Atheromatosis of the brain-supplying arteries: Circle of Willis, basilar, vertebral and their branches.

PURPOSE: Atherosclerotic plaques in the brain-supplying arteries are slowly-developing alterations of vascular structures that can lead to neurological impairment due to stenosis and insufficient oxygenation of eloquent brain areas. The aim of this study is to provide detailed demographic information related to the incidence of atherosclerotic plaques in the cerebral arteries. MATERIAL AND METHODS: Forty-eight circles of Willis (21 men, 21 women, mean age: 70.26, six samples unknown) were macroscopically analyzed for length, diameter, and presence of atherosclerotic plaques. Statistical analysis was used to identify potential differences in the locations and frequencies of atherosclerotic plaques in relation to age and sex. RESULTS: The study sample revealed 261 atherosclerotic plaques. The key findings were significant correlations between plaque development and age and between plaque location and age; however, there was no significant sex difference. CONCLUSION: The upper and lower branches of the middle cerebral artery (MCA) were novel locations predisposing to plaque development. A cut-off value at 60 years revealed a significant difference in plaque development and distribution. There were no significant sex differences in the occurrence of atherosclerotic plaques.

The carotid axis revisited.

The aim was to determine the variations in the level of origin of carotid bifurcation and diameters of the common, internal, and external carotid arteries which is clinically important for several interventional procedures. Therefore, 165 human embalmed corpses were dissected. The data collected were analyzed using the Chi square-test and the Pearson correlation test. The results of previous studies have been reviewed. In relation to the level of the carotid bifurcation, taking as a reference point the hyoid bone, the values ranged from 4 cm below the hyoid body to 2.5 cm above the body of the hyoid, being the average height-0.33 cm, with a standard deviation of 1.19 cm. The right carotid bifurcation was established at a higher level (x = - 0.19 cm.) than the left one (x = - 0.48 cm.) (p = 0.046). On the contrary, no significant gender differences could be observed. The arterial calibres of the common and internal carotid arteries were higher in male than female. In the internal carotid artery (X = 0.76 cm.), the left was greater than the right (X = 0.72 cm.) (P = 0.047). However, no differences in the distribution of the calibre of the external carotid artery were found neither by side nor gender. Variations in the level of bifurcation and calibres of carotid arteries are relevant for interventional radiology procedures and head and neck surgeries. Knowledge of these anatomical references might help clinicians in the interpretation of the carotid system.

[Central projections of the rat recurrent laryngeal nerve]. / Proyecciones centrales del nervio laríngeo recurrente de la rata.

Laryngeal nerves contain the fibres that control the laryngeal function. The studies carried out on the rat with the purpose of having a better knowledge of the functional components and the real origin of the fibres conveyed by the recurrent laryngeal nerve (RLN) are few and in disagreement. No one of such papers were developed using biotinylated dextrane amines (BDA), a powerful tool for tracing neural pathways. The aim of our study was to identify in the rat using BDA, the nuclei of real origin of the fibres of the RLN, knowing in this way the functional components of this nerve. The study has been developed in 31 adult male Sprague-Dawley rats, applying the BDA into the lesioned RLN. The results obtained in all the animals show that the rat's RLN does not contain afferent fibres, whereas the efferent fibres were originated within the ipsilateral nucleus ambiguus (NA). So, in the rat, the RLN seems to contain exclusively efferent fibres, probably been the superior laryngeal nerve who conveyed the afferent fibres.

[Central projections of the rat superior laryngeal nerve]. / Proyecciones centrales del nervio laríngeo superior de la rata.

Laryngeal nerves contain the fibres that control the laryngeal function. On the rat, the studies on the functional components and the real origin of the fibres conveyed by the superior laryngeal nerve (SLN) are few. No one of such works were developed using biotinylated dextrane amines (BDA), a powerful tool for tracing neural pathways. The aim of our study was to identify by using BDA, in the rat, the nuclei of real origin of the fibres of the SLN, knowing in this way the functional components of this nerve. The study has been developed in 11 adult male Sprague-Dawley rats, applying the BDA into the damaged SLN. The results obtained in all the animals shown that the rat SLN carries efferent fibres originated within the ipsilateral nucleus ambiguous (NA) and dorsal nucleus of the vagus (DNV), and that afferent fibres reach the tractus solitari and the nucleus tractus solitari. So, in the rat, the SLN seems to convey efferent fibres from the NA and DNV and, probably, all the laryngeal afferent fibres.

