed that the needle had perforated the obturator membrane at a distance of 0.7 to 2.0 cm from the needle to the obturator canal. It subsequently followed a variable course passing at 0.5 to 2.0 cm from the anterior branch of the obturator nerve and 0.1 to 1.4 cm from the posterior branch. We conclude from this anatomical study that the TVT-O trajectory is subject to wider variability than was originally postulated.

Translevator posterior intravaginal slingplasty: anatomical landmarks and safety margins.

The posterior intravaginal sling is a new tension-free needle suspension technique. It is used for the treatment of middle compartment (vaginal vault or uterine) prolapse. The Prolene sling suspends the vagina at the upper border of level II support as described by DeLancey (Am J Obstet Gynecol 166:1717, 1992). Human cadaveric dissections were undertaken to explore the pertinent anatomy that is involved when using this blind needle technique. Pre-dissected cadaveric material was used to obtain didactic illustrations of the anatomy of the procedure. Description of the surgical technique using anatomical landmarks and relative distances of the needle to these landmarks will improve the surgeon's visual understanding of the procedure. The measurements obtained demonstrate that the needle stays at a minimal distance of 4 cm away from the major (pudendal) vessels that could potentially cause life-threatening haemorrhage.

Accessory intraventricular prominence of the occipital horn of the lateral ventricle.

OBJECT: Knowledge of normal variations in ventricular morphological features is important in endoscopic neurosurgery. Classically, two elevations are described on the medial wall of the occipital horn of the lateral ventricle: an upper bulb and a lower calcar avis. Nevertheless, a third, as yet unreported elevation may be present at the junction of the medial wall and the floor of the occipital horn. The authors report the frequency with which this third elevation was found in a series of cadaveric brains. METHODS: The medial wall of the occipital horn of the lateral ventricle was studied in the three orthogonal planes in 45 formalin-fixed cadaveric hemispheres. The underlying structures responsible for the observed intraventricular prominences were exposed by microdissection. A third elevation was present, lying ventrorostral to the calcar avis, in seven (47%) of the 15 single hemispheres, and bilaterally in six (40%) of the 15 whole brains. After microdissection, a fiber bundle from the splenium of the corpus callosum was seen emerging in the occipital horn at the angle between the tail of the hippocampus and the bulb of the occipital horn. The most rostral fibers fanned out inferolaterally along the floor of the collateral trigone. The larger, posterior part protruded into the medial wall along the ventral border of the calcar avis as far as the tip of the occipital horn. CONCLUSIONS: Besides its importance as a variation of normal ventricular morphological features, the close relationship of this accessory intraventricular prominence to the tail of the hippocampus should be kept in mind when intervening neurosurgically so that damage to the underlying commissural fibers can be avoided.

In vitro high-field magnetic resonance imaging-documented anatomy of a fetal myelomeningocele at 20 weeks' gestation. A contribution to the rationale of intrauterine surgical repair of spina bifida.

OBJECT: It remains uncertain if closure of a myelomeningocele at midgestation changes the neurological condition at birth in an infant born with spina bifida. The authors conducted a study to provide a detailed analysis of the morphology of the spinal cord with the myelomeningocele at the time fetal surgery usually is performed. METHODS: The myelomeningocele of a 20-week-gestation-age fetus was examined, and data were compared with those obtained in a neurologically intact specimen of the same age. In vitro high-field 9.4-tesla magnetic resonance (MR) microscopy was used to examine the fetal material. High-field MR spectroscopy provided images in the three orthogonal planes with a resolution comparable with low-power optical microscopy. The authors observed that the fetal cord of the myelomeningocele specimen was tapered and tethered at S3-4 while the conus medullaris in the normal fetus reaches L-4. No neurulation defects were noted. The axial MR images clearly revealed the nonfusion of the mesodermal structures. The absence of neurulation defects suggests that at least in some cases of spina bifida the spinal cord initially is well developed but is damaged later on chemically and mechanically. This might be an argument in favor of intrauterine myelomeningocele repair. By 20 weeks' gestation, however, the deformation of the cord inside the myelomeningocele is severe. An optimization of the preoperative assessment by means of MR imaging therefore might be considered a valuable contribution to intrauterine surgery. The in vitro high-field MR microscopic findings of this study could be used as references for clinical intrauterine MR imaging. CONCLUSIONS: The detailed in vitro high-field MR analysis of a 20-week-gestation-age fetus with spina bifida demonstrated that an improvement of the preoperative intrauterine imaging should be pursued to detect those cases without neurulation defects and with minimal deformation of the spinal cord.