Hiperplasia coronoidea bilateral. Una rara patología causante de disfunción temporomandibular / Bilateral coronoid hyperplasia. An uncommon pathology cause of temporomandibular disorders

La hiperplasia coronoidea es una condición patológica muy poco frecuente, caracterizada por un crecimiento exagerado de la apófisis coronoides mandibular unilateral o bilateral. Desde la primera descripción realizada por Langenbeck a mediados del siglo XIX han aparecido descritos ocasionalmente en la literatura nuevos casos de esta rara alteración. Aunque en ocasiones es asintomática, su principal manifestación clínica es la restricción de la movilidad mandibular, principalmente en los movimientos de apertura y protrusión. Dicha limitación se debe a la impactación de la apófisis coronoides con el hueso cigomático. En este trabajo se presenta el caso clínico de un varón de 30 años de edad sin antecedentes médicos de interés que acude a consulta por un cuadro de limitación de apertura progresiva y dolor en la región temporomandibular. Tras la exploración, el empleo de técnicas radiológicas convencionales y especiales permitieron confirmar el diagnóstico de hiperplasia coronoidea bilateral. Así mismo, en este trabajo se recogen los principales aspectos clínico patológicos y diagnósticos de esta alteración. Se realiza un repaso de los aspectos más importantes en el diagnóstico diferencial de los procesos que cursan con limitación de la apertura bucal. Dentro de este diagnóstico diferencial, y a pesar de su baja prevalencia, debe incluirse esta patología (AU)

Coronoid hyperplasia is an uncommon pathology characterized by an excessive uni or bilateral growth of the mandibular coronoid process. Since the first description by Langenbeck in the middle of the XIX century, many cases have been reported in the literature. In some cases patients are asymptomatic. Nevertheless, in most of them a limitation in the mouth movements can be observed, especially during the opening and protrusion movements. This limitation is caused by the impact of the coronoid process with the zigomatic bone. In this paper we present the case of a 30 years old male patient, without other medical history, that was remitted to our service because of the presence of severe pain in the temporomandibular area and a progressive limitation of the mouth opening. After the clinical exploration a radiographic exam was carried out. Based on them the patient was diagnosed of bilateral coronoid hyperplasia. We also review the most important aspects on this disease, especially those related to the differential diagnosis with other pathologies causing limitation of mouth movements. Coronoid hyperplasia must be always considered in the differential diagnosis in cases of progressive mouth movement limitation, although this is a really uncommon pathology (AU)

Chronic variable stress induces supersensitivity of central alpha2-adrenoceptors which modulate the jaw-opening reflex in the rat.

In a previous study, we found that the sensitivity of central postsynaptic alpha2-adrenoceptors which modulate, in an inhibitory way, the activity of the jaw-opening reflex (JOR) is reduced after chronic repeated stress (tail pinch) in the rat. The aim of this study was to assess the effects of exposure to a chronic variable stress regime on these adrenoceptors. To do this, the digastric electromyographic responses elicited by orofacial electrical stimulation after the intravenous administration of cumulative doses (x3.3) of the alpha2-adrenoceptor agonist, clonidine (0.1-10000 microgram/kg), were recorded. As expected, in unmanipulated control rats, clonidine inhibited the reflex, in a dose-dependent manner, until abolition (ED50 = 17.3 +/- 2.2 microgram/kg). Single tail pinch did not significantly alter the ability of clonidine to abolish the reflex. However, chronic variable stress led to an enhancement of the inhibitory effect of clonidine on the amplitude of JOR, resulting in a shift to the left of the dose-response curve in comparison with that of the control group (ED50 was reduced by 37%, P = 0.032), without affecting either the estimated maximum effect for the agonist or the slope of the inhibitory function. This in vivo result indicates that chronic variable stress leads to an increased sensitivity of central alpha2-adrenoceptors which modulate JOR, in contrast to the desensitization of these adrenoceptors found after repeated exposure to the same stressor.

Gamma-aminobutyric acid-immunoreactive neurons in the rat trigeminal nuclei.

The distribution of GABAergic neurons in the rat trigeminal nuclei was studied using a highly specific monoclonal antibody (mAb3A12) to gamma-aminobutyric acid (GABA). Immunopositive cells were relatively abundant in the marginal and gelatinosa beds of the caudal part of the trigeminal spinal tract nucleus, and in the dorsomedial areas of the oral subnucleus and the principal nucleus. A high density of GABA-immunoreactive somata was also found in the rostral part of the oral subnucleus and in the adjacent parvicellular reticular formation as well as in the supratrigeminal and intertrigeminal regions. Thus, the distribution of the GABAergic cells showed a relatively high density in areas related to the convergence of sensory stimuli, and in zones that contain interneurons inhibiting masticatory motoneurons. The results suggest, therefore, that GABA might play an important role both in discriminative sensory processing and in reflex modulation of the orofacial region.