title: Summating potential and action potential ratio in Meniere's disease before and after treatment.
abstract: 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.
  
  
  METHODS
  The study design was a retrospective case review.
  
  
  METHODS
  The study was conducted at an otology-neurotology referral center.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
authors.affiliation: Shea Clinic, Memphis, Tennessee 38119, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Orchik
authors.forename: J J
authors.initials: JJ
authors.lastname: Shea
authors.forename: N N
authors.initials: NN
authors.lastname: Ge
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001300:Audiometry, Evoked Response / Q000379:methods; D018450:Disease Progression; D018159:Endolymphatic Hydrops / Q000209:etiology; D004713:Endolymphatic Shunt / Q000379:methods; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000150:complications / Q000175:diagnosis* / Q000628:therapy*; D008875:Middle Aged; D012189:Retrospective Studies; D013307:Streptomycin / Q000627:therapeutic use*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D013307:Streptomycin