A novel beamformer-based imaging of phase-amplitude coupling (BIPAC) unveiling the inter-regional connectivity of emotional prosody processing in women with primary dysmenorrhea

Objective. Neural communication or the interactions of brain regions play a key role in the formation of functional neural networks. A type of neural communication can be measured in the form of phase-amplitude coupling (PAC), which is the coupling between the phase of low-frequency oscillations and the amplitude of high-frequency oscillations. This paper presents a beamformer-based imaging method, beamformer-based imaging of PAC (BIPAC), to quantify the strength of PAC between a seed region and other brain regions.Approach. A dipole is used to model the ensemble of neural activity within a group of nearby neurons and represents a mixture of multiple source components of cortical activity. From ensemble activity at each brain location, the source component with the strongest coupling to the seed activity is extracted, while unrelated components are suppressed to enhance the sensitivity of coupled-source estimation.Main results. In evaluations using simulation data sets, BIPAC proved advantageous with regard to estimation accuracy in source localization, orientation, and coupling strength. BIPAC was also applied to the analysis of magnetoencephalographic signals recorded from women with primary dysmenorrhea in an implicit emotional prosody experiment. In response to negative emotional prosody, auditory areas revealed strong PAC with the ventral auditory stream and occipitoparietal areas in the theta-gamma and alpha-gamma bands, which may respectively indicate the recruitment of auditory sensory memory and attention reorientation. Moreover, patients with more severe pain experience appeared to have stronger coupling between auditory areas and temporoparietal regions.Significance. Our findings indicate that the implicit processing of emotional prosody is altered by menstrual pain experience. The proposed BIPAC is feasible and applicable to imaging inter-regional connectivity based on cross-frequency coupling estimates. The experimental results also demonstrate that BIPAC is capable of revealing autonomous brain processing and neurodynamics, which are more subtle than active and attended task-driven processing.

The contribution of the medial calcaneal osteotomy to the correction of flatfoot deformities

HYPOTHESES/PURPOSE

The success of the medial displacement calcaneal osteotomy in correcting flatfoot deformities is likely to be the result of a shift of the Achilles tendon forces on the hindfoot. The purpose of this study was twofold: 1) to define the contribution of the Achilles tendon to the flatfoot deformity, and 2) to define the effect of a calcaneal medial displacement osteotomy.

METHODS

We used six different experimental dynamic stages: 1) intact foot without Achilles loading; 2) intact foot with Achilles loading; 3) flatfoot without medial calcaneal displacement osteotomy and without Achilles loading; 4) flatfoot without medial calcaneal displacement osteotomy but with Achilles loading; 5) flatfoot with medial calcaneal displacement osteotomy but without Achilles loading; and 6) flatfoot with medial calcaneal displacement osteotomy and with Achilles loading. The experimental flaffoot was developed by releasing the posterior tibial tendon, spring ligament, and plantar fascia and applying 7,000 cycles of axial fatigue load (range, 700 to 1,400 N; 1-Hz frequency). To simulate the phase of midstance, the peroneus longus, peroneus brevis, flexor digitorum longus, and flexor hallucis longus tendons were grasped by clamps, connected to pneumatic actuators, and loaded with precalculated forces. Anteroposterior and lateral radiographs were obtained for each stage on which the following measurements were made: talonavicular coverage angle, talar-first metatarsal angle, talocalcaneal angle, and height of the medial cuneiform. These measurements were compared with a one-way ANOVA.

RESULTS

Between stages 1 and 2, all measurements were statistically insignificant. Between stages 3 and 4, for all measurements, Achilles tendon loading aggravated the flatfoot deformity (p < 0.05). After medial calcaneal osteotomy (stages 5 and 6), the Achilles tendon contributed less to the arch-flattening. We found that the medial displacement osteotomy plays an important role in reducing and/or delaying the progress of flatfoot deformity.

CONCLUSIONS/SIGNIFICANCE

In the flatfoot, loading of the Achilles tendon increases the deformity. Medial calcaneal osteotomy significantly decreases the arch-flattening effect of this tendon and therefore limits the potential increase of the deformity.

