Prevalencia y características morfométricas del foramen mastoideo y vena emisaria mastoidea en población mexicana / Prevalence and morphometric characteristics of mastoid foramen and mastoid emmisary vein in the Mexican population

Las descripciones anatómicas del foramen mastoideo (FM) y la vena emisaria mastoidea (VEM) son escasas en la literatura. Dicho conocimiento es fundamental para realizar un abordaje quirúrgico de la fosa craneal posterior o región mastoidea. El objetivo del estudio fue determinar la prevalencia, variantes y características morfométricas del FM y VEM en población mexicana. Se evaluaron 176 hemicráneos por dos observadores independientes cegados el uno del otro, se determinaron la prevalencia, número y características morfométricas. La prevalencia del FM entre los dos lados fue de 75% con una mayor frecuencia de forámenes del lado izquierdo comparado con el lado derecho; respecto al número de forámenes se encontraron 108 hemicráneos con un foramen único, 22 con doble foramen y 2 con triple foramen. La prevalencia del FM y VEM fue de 75%, siendo la variante única la más frecuente.

The anatomic descriptions of mastoid foramen (MF) and mastoid emissary vein (MEV) are lacking in the literature. This knowledge is fundamental for the surgeon who is about to perform surgery of the posterior fossa or mastoid region. This study aims to determine the prevalence of MF and MEV in Mexican population, determine the morphometric characteristics of MF and describe possible variations in the number, size, location and asymmetry. In this study 88 craniums were evaluated (176 hemicranium) by two independent observers who did not have access to information of each other´s results. The prevalence, number and the morphometric characteristics were determined. MF prevalence of the two sides of the skull was 75 % with a higher frequency of the left foramina compared to the right side; in reference to the number of foramina we found 108 hemicranium with a single MF, 22 double and 2 triple foramen. In conclusion, the prevalence of MF and MEV in this study is 75%, this single variant noted as being the most frequent.

Pulsatile Tinnitus Caused by a Dilated Mastoid Emissary Vein

Although pulsatile tinnitus can be audible, objective demonstration of this heartbeat-synchronous sound has rarely been successful. We report a rare case of pulsatile tinnitus in a 44-yr-old female patient, which was induced by a large mastoid emissary vein (MEV) and objectively documented by Doppler sonography of the left posterior auricular region. The tinnitus was intermittent and the patient could adapt to the tinnitus without intervention on the mastoid emissary vein. These findings suggest that a single large MEV can cause pulsatile tinnitus in the absence of other vascular abnormalities, and imaging studies of the posterior fossa and Doppler ultrasonography can aid the diagnosis in such cases.

Study of mastoid canals in dried human skulls

To search for vascular tunnels or canals in the mastoid region which may not been reported before in Egyptian population, and may be of surgical importance. The study was carried on 30 complete dried Egyptian skulls, and 20 hemisected skulls or separated temporal bones. Another 10 hemisected heads preserved in formalin, and injected with gelatin/lead oxide mixture were also used. These heads were used to detect structures traversed the mastoid canal if present. Examination of dried bones revealed the presence of canal or tunnel on the outer surface of the mastoid processes in 37.5% of studied specimens. These canals were anterior to the occipitomastoid suture by a distance ranged from 0.5 to 1.8 cm. The canals were anteroinferior to the asterion by a distance ranged from 1 to 2.3 cm. The length of the canal varied from 0.2 to 2 cm. The lower opening of the canal was anterior or anterosuperior to the mastoid foramen. Dissection of injected heads showed that the canals contained a branch of occipital artery. The mastoid canals are not peculiarly confined to Indian population but they also found in skulls of Egyptian population. The presence of these canals in some skulls may be due to ossification of squamotemporal bone over the vessels during development of the mastoid process. The mastoid canals traversed by the auricular branch of occipital artery, which lied anterior to the mastoid foramina. This branch could be injuried if unnoticed by the surgeon. It is necessary for surgeons operating in this area to be aware of this vascular arrangement to anticipate and avoid troublesome bleeding

Radiographic aspects and angioarchitectural arrangements in corrosion casts of the blood supply to the human sternocleidomastoid muscle by the sternocleidomastoid branch of the occipital artery

A contribuicao do ramo esternocleidomastoideo da arteria occipital para a irrigacao do musculo esternocleidomastoideo foi avaliada em cadaveres humanos nao fixados, atraves da injecao de contraste radiografico e de resina polimerizavel para estudo da microvasculatura. O musculo foi dividido nos tercos superior, medio e inferior, a partir da sua insercao no processo mastoideo do osso temporal. Na maioria dos musculos, o pediculo superior apresentou-se formado por dois ramos paralelos longitudinais. Em todos os casos, o contraste radiografico atingiu ou ultrapassou a parte media do musculo. Na parte mais distal do terco inferior, ha pouca ou nenhuma contribuicao do pediculo superior para a irrigacao dessa regiao muscular sugerindo...