Bernardo De-Ary-Pires

The human digastric muscle: Patterns and variations with clinical and surgical correlations

The digastric muscle is located in the suprahyoid region on each side and frequently exhibits two muscular bellies (anterior and posterior) linked by an intermediate tendon. The paired digastric muscles act together either depressing the mandible or elevating the hyoid bone; therefore acting as a single muscle with important physiological roles. In the present study, the digastric muscle has been analyzed bilaterally in 74 adult human cadavers. A computerized morphometrical investigation of the digastric muscles has been performed (Image Pro Plus software package, Media Cybernetics, USA) and the resulting quantitative data have been statistically assessed (SPSS 11.0 for Windows, USA). We hereby propose an original morphological classification that encompasses five types (I-V) for the anterior belly (AB); three types (I-III) for the intermediate tendon (IT); and two types (I-II) for the posterior belly (PB) of the human digastric muscle. In each digastric muscle, the aforementioned anatomical types have been characterized according to the muscular bellies and intermediate tendon. Consequently, as a result of the combinations of those diverse types, individual digastric muscles have been considered as pertaining to distinctive morphological patterns (named from A to J). Cases with absence of either AB or PB have been included in patterns K and L and would be more appropriately defined as monogastric muscles. This innovative classification provides clear-cut anatomical parameters for interpreting morphological variants of the digastric muscle with relevant clinical and surgical correlations.

Axonal and extracellular matrix responses to experimental chronic nerve entrapment

We have analyzed the ultrastructural and histopathological changes that occur during experimental chronic nerve entrapment, as well as the immunohistochemical expression of chondroitin sulfate proteoglycan (CSPG). Adult hamsters (n = 30) were anesthetized and received a cuff around the right sciatic nerve. Animals survived for varying times (5 to 15 weeks) being thereafter perfused transcardially with fixative solutions either for immunohistochemical or electron microscopic procedures. Experimental nerves were dissected based upon the site of compression (proximal, entrapment and distal). CSPG overexpression was detected in the compressed nerve segment and associated with an increase in perineurial and endoneurial cells. Ultrastructural changes and data from semithin sections were analyzed both in control and compressed nerves. We have observed endoneurial edema, perineurial and endoneurial thickening, and whorled cell-sparse pathological structures (Renaut bodies) in the compressed nerves. Morphometrical analyses of myelinated axons at the compression sites revealed: (a) a reduction both in axon sectional area (up to 30%) and in myelin sectional area (up to 80%); (b) an increase in number of small axons (up to 60%) comparatively to the control group. Distal segment of compressed nerves presented: (a) a reduction in axon sectional area (up to 60%) and in myelin sectional area (up to 90%); (b) a decrease in axon number (up to 40%) comparatively to the control data. In conclusion, we have shown that nerve entrapment is associated with a local intraneural increase in CSPG expression, segmental demyelination, perineurial and endoneurial fibrosis, and other histopathological findings.

Myofibroblast persistence and collagen type I accumulation in the human stenotic trachea

Postintubation tracheal stenosis (PITS) is associated with an increased use of assisted ventilation in intensive care units. We investigated both collagen type I accumulation and myofibroblast localization in human PITS lesions excised for surgical therapeutic procedures, compared with normal tracheas.

The developmental anatomy of the human superior hypogastric plexus: A morphometrical investigation with clinical and surgical correlations

The superior hypogastric plexus (SHP) is the part of the autonomic nervous system, which is responsible for the sympathetic innervation of pelvic organs and extrapelvic genitals in humans of both sexes. The SHP also functions as the anatomic pathway for the major part of visceral sensitive fibers originating from pelvic viscera. In this study, the morphology of the SHP was analyzed through anatomical dissections performed both in human adult and fetal cadavers. A computerized morphometrical investigation of the SHP was also performed and the resulting quantitative data statistically assessed. The comparison between fetal and adult SHP revealed that in the male group there was a developmental increase of six times (in height) and of about five times (in width); while in the female group, there was a developmental increase of 3.5 times both in height and width values. In addition, the distance from the superior border of the SHP to the bifurcation of the common iliac arteries presented a developmental increase of about six times in the male group, and about four times in the female group. We propose an original morphological classification with six types, based upon the anatomical arrangement of the nervous fibers in this autonomic plexus. Clin. Anat. 23:962–970, 2010.