Experimental flatfoot model: the contribution of dynamic loading

The goal of this study was to determine if the application of muscle forces (simulating the dynamic phase of the midstance part of gait) had an effect on flatfoot deformity. We created a flatfoot model in each of seven cadaver foot specimens by grasping the Achilles, peroneus longus, peroneus brevis, flexor digitorum longus, and flexor hallucis longus tendons with soft-tissue vice clamps connected via wire cables to pneumatic cylinders. The experiment included four stages: 1) initial static axial loading; 2) axial loading after 3,000 load cycles (average, 735 N; range, 70 to 1400 N); 3) axial loading after releasing the spring ligament and plantar fascia; and 4) axial loading after an additional 3,000 load cycles. At each stage, both static (with axial loading only) and dynamic (axial loading with tensioning of the tendons to simulate the muscle forces at midstance) conditions were evaluated radiographically. No change was observed between the static and dynamic conditions in the first two phases of the experiment. After the third phase, changes in the talar-first metatarsal angle and the height of the medial cuneiform were noted, particularly in the dynamic condition. These and additional radiographic changes were magnified in the fourth phase, but only in the dynamic condition. We concluded that, to create an effective flatfoot model, the medial structures, including the spring ligament and possibly the plantar fascia, must be severed. Cyclic loading of the foot further increased the arch flattening, and this effect was magnified by dynamic loading.

Six first metatarsal shaft osteotomies: mechanical and immobilization comparisons

Because malunion (usually with dorsal elevation of the first metatarsal) has been reported after the treatment of severe hallux valgus deformities by proximal osteotomies, the current study was designed to compare the sagittal stability of six different metatarsal shaft osteotomies: the proximal crescentic, proximal chevron, Mau, Scarf, Ludloff, and biplanar closing wedge osteotomies. A plate was used in the biplanar closing wedge osteotomy; all others used screws for fixation. Ten fresh-frozen, human anatomic lower extremity specimens were used for each osteotomy. Failure loads were measured as units of force (newtons) and converted to pressure (kilopascals). Then the F-Scan system, which uses a thin insole to measure plantar pressure, was used to evaluate the pressure under the first metatarsal of seven volunteers using four types of shoes. According to the results, in patients with normal bone stock who are compliant, any of the four shoe types tested may be used after a Ludloff, Scarf, biplanar wedge (plantar screw fixation), or Mau osteotomy, but the wedge-based shoe should be used after a proximal crescentic or chevron osteotomy or for patients with severe osteopenic bone.

Unruptured congenital aneurysm of the sinus of Valsalva presenting with pulmonary stenosis

Congenital aneurysm of the sinus of Valsalva is a rare cardiovascular anomaly. It is usually silent until rupture occurs. The natural history of unruptured aneurysm of the sinus of Valsalva is still not clear, and the therapeutic strategy is uncertain. Here we reported a case of unruptured aneurysm of the sinus of Valsalva which was correctly diagnosed before invasive diagnostic procedures. A 30-year-old female noted mild palpitation and dyspnea for 1 month. Physically, a grade 3/6 systolic ejection murmur at upper left sternal border was detected. Echocardiography revealed dilatation and irregular protrusion of the right sinus of Valsalva encroaching on right ventricular outflow tract to cause obstruction. With these findings, unruptured aneurysm of the sinus of Valsalva with pulmonary stenosis was diagnosed. Cardiac catheterization and angiography confirmed the diagnosis. The aneurysm was repaired with a Dacron patch with good results. It is concluded that sinus of Valsalva aneurysm can be diagnosed by echocardiography before its rupture so as to render a proper management for this potentially life-threatening anomaly.

Transcatheter closure of a huge pulmonary arteriovenous fistula with embolization coils

A 46-year-old female with bilateral pulmonary arteriovenous fistulas was treated with Gianturco coil occlusion. The small right lung fistula was closed with a 6 mm coil, whereas the huge left lung fistula was occluded with three coils (one 10-mm and two 8-mm). Angiography 3 d later demonstrated recanalization of the left fistula. Two 8 mm coils were inserted to achieve complete obstruction again. She developed pulmonary infarction in the left lung 2 d later, which recovered without sequelae. We conclude that coil embolization for huge pulmonary arteriovenous fistula is feasible but may result in pulmonary infarction.