A wearable system for pre-impact fall detection.

Unique features of body segment kinematics in falls and activities of daily living (ADL) are applied to make automatic detection of a fall in its descending phase, prior to impact, possible. Fall-related injuries can thus be prevented or reduced by deploying fall impact reduction systems, such as an inflatable airbag for hip protection, before the impact. In this application, the authors propose the following hypothesis: "Thigh segments normally do not exceed a certain threshold angle to the side and forward directions in ADL, whereas this abnormal behavior occurs during a fall activity". Torso and thigh wearable inertial sensors (3D accelerometer and 2D gyroscope) are used and the whole system is based on a body area network (BAN) for the comfort of the wearer during a long term application. The hypothesis was validated in an experiment with 21 young healthy volunteers performing both normal ADL and fall activities. Results show that falls could be detected with an average lead-time of 700 ms before the impact occurs, with no false alarms (100% specificity), a sensitivity of 95.2%. This is the longest lead-time achieved so far in pre-impact fall detection.

Recent advances in the treatment of sensorineural deafness.

In the developed world, there are currently more than 100 million people afflicted with hearing loss. In the United States and European Community alone, there are an estimated 21 million people with significant conductive hearing loss, whilst there are over 90 million suffering from moderate to severe sensorineural hearing loss. Of these, more than 65 million hearing-impaired persons are without treatment. This article presents a review of the latest technological advances and treatment options for the hearing-impaired, including external and middle ear devices, bone-anchored hearing aids, cochlear implants and hybrids, auditory brainstem implants. Finally, we take a glimpse into the future prospects of stem cell treatment and hair cell regeneration with gene delivery to the inner ear for the treatment of sensorineural hearing loss.

The application of three-dimensional magnetic resonance imaging rendering of the inner ear in assessment for cochlear implantation.

OBJECTIVE: To study the use of three-dimensional (3D) rendering of T2-weighted magnetic resonance imaging (MRI) images into 3D models of the inner ear in the preoperative assessment for cochlear implantation. STUDY DESIGN: A retrospective case review of cochlear implant candidates undergoing preoperative imaging studies to determine their suitability for surgical implantation. SETTING: A tertiary referral center for the northwest area of England with an established 10-year-old program in cochlear implantation. PATIENTS: Selected adult and pediatric patients referred for cochlear implant assessment from 1996 to 1998, who underwent computerized tomography (CT) and MRI studies. INTERVENTION: Diagnostic imaging modality to assess the structure and patency of the inner ear. MAIN OUTCOME MEASURES: To see how detailed anatomic information provided by these 3D models influenced surgical decisions. RESULTS: Four case studies (with their 3D models) are presented to illustrate different points of interest. CONCLUSION: These 3D models provide the implanting surgeon with precise, detailed, and easily interpretable information about the cochlea, which help to guide surgical implantation, or in certain cases, to decide against attempting surgery in the presence of unfavorable anatomic factors.

Tinnitus as the presenting symptom in a case of Lhermitte-Duclos disease.

Dysplastic gangliocytoma or Lhermitte-Duclos disease (LDD) is a hamartomatous malformation of the cerebellar hemisphere that usually presents with signs of increased intracranial pressure or symptoms of cerebellar dysfunction. In this paper, we report a case of LDD presenting with tinnitus, and postulate a probable mechanism for this unusual presentation.

Medial efferent inhibition suppresses basilar membrane responses to near characteristic frequency tones of moderate to high intensities.

Efferent inhibition of low and medium spontaneous-rate fiber activity in response to characteristic frequency (CF) tones is greater at levels between 50 and 75 dB SPL than at lower levels, and even occurs at levels of 100 dB SPL [Guinan and Stankovic, J. Acoust. Soc. Am. 100, 1680-1690 (1996)]. The self-mixing effect of a laser diode was used to measure tone-evoked, basilar membrane (BM) displacements in the basal turn of the guinea pig cochlea during electrical stimulation of the medial efferent system. Efferent stimulation suppresses BM displacement and, for frequencies close to the CF of the measurement site and above, attenuation of tone-evoked displacements appears to be greatest for levels between 50 and 75 dB SPL, and efferent attenuation could exceed 10 dB SPL for tones at 90 dB SPL. By comparison, the attenuation of the BM vibrations caused by tones at frequencies below CF was found to be greatest for low sound pressure levels. The findings of Guinan and Stankovic therefore have their origin in events present in the vibrations of the BM.

The effect of efferent stimulation on basilar membrane displacement in the basal turn of the guinea pig cochlea.

Tone-evoked basilar membrane (BM) displacements were measured with a laser diode interferometer from the basal turn of the guinea pig cochlea. The olivocochlear bundle (OCB) was electrically stimulated for 60--80 msec periods at rates of < 200 sec-1 via electrodes placed at the point at which the OCB crosses the floor of the fourth ventricle. For tones close to the best or characteristic frequency (CF), OCB stimulation tended to linearize the highly compressive displacement-level functions and to displace the steep, low-level region toward higher intensities along the intensity axis by < 27 dB sound pressure levels. This shift resulted in a desensitization of the tip of the BM displacement tuning curve that was associated sometimes with downward shifts in the tuning curve CF of < 500 Hz. OCB-induced suppression of the BM response was not associated with a consistent broadening of the tuning curve or with major changes in the phase of the BM response. At frequencies in the low-frequency tail of the tuning curve, OCB stimulation had no observable effect on the motion of the BM. The effect of OCB stimulation on the BM response was blocked by perfusing the scala tympani with 1 microM strychnine. Thus, the effect of OCB stimulation on the frequency tuning of the BM is very similar to the effect of OCB stimulation on the sensitivity and frequency tuning of afferent fibers and inner hair cells. The results indicate that the postsynaptic action of the OCB may cause a change in gain of the voltage-dependent outer hair cell motility without observable changes in the stiffness of the cochlear partition or the position of the BM.

Airway compression by vascular anomalies in infants and neonates.

Despite the tremendous health-care advances in recent years, external compression of the tracheobronchial tree by cardiovascular anomalies still remains a significant cause of morbidity and potential mortality in neonates and infants. As the initial presenting symptoms can be deceivingly mild, the diagnosis is easily missed without a high index of suspicion by the investigating clinician utilising the appropriate investigations. Four case studies are presented, (i) illustrating the importance of tracheobronchoscopy in assessing any neonate or infant with suspected airway obstruction; (ii) reviewing the current literature, and (iii) suggesting a comprehensive diagnostic approach by way of relevant investigations.