How best to measure the levator hiatus: evidence for the non-Euclidean nature of the 'plane of minimal dimensions'.

OBJECTIVE: To clarify whether the 'plane of minimal dimensions' of the levator hiatus on three-dimensional (3D) ultrasound accurately represents the minimal anatomical transverse hiatal dimension during a Valsalva maneuver. METHODS: In this retrospective study of 3D transperineal ultrasound and magnetic resonance (MR) imaging, datasets from 19 female participants were used to measure the transverse diameter of the levator hiatus using the plane of minimal dimensions on maximum Valsalva maneuver. The term 'apparent minimal transverse diameter' (aMTD) was used to define the transverse diameter measured using axial ultrasound and comparable axial or coronal MR images. Coronal MR images, using the plane of the vagina as a reference, were also obtained on maximum Valsalva. The transverse diameter measured between the caudal margin of the pubococcygeus/puborectalis on the MR coronal image is denoted by the term 'true minimal transverse diameter' (tMTD). Statistical comparisons between the aMTD and tMTD were made using Student's t-test. RESULTS: No significant difference was demonstrated between the aMTD as measured by ultrasonography and MRI. However, there were significant differences found between the aMTD measured by both ultrasound and MRI and the tMTD measured on coronal MR images (both P < 0.01), with mean ( ± SD) values of 4.36 ± 0.85, 4.13 ± 1.09 and 3.23 ± 0.49 cm, respectively. CONCLUSION: This study highlights the complexity and 3D nature of the levator hiatus and pelvic floor muscles. Investigators have previously assumed that the plane of minimal dimensions of the hiatus can be measured in a flat plane, however, the 3D nature of the hiatus means that the true levator hiatus occupies a warped (non-Euclidean) plane. Hiatal measurements on Valsalva may be subject to systematic error if performed in a single section, i.e. using a flat (Euclidean) plane.

Pelvic floor function in nulliparous women using three-dimensional ultrasound and magnetic resonance imaging.

OBJECTIVE: To compare biometric measures of pelvic floor function obtained using three-dimensional (3D) ultrasound and magnetic resonance imaging (MRI) in a group of nulliparous asymptomatic young women. METHODS: Twenty-seven asymptomatic nulliparous volunteers were assessed prospectively, using translabial 3D ultrasound and multiplanar 3D MRI. Levator hiatal dimensions were measured in the axial plane in both modalities. All participants were imaged supine, after voiding with data acquired at rest, on maximum Valsalva and maximum pelvic floor contraction. Interobserver variability was determined for both methods. Normally distributed continuous ultrasound data were compared with equivalent MRI parameters, and intraclass correlation coefficients were used to estimate correlation between the two methods. Bland-Altman analysis was also used to estimate agreement between methods. RESULTS: Interobserver repeatability was fair to excellent for all parameters measured with both methods. Moderate-to-substantial agreement between methods was shown for all tested parameters (intraclass correlation coefficients 0.587-0.783). There was a systematic but nonsignificant difference between methods, in that measurements on Valsalva tended to be larger for MRI, and the poorest agreement (intraclass correlation coefficient 0.587) was found for hiatal area on Valsalva. CONCLUSION: Agreement between the two methods was moderate to substantial for all parameters except for hiatal area on Valsalva. Magnetic resonance imaging yielded higher area measurements on Valsalva, which may indicate difficulties in identifying the plane of minimal dimensions due to poorer temporal resolution compared with ultrasound imaging.

Intussusception of the small bowel discovered incidentally by computed tomography.

Three cases of asymptomatic intussusception in adults are reported, discovered incidentally during a CT scan of the abdomen. It is being increasingly observed in adults, possibly aided by the reformatting capabilities of the new multislice CT scanners. It has been documented in children where it is considered to be transient and of no clinical significance.

Organo-axial volvulus of the sigmoid colon.

A 59 year old man presented with subacute abdominal distension and diarrhea. Plain radiographs and barium enema demonstrated organo-axial volvulus of the sigmoid colon. The radiologic, surgical, and pathologic findings are presented. The radiologic differences between organo-axial volvulus and the common mesentero-axial volvulus of the sigmoid colon are discussed.

Petrosal sinus catheterization in sheep. Development of a method for sampling hormonal output from the pituitary.

