Biomedical subjects

N N Ge

Publications and source records attributed to N N Ge.

3 recordsLinked to original sources

PubMed1998

Action potential latency shift by rarefaction and condensation clicks in Menière's disease.

Transtympanic electrocochleography using rarefaction and condensation clicks was performed on 122 ears of 112 patients, including 98 ears of 89 patients with Menière's disease (MD) and 24 ears of 23 patients without Menière's disease (NMD). The mean action potential (AP) latency difference between rarefaction and condensation clicks was 0.40 +/- 0.37 msec in the MD group and 0.06 +/- 0.07 msec in the NMD group (p < .01). An AP latency shift > 0.2 msec was found more often in the MD group (62.2% vs 8.3%) and in ears with an enlarged summating potential and AP ratio (69.7% vs 36.4%). The results suggest that comparison of rarefaction and condensation latencies may serve as a useful addition to electrocochleography in the diagnosis of MD.

Acoustic Stimulation↗

PubMed1998

Summating potential and action potential ratio in Meniere's disease before and after treatment.

OBJECTIVE: This study aimed to compare the summating potential and action potential ratio (SP:AP) in patients with Meniere's disease before and after various surgical and medical treatments as an indication of change in endolymphatic hydrops to study the progression of Meniere's disease. STUDY DESIGN: The study design was a retrospective case review. SETTING: The study was conducted at an otology-neurotology referral center. PATIENTS: Eighty-eight ears of 84 patients with Meniere's disease received medical treatment in 18 ears and surgical treatments including endolymphatic shunt in 12 ears, streptomycin perfusion of the lateral semicircular canal in 9 ears, streptomycin perfusion of the middle ear in 33 ears, and dexamethasone perfusion of the middle ear in 16 ears. INTERVENTION: Transtympanic electrocochleography (ECoG) was performed in all patients before treatment and 1-57 months after treatment (mean, 13.5 months) with a 2-year interval in 28 patients. MAIN OUTCOME MEASURE: An enlarged SP:AP ratio (> or = 0.40) was used as the diagnostic criterion for endolymphatic hydrops. RESULTS: Overall, an enlarged SP:AP ratio was found in 75% of ears before treatment and 78% after treatment. The SP:AP ratio, when enlarged, remained enlarged in 91% of ears. A nonenlarged SP:AP ratio before treatment became enlarged after treatment in 41% of ears. In American Academy of Otolaryngology-Head and Neck Surgery stage 1 Meniere's disease (pure-tone threshold average < or = 25 dB), an enlarged SP:AP was found in 58% of ears before treatment and 79% after. Twenty-five (89%) of 28 patients followed for 2 years were free of vestibular symptoms after treatment, and in 22 patients (79%), the SP:AP remained enlarged. The distribution of an enlarged SP:AP ratio was associated with the duration of disease (chi-square = 33.5552, p < 0.01). CONCLUSIONS: The development of endolymphatic hydrops, as indicated by an enlarged SP:AP, is part of the progression of Meniere's disease. The longer the duration of the disease, the more likely the SP:AP ratio will be enlarged. These findings indicate that endolymphatic hydrops as detected by ECoG was not reversed in this study by the treatments used. Despite the absence of definitive spells of vertigo in most patients, endolymphatic hydrops as evidenced by an enlarged SP:AP ratio persisted.

Adolescent↗

PubMed1997

Cochlear microphonics in Ménière's disease.

The pathophysiology of hearing deterioration in Ménière's disease (MD) is unclear. Hair cell loss has been proposed to be the cause of severe hearing loss in Ménière's disease. The cochlear microphonic (CM) is known to be the receptor potential of the outer hair cells in the cochlea. This study measured the CM in Ménière's disease and investigated its relationship with the degree of hearing impairment and endolymphatic hydrops. Transtympanic electrocochleography (ECoG) using rarefaction (RAR) and condensation (CON) tonebursts at 1 kHz was performed on 130 ears of 119 patients. Ninety six ears were diagnosed to have MD and 34 were diagnosed non-Ménière's disease (NMD). The mean amplitude of the CM was 33.10 +/- 46.04 microV in the MD group and 13.15 +/- 12.77 microV in the NMD group (p < 0.001). Enlarged negative summating potential and action potential ratios (SP:AP > 40%) were found in 81.3% of the MD group and 17.6% of the NMD group. In the MD group, the CM in the group with an enlarged negative SP was 36.98 +/- 49.78 microV, and 16.31 +/- 15.88 microV in the group without (p < 0.01). The CM was 34.33 +/- 49.28 microV in the pure-tone average (PTA) < or = 25 dB group, 46.97 +/- 58.31 microV in the 26-40 dB group, 29.12 +/- 42.62 microV in the 41-70 dB group, and 26.20 +/- 22.41 microV in the > 70 dB group (p > 0.05). The CMs in 11 pairs of MD ears and sensorineural hearing loss (SNHL) ears with matching hearing (MD 44 dB, SNHL 45 dB) were measured. They were 71.42 +/- 75.94 microV and 7.90 +/- 5.89 microV, respectively (p < 0.01). Our study shows that the CM is higher in ears with endolymphatic hydrops, evidenced by an enlarged SP:AP ratio, than ears without and the CM shows no statistical difference in groups with different levels of hearing loss. These findings suggest that hearing loss with a large CM in Ménière's disease patients may be the result of an alteration of cochlear mechanics and only severe hearing loss with a small CM is caused by hair cell loss. The CM measurement, to evaluate the hair cell status, may be helpful in identifying patients whose hearing may be recoverable if the underlying hydrops can be corrected. Our data do not permit the conclusion that an enlarged CM can be used in the diagnosis of MD.

Adult↗