[Functional recovery in hemifacial transplants in rats]. / Recuperación funcional del trasplante hemifacial en ratas.

INTRODUCTION: There are a number of different options open to the surgeon for the reconstruction of the face and scalp, but when tissue loss is very extensive, good aesthetic and functional recovery is not possible. Not only must the damaged tissues be replaced, but motor and sensorial functioning also has to be restored. AIM: To evaluate the functional recovery of hemifacial allografts in rats. MATERIALS AND METHODS: Twenty-one hemifacial flaps were transplanted from Long-Evans rats to Wistar-Lewis rats, under immunosuppression monotherapy with tacrolimus. Prior to the operation, anatomical and allograft viability studies were conducted. Two groups of transplanted rats were formed: with or without nerve repair. In the nerve repair group, end-to-end suture was employed to repair the infraorbital branch of the trigeminal nerve and the buccolabial, upper mandibular marginal and zygomatico-orbital branches of the facial nerve. Sensory recovery was evaluated by filming traction of the whiskers, whereas motor recovery was assessed by blind tests using electromyography studies of the mystacial muscles and electroneurography of the facial nerve. At eight weeks, the animals were sacrificed and biopsy samples were taken from the mystacial region. RESULTS: The facial flap was successfully lifted in 10 cases. In the nerve repair group both clinical and electrophysiological recovery were observed at six weeks, whereas biopsy samples taken in the eighth week showed recovery of the nerve fascicles. CONCLUSIONS: The hemifacial flap can be transplanted. By repairing the nerves of the allograft, it is possible to achieve its functional recovery, as can be confirmed clinically, electrophysiologically and histopathologically. To date, this is the first evidence of functional recovery following a hemifacial transplant in rats.

[The vestibulocollic reflex: assessment and characteristics of vestibular-evoked myogenic potentials analysed by age groups]. / Reflejo vestibulocervical. Valoracion y caracteristicas de los potenciales vestibulares miogenicos evocados analizados por tramos de edad.

INTRODUCTION: Obtaining vestibular-evoked myogenic potentials (VEMP) by means of the vestibulocollic reflex is a readily available technique that provides an image of vestibular functioning and is useful for evaluating the pathologies that involve compromise of the anatomical pathway of the reflex. Although normal patterns do exist, responses vary at different ages. AIM: To obtain reference values of the vestibulocollic reflex according to different age groups. SUBJECTS AND METHODS: We studied 40 volunteers with no symptoms of auditory or vestibular compromise. Each ear was stimulated separately by a series of clicks (sounds lasting 0.1 s; 3 pps; intensities of 100 dB nHL and 85 dB nHL) and recordings were made in the sternocleidomastoid muscles by means of surface electrodes as patients who were lying on their backs contracted these muscles as they lifted their heads. We studied the latency of the initial p13-n23 positive-negative potential and the peak-to-peak amplitude. The existence of later n34-p44 potentials was evaluated. RESULTS: No statistically significant differences were found between genders or between the two ears. We did not find any differences between the latencies of the waves according to the intensity of the stimulus, but there is a relationship between the amplitude of the p13-n23 potential and the intensity of the stimulus. The latencies of the responses in children under 10 years of age differ from those of the other groups, but no differences were found among those over the age of 11. CONCLUSIONS: The VEMP display steady and easily identifiable latencies. We obtained different reference values for latency in children under the age of 10 and those over 11 years old. The amplitude decreases with the intensity of the stimulus.

[Vestibular evoked myogenic potential: a contribution to the vestibular physiology and pathology knowledge. Quantitative patterns in healthy subjects]. / Potencial vestibular miogénico evocado: un aporte al conocimiento de la fisiología y patología vestibular. Patrones cuantitativos en la población normal.

INTRODUCTION: Vestibulocollic reflex is a muscular reflex which is activated by acoustic stimulation. It shows two components: the first one, the vestibular evoked myogenic potential (VMEP) related to the vestibular pathway and the second, to the auditive pathway. The VMEP potential could be useful for vestibular physiology and pathology knowledge. OBJECTIVE: To determine the VMEP's parameters of normality and to evaluate influential factors such as age, sex or stimulation intensity. MATERIAL AND METHODS: Prospective study of the VCR in 40 healthy individuals, distributed in 4 groups according to their age. Stimulation was carried out at 100db and 85db on each ear independently. RESULTS: There are not differences between both ears and sexes. Normal latency levels must be separated between two groups of age: older and younger than 11 years old. Normal absolute values of amplitude response differ depending on muscular contraction, age and stimulation intensity. It is more representative to consider the difference between the values obtained in the two ears of the same individual than to consider the absolute values.