A relatively nontraumatic method has been developed to catheterize the petrosal sinus (PS) of sheep, via the internal jugular vein (IJV), using a percutaneous approach monitored by fluoroscopy. Preselection of suitable animals was facilitated by injecting radiopaque material through a cannula inserted into the deep facial vein to display the venous drainage from the pituitary. Further injections, via the same cannula, were later used to assist in the maneuvering of the catheter/wire guide combination as it passed up the IJV. To confirm catheter placement, plasma samples, collected simultaneously from PS and external jugular vein (EJV), were analyzed for growth hormone (GH). GH concentrations were consistently higher in the PS samples than in those found in the EJV, and more GH pulses were seen in PS samples than in the general circulation.

Determinants of vertebral mineral density in patients receiving long-term glucocorticoid therapy.

This study addresses the impact of clinical and biochemical factors on the bone density of patients receiving glucocorticoid therapy. Vertebral mineral density was measured by quantitative computed tomography in 35 patients aged 17 to 77 years who had received therapeutic glucocorticoid drugs for 0.1 to 22 years. The mean (+/- SEM) vertebral mineral density z score in the subjects was -1.7 +/- 0.2. z score was unrelated to underlying diagnosis, sex, or age but was significantly related to the duration of previous steroid therapy (r = -.38) and to the total cumulative glucocorticoid dose (r = -.50). The rate of change of bone density in 16 of these subjects followed up over a period of 12 months was -8.9% and was significantly greater in subjects taking more than 12.5 mg of prednisone per day. Bone loss was not influenced by sex, age, duration of previous steroid treatment, or diagnosis and was not predictable from biochemical measures of calcium metabolism.

Fatal high cervical spinal cord injury in an automobile accident complicating os odontoideum.

We report a case where spinal instability from incomplete fusion of the dens of C2 (os odontoideum) allowed anterior displacement of the skull and first cervical vertebra following right frontal impact against the A pillar in an automobile accident. Resultant crushing and laceration of the spinal cord occurred at the level of C1 and C2. Without either radiographic investigation or detailed examination of the spine, the fatal injury might have been overlooked and death attributed to acute alcoholic poisoning because the blood alcohol level was .613%.

Ultrasonic investigation of the circumoral musculature.

Real-time ultrasound with a high frequency probe is used to image the circumoral musculature with the lips relaxed and contracted. The ultrasonic images show that muscle tissue makes up only a part of the total thickness of the lip, and varies among individuals in shape, transonicity (clearness) and thickness. The muscle layer in the upper lip is sandwiched between layers of facial and lingual connective tissue, while the muscle image in the lower lip lies close to the lingual surface. In a relaxed state the muscle layer in the lower lip is significantly thicker than that in the upper lip, and a mean difference also occurs in contraction, but to a considerably lesser degree. Thus the upper lip muscle appears to increase in thickness during contraction relatively more than does that of the lower lip. Furthermore, the contraction in the upper lip seems to occur fairly uniformly along the lip from left to right. The muscular changes in the lower lip are more complex, even though embryologically complexity is ascribed properly to the upper lip. In the lower lip contraction seems to occur in the lateral parts and in the mentalis muscle, but in the midline the orbicularis oris muscle remains quite inactive. More complex arrangements are essential merely to ensure support of the lower lip against gravity.

Bilateral hypoglossal nerve palsy due to vertical subluxation of the odontoid process in rheumatoid arthritis.

Two patients with rheumatoid arthritis involving the cervical spine developed a rapidly progressive dysarthria due to bilateral hypoglossal nerve palsies, in one patient as an isolated lesion, and in the other in conjunction with dysfunction of the vagus and glossopharyngeal nerves. Both patients showed upward movement of the axis, relative to the foramen magnum, which has been termed 'vertical subluxation of the odontoid' or 'cranial settling'. Mechanical injury to the nerves, secondary to this process, is the most likely mechanism.

Pre-operative balloon occlusion of the renal artery for radical nephrectomy.

Six of 8 patients with renal tumours were successfully catheterised pre-operatively and the renal artery occluded by a Swan Ganz balloon tipped arterial catheter. At subsequent radical nephrectomy early ligation of the renal vein was readily accomplished and there was noticeable decrease in vascularity and engorgement of the kidney and its tumour.