[Morphometry of the recurrent laryngeal nerves of the rat]. / Morfometría de los nervios laríngeos recurrentes de la rata.

In mammals the recurrent laryngeal nerves are dissimilar in length between both sides. This asymmetry involves different time of arrival of the stimulus to the laryngeal musculature controlled by each nerve. Thus, several explanations have been addressed to elucidate the closest of the glottis at the same time despite the unlike length of the nerves. However, previous works on the topic lack of several important data. The present study compares, in two groups of 10 and 6 rats, the length and the composition of myelinated fibers in the recurrent laryngeal nerves of both sides, by means of light microscopy and a computerized morphometric analysis. The results show a mean difference of 0,84 cm longer the left than the right recurrent laryngeal nerve. No statistical differences were observed in the number of myelinated fibers between both sides. However, the myelinated fibers of the right side were statistically bigger in diameter than the fibers of the left side. The data are discussed in the context of the mechanisms for the compensation of the dissimilar length of both recurrent laryngeal nerves.

An anatomical study of anastomoses between the laryngeal nerves.

OBJECTIVE: To systematize the anatomy of the connecting branches between laryngeal nerves. METHODS: Microdissection of 90 larynges obtained from necropsies (57 men and 33 women; age range, 41-95 y). RESULTS: Anastomoses between the internal and recurrent nerves appeared in four different patterns: 1) Galen's anastomosis, as the connection between the dorsal branches of both nerves (100%); 2) arytenoid plexus, as the connection between the arytenoid branches of both nerves, in relation with the arytenoid muscle, and divided in a deep part (100%) and a superficial part (86%); 3) cricoid anastomosis, previously only described in cows, located in the front of the cricoid lamina (6/10 cases); and 4) thyroarytenoid anastomosis, as the connection of a descending branch of the internal laryngeal nerve and an ascending branch of the recurrent nerve (14%). Anastomosis between the internal laryngeal and the external laryngeal nerves appeared as a connecting branch throughout the foramen thyroideum (21%). Anastomosis between the external laryngeal and recurrent nerves appeared as a connecting branch throughout the cricothyroid muscle (68%). CONCLUSION: At least two anastomoses (Galen's anastomosis and arytenoid plexus) appeared in 21% of hemilarynges, and 79% of cases had three or more anastomoses between the laryngeal nerves. The different prevalence of this complex anastomotic pattern suggests functional differences in the sensory and motor innervation of individual subjects.

Foramen thyroideum: a comparative study in embryos, fetuses, and adults.

The incidence and characteristics of foramen thyroideum (FT) in embryonic and/or fetal larynges have not been established. In the present study, 90 adult larynges and 53 embryonic-fetal larynges were studied. The incidence of FT during the embryonic-fetal period (57%) was statistically different from the adult period (31%) (P = 0.005). All the FT found in the adult period contained vessels and/or nerves, while in the embryonic and fetal period only 63% presented neurovascular elements (P < 0.001). The origin of FT in the embryonic period and its persistence during adult life is discussed.

[Glottic immobility: retrospective study of 229 cases]. / Inmovilidad glótica: estudio retrospectivo de 229 casos.

A retrospective study of the unilateral and bilateral vocal fold immobility cases diagnosed at our hospital between 1985 and 1998 was carried out. Of the 229 cases studied, vocal fold immobility was bilateral in 58 patients (25%), unilateral right in 60 (26%), and unilateral left 111 (49%). The most frequent etiologies in the bilateral cases were thyroid surgery (38%) and prolonged intubation (31%); idiopathic cases (32%) and thyroid surgery (23%) in the unilateral right cases; and idiopathic cases (28%) and extralaryngeal tumors (22%) in the unilateral left cases. Clinical compensation was achieved in more than 85% of cases of unilateral immobility when the etiology was idiopathic or due to surgical damage to the recurrent or vagus nerves, 70% when it was a prolonged intubation, 56% in neurological patients and 38% in extralaryngeal tumors. In patients with bilateral vocal fold immobility, 14% did not require any treatment, 34% had a permanent tracheostomy, and 52% recovered adequate naso-oral ventilation after surgery (tracheostomy only in 12 patients and arytenoidectomy in 18 patients).