Experimental chronic entrapment of the sciatic nerve in adult hamsters: an ultrastructural and morphometric study

Entrapment neuropathy is a group of clinical disorders involving compression of a peripheral nerve and interference with nerve function mostly through traction injury. We have investigated the chronic compression of peripheral nerves as an experimental procedure for detecting changes in ultrastructural nerve morphology. Adult hamsters (Mesocricetus auratus, N = 30) were anesthetized with a 25% pentobarbital solution and received a cuff around the right sciatic nerve. Left sciatic nerves were not operated (control group). Animals survived for varying times (up to 15 weeks), after which they were sacrificed and both sciatic nerves were immediately fixed with a paraformaldehyde solution. Experimental nerves were divided into segments based upon their distance from the site of compression (proximal, entrapment and distal). Semithin and ultrathin sections were obtained and examined by light and electron microscopy. Ultrastructural changes were qualitatively described and data from semithin sections were morphometrically analyzed both in control and in compressed nerves. We observed endoneurial edema along with both perineurial and endoneurial thickening and also the existence of whorled cell-sparse structures (Renaut bodies) in the subperineurial space of compressed sciatic nerves. Morphometric analyses of myelinated axons at the compression sites displayed a remarkable increase in the number of small axons (up to 60%) in comparison with the control axonal number. The distal segment of compressed nerves presented a distinct decrease in axon number (up to 40%) comparatively to the control group. The present experimental model of nerve entrapment in adult hamsters was shown to promote consistent histopathologic alterations analogous to those found in chronic compressive neuropathies.

Strapping the spinal cord: an innovative experimental model of CNS injury in rats.

Experimental models of spinal cord (SC) lesion are essential for understanding a few of the primary and secondary mechanisms of injury and functional recovery of the central nervous system (CNS). We have developed an experimental model of SC injury in adult rats (n=32), that involves the use of a device (SC-STRAPPER) that straps the SC and promotes gradual and controlled SC injury similar to clinical compressive SC injuries. SC strapping is a less-invasive procedure in comparison to other SC injury models, and it performs compression with smaller infection risk and undetectable paravertebral or vertebral lesions. The survival of the rats was 100%, minimizing the suffering of the animals. We have analyzed the histopathological changes that occur during experimental SC compression, as well as the immunohistochemical labeling for glial fibrillary acidic protein (GFAP). Animals survived for 21 days being thereafter anesthetized and perfused with aldehydes. SC lesions were associated with motor deficits and local increase in GFAP immunolabeling proportionate to the severity of the compression. This experimental model represents a potential contribution for neuroscientific research, providing a low-cost and rather simple system of controllable and reproducible SC experimental damage.

The human superior tarsal muscle (Müller's muscle): a morphological classification with surgical correlations

The superior tarsal muscle (STM) is a smooth muscle that originates from the undersurface of the levator palpebrae superioris muscle (LPSM) and inserts onto the superior tarsal plate (STP) of the upper eyelid. We have performed a morphometrical investigation of the STM in 49 adult human cadavers (34 males, 15 females). Histological analysis has shown a transitional area between the skeletal striated muscle (LPSM) and the adjacent smooth muscle (STM). We propose an original morphological classification based upon the attachment of STM to the upper border of the STP. Accordingly, we describe four patterns of STM. Pattern 1 (P1) consists of STM attachment to the central portion of the STP. Pattern 2 consists of both medial (P2M) STM attachment to both the central and medial regions of the STP and lateral (P2L) STM attachment to both the central and lateral regions of the STP. Pattern 3 (P3) consists of STM attachment along the whole extent of the STP. Pattern 3 was the most frequently observed pattern (63.27%) followed by patterns P2M (24.49%), P2L (8.16%) and P1 (4.08%). P3 was the predominant pattern in males (73.52%), while in females, both patterns P2M (46.66%) and P3 (40.00%) were equally prevalent. The analysis of paired specimens revealed a symmetrical arrangement in 72.20% of all cases, with the remaining cases (27.80%) displaying left–right STM asymmetries. To the best of our knowledge, this is the first description of the STM asymmetries in the medical literature. This innovative classification provides anatomical parameters for interpreting morphological variations of the STM with relevant applications in both plastic surgery and ophthalmology.