Influence of cervical spine stabilization via Stiff Neck on the postural system in healthy patients: compensation or decompensation of the postural system?

Functional and structural disorders of the cervical spine are often regarded as the cause of non-specific vertigo. Pathogenetically, disorders of proprioceptive connections between neck muscles and vestibular cores as well as the proprioceptors in the cervical facette joints are presumed. According to a study by Hülse and Hölzl (HNO 48:295-301, 1), after manual therapeutic intervention in patients with functional disorders of the cervical spine 50% of the probands stated a significant reduction of their vertigo. This was backed up in posturography, which documented an improvement in vestibulospinal reactions. To date, the effects of artificial as well as surgical stabilization of the cervical spine on the balance system have not been explored yet. In a first pilot study, we examined the influence of artificial stabilization of the cervical spine via cervical collar Stiff Neck, manufactured by Ambu/Perfit ACE] on the balance system of 20 healthy probands. For this purpose, a posturography (Balance Master Systems, NeuroCom, Clackamas, OR, USA) was applied to 20 healthy probands (10 males, 10 females) with a mean age of 35 years who had no prior spine pathology. Posturography was analyzed under static and dynamic test situations with and without Stiff Neck cervical collar. The results were compared statistically to the Wilcoxon test. In the static test situation of the modified clinical test of sensory interaction on balance, a significantly improved standing stability occurred. In none of the dynamic tests did fixation of the cervical spine by Stiff Neck cuff lead to a measurable impairment of the movement coordination. All probands felt subjectively more stable when wearing the Stiff Neck. In healthy probands, a fixation of the cervical spine leads to a stabilization of the postural balance situation. This fixation seems to be helpful in compensating the malfunction of other components of balance information. In a next step, this same model of analysis is applied to patients with cervical instability. Standing stability and movement coordination before and after cervical fusion are being explored.

[Epithelialization model of non-biological tissue replacement materials in vitro]. / Epithelisierungsmodell nicht-biologischer Gewebeersatzmaterialien in vitro.

Successful use of non-biologic implants in reconstructive head and neck surgery is dependent on tissue compatibility and epithelization. This is true not only for epithelial cells, but also for mesenchymatic cells. Therefore we tested several substrates with human fibroblasts or keratinocytes from the oral mucosa in cell culture. In tissue culture keratinocyte outgrowth from small mucosal flaps onto the surface was observed. Preparations were evaluated by histology and scanning electron microscopy. Cellulose-ester, polyvinylidene-difluoride and polyglactin developed monolayers of fibroblasts and keratinocytes in cell cultures. In tissue culture mucosal flaps showed good adherence to the surface of these materials and a fine outgrowth of keratinocytes. Expanded polytetrafluor-ethylene (ePTFE) was partially covered by a layer of fibroblasts and keratinocytes in cell culture, but cell adherence was not sufficient. In tissue culture the mucosal flaps failed to attach on ePTFE. These results illustrate that the mesenchymatic and epithelial component of cell and tissue cultures show different qualities of cellular adherence and growth on the surface of non-biologic implants. We propose our method for the development of an in-vitro model for the epithelization of non-biologic implantation materials.

[Effect of monaural deprivation on maturation of the auditory pathway in the Mongolian gerbil (Meriones unguiculatus)]. / Einfluss monauraler Deprivation auf die Reifung der Hörbahn bei der mongolischen Wüstenrennmaus (Meriones unguiculatus).

Several investigations prove that monaural acoustic deprivation induces detrimental changes in the auditory pathway. So far the major interest focused on degenerative processes on the deprived side, while effects on the contralateral untreated side were not taken into consideration. This ontogenetic study investigates effects of early monaural acoustic deprivation on the functional development of the acoustically evoked auditory brainstem response (ABR) in the Mongolian gerbil. Young gerbils were deafened by a single intracochlear application of neomycin sulfate. The ABR development on the contralateral side differed in a late developmental period from that of normally hearing animals. These changes persisted until adulthood. Between day 55 and day 90 a significant 5 dB decrease of the ABR thresholds and a significant shortening of the interpeak latency II-V occurred. The results confirm that a complete monaural deprivation during the sensible or critical period leads on the contralateral side to plastic or compensatory changes in the auditory brainstem.

A method for the induction of a cochlea-specific auditory deprivation in the gerbil (Meriones unguiculatus).

The neurophysiological effects of early electrical stimulation on the development and neural plasticity of the central auditory system in prelingually deafened children with cochlear implants are still unknown. Many of these basic questions can be answered systematically only in animal experiments. Meriones unguiculatus is a well-established animal model in hearing research. Deafening is produced by a single intracochlear application of an ototoxic aminoglycoside antibiotic (neomycin sulfate) on the 14th day after birth (DAB), i.e. before the late natural onset of hearing on the 16th DAB. A single application of the antibiotic abolishes auditory brainstem responses (ABR) to clicks completely and reduces sensitivity to low frequency tonebursts by 50 dB SPL. Scanning electron microscopy results show a destruction of the stereocilia of the inner and outer hair cells of the basal and medial cochlear turn and a reduction of those in the apical turn. Our method avoids a systemic application of antibiotics and can be used in studies dealing with the consequences of different forms of auditory deprivation, neuronal compensation processes or with ontogenetic studies and chronic electrostimulation in an animal model.

[A registration system for evaluating acusto-mechanical transmission of middle ear implants]. / Ein Messsystem zur Uberprüfung des akustomechanischen Ubertragungsverhaltens von Mittelohrimplantaten.

A measurement system was developed that permits objective comparisons of the sound conduction of middle ear implants. The implants are fitted into a mechanical middle ear model which approximates the impedances of the eardrum and the inner ear. A defined signal within the frequency range of 0-5 kHz is provided by a miniaturized loudspeaker at the input to the model and is measured by a probe microphone. Displacement of an artificial stapes footplate at the output of the model is measured by a fiberoptic probe with a sensitivity of 5 nm. The transmission function is calculated as the quotient of the output and the input signal. This system can be used to evaluate the sound-transmitting properties of different middle ear implants excepting other influences, such as surgical techniques. This work details the measurement system and demonstrates basic influences on the sound-transmission of middle ear implants.