Proposal of landmarks for clamping neurovascular elements during endoscopic surgery of the supraglottic region.

BACKGROUND: Bleeding within the supraglottic region can be a lethal complication after CO(2) laser microsurgery. Our aim was to propose endoluminal anatomical landmarks to locate the superior laryngeal vessels resulting in a safer microsurgery. METHODS: Endoluminal dissections were made in 22 larynges without laryngeal disease. RESULTS: The neurovascular structures were in the superior third of a triangle defined by the vocal process, the anterior commissure, and the epiglottic attachment of the aryepiglottic fold. They overlapped in 4 different ways: pattern I (70.4%): superior laryngeal vein (SLV), superior laryngeal artery (SLA), and internal laryngeal nerve (ILN); pattern II (13.6%): SLA, SLV, ILN; pattern III (4.6%): SLV, ILN, and SLA; pattern IV (4.6%): SLA, ILN, and SLV. CONCLUSION: Microsurgery in the supraglottic region may be safer if surgeons are aware of the superior third of the above-defined triangle, "danger area", where the vascular elements of this region are located.

Femoral nerve entrapment: a new insight.

Compression of the femoral nerve in the iliac fossa has been reported as a consequence of several pathologies, but never as a result of muscular compression. Aberrant slips of iliacus, however, have occasionally been reported to cover or split the femoral nerve. This study aimed to assess such variations as potential factors in femoral nerve compression. A large and homogeneous sample of 121 embalmed cadavers (242 specimens) was studied. Statistical comparisons were made using the chi-squared test. Muscular slips from iliacus and psoas, piercing or covering the femoral nerve, were found in 19 specimens (7.9%). No significant differences by sex or side were found. The more frequent variation was piercing of the femoral nerve by a muscular slip (17 specimens, 7.0%). The nerve then entered the thigh as one or more branches. The less frequent variation found was a muscular slip or sheet covering the femoral nerve as it lay on iliacus (2 specimens, 0.8%). Each disposition may be a potential risk for nerve entrapment.

Patterns of the circumflex femoral arteries revisited.

Knowledge of variations of the circumflex femoral arteries is important when undertaking clinical procedures within the femoral region and in hip joint replacement. Since the 19th century, many different patterns have been proposed to classify their origins. This work studied a statistically reliable sample, the lower limbs of 221 embalmed human cadavers (equal right-left and approximately equal sex distributions), and reviewed the previous literature to propose a unified and simple classification that will be useful to clinicians. Statistical comparisons were made using the chi(2) test. The medial and lateral circumflex femoral arteries have been classified into three different patterns based on the levels of their origin. Distribution related to sex and side was also studied. Pattern I: Both arteries arose from the deep femoral artery (346 cases, 78.8%). This pattern was more frequent in females, P = 0.01. There was no significant difference between sides. Type Ia, medial circumflex femoral artery origin was proximal to the lateral circumflex femoral artery origin (53.2%); Type Ib, lateral circumflex femoral artery origin was proximal to medial circumflex femoral artery origin (23.4%); Type Ic, both arteries arose from a common trunk (23.4%). Pattern II: One of the arteries arose from the femoral artery and the other from the deep femoral artery (90 cases, 20.5%). Type IIa, the medial circumflex femoral artery arose from the femoral artery (77.8%) and Type IIb, the lateral circumflex femoral artery arose from the femoral artery (22.2%). There were no significant differences between sexes or sides. Pattern III: Both arteries arose from the femoral artery (2 cases, 0.5%). In every disposition there was a significantly higher prevalence of unilateral rather than bilateral occurrence. In one dissection the medial circumflex femoral artery was absent. Awareness of these variations could avoid unexpected injuries.