Text Box: The role of extracellular potassium in the transduction process is well documented. Aside from contributing to the high endolymphatic fluid potential, the activities of apoptotic enzymes like caspaces and nucleases are K+ dependent, and abnormality of potassium channels is the main underlying factor for non-syndromic recessive hereditary SNHL (DFNA2). There has been mixed report on the overall effect of high extracellular potassium on hair cells, and to clear this fog, a recent animal study from Germany (Mazurek et al, Hearing Research, Volume 215, Issues 1-2 , May 2006, Pages 31-38  ) designed to examine the combined effects of high extracellular K+ concentrations and hypoxia/ischemia on HC vulnerability reported that in experimental rats, high K+ may not be as toxic to hair cells as hitherto thought.  Abstract:Several studies indicate that an increase in the extracellular potassium (K+) concentration is a factor exerting a damaging effect on cochlear hair cells (HCs). The present study was designed to examine the effects of high extracellular K+ concentrations on the HCs under normoxic and ischemic conditions. Organotypic cultures of the organ of Corti of newborn rats were exposed to normoxia and ischemia at K+ concentrations of 5–70 mM in artificial perilymph for 3–4 h. The number of IHCs and OHCs in the apical, medial and basal parts of the cochlea were counted 24 h later. The work resulted in two main findings: (1) extracellular K+ concentrations of 30–70 mM had no effect on the HCs under normoxic conditions; (2) under ischemic conditions, a clear HC loss, mainly in the medial and basal cochlear parts, was observed at 5 mM K+ as previously reported. In contrast, a high extracellular K+ concentration strongly attenuated the HC loss. This effect nearly completely disappeared by the addition of both eosin, an inhibitor of the plasma membrane calcium ATPase (PMCA), and linopirdine, an inhibitor of the KCNQ4 channel, indicating that a normal activity of the PMCA and the KCNQ4 channels are key factors for HC survival under ischemia and depolarizing conditions.   . Text Box: Editor's Choice:    High K+ and Hair Cells Toxicity...? Text Box: Abreast of Ear, Nose, Throat, Head & Neck Advances

Text Box: Volume 3, N0. 10 Text Box: June 11, 2006

Text Box: Otorhinolaryngology News

Text Box: Inside This Issue · High K+ & HC Toxicity · Early-onset NPC & pigmentation · TinTinnitus & Psycho-illumination *     Case of the Week

 

 

 Case Review

 Clinical Photo of The Week

 

A 41-year old male presented with right persistent frontal headache associated with right hemifacial pain. He had no significant medical history and no associated ophthalmological  or nasal symptoms. Clinical examination of the ear, nose, throat, head & neck was negative. MRI-Scan revealed the feature demonstrated in this radiograph. Lateral rhinotomy with medial maxillectomy excision biopsy of the mass was negative for malignancy. There has been complete resolution of headache / facial pain since 4 months following surgery

 

     What is the Diagnosis?
Text Box: Coming Events of Importance to Otorhinolaryngologists in Africa

1.          8th International Otology Course of the Jean Causse Ear Clinic June 22-24, 2006; Béziers, France

2. 110th American Academy of ORL, Head & Neck Surgery Annual Meeting & OTO EXPO, September 17-20, 2006; Toronto, Canada.

3. 42nd South African ENT Congress joint meeting with the British Association of Otolaryngology - Head & Neck Surgery, October 29-November 1, 2006; Cape Town, South Africa.

4.         16th Annual oto-rhino-laryngological society of Nigeria (ORLSON) General Meeting & Scientific Conference; November 22nd - 25th, 2006; Kaduna, Nigeria

5.         Faculty of Otolaryngology, National Postgraduate Medical College of Nigeria, 2nd Temporal Bone Dissection Course for Residents. Duration: 10th - 21st July (2 batches), 2006. Venue: Temporal Bone Room, LUTH, Idi-Araba, Nigeria. Contact: balseze@yahoo.com or aosomefun@yahoo.com. Deadline for registration: July 3, 2006

The issue of what to do with patients with perplexing tinnitus not responsive to all conventional measures was taken to a new dimension by this study also from Germany (Tonnies S, HNO. 2006 Jun;54(6):481-6 ) that reported relaxation effect of photic stimulation in such patients

Abstract: The therapeutic effect of applying photic stimulation was evaluated in a sample of 17 patients with chronic tinnitus. The employed optical stimulation technique triggers the activity of brain waves and induces deep relaxation characterized by increased EEG activity in the theta and delta spectrum. The expected therapeutic effect beyond relaxation was a decrease in subjective tinnitus distress and further improvements in well-being.All patients received ten applications of photic stimulation, each lasting 30 min. Every application markedly increased the peripheral blood circulation, thus indicating a relaxation effect. The emotional and cognitive impairments as well as the subjective tinnitus distress significantly decreased during treatment while sleep disturbances showed a tendency towards improvement. Overall, tinnitus distress markedly decreased and general well-being improved. The photic stimulation technique is proposed as a relief for tinnitus patients who do not respond to conventional relaxation techniques.

 

     Journal Watch :Tobacco-Pouch Suture Technique for Vascular lesion of the lip in Enugu, Oji et al, 2006

  1.  Reviewers wanted for otolaryngology news journal's watch page. If you are an Otolaryngologist in Africa and will like to be our journal reviewer, please feel free to email orl-mailer@otolaryngologyinafrica.net

  2.   DODA 2006, capable of advanced hearing measure, and also paediatric hearing assessment is being developed. If you requested for and got a free copy of DODA, you may also look out for this latest version dubbed DODA-i, as well as for an additional page on outcome of hearing assessment using DODA.

 3.  A subweb of this site, dedicated to online publications of otorhinolaryngological grand round presentations across Institutions all over Africa will soon take off. The subweb once active can be accessed at http://www.otolaryngologyinafrica.net/grandround/ . Watch out, and please take advantage of this to send in your grand round presentations. Also watch out for online discussion forum for discussion of issues concerning otolaryngologists, but not really of clinical nature at http://otolaryngologyinafrica.net/discussionforum/ 

 Till Next Week,

 Biodun

This is a free email newsletter circulating to Otolaryngologists in Africa, and interested Otolaryngologists elsewhere. If you know anyone interested in receiving this free newsletter, feel free to forward a copy to such person or encourage them to email orl-mailer@otolaryngologyinafrica.net for free subscription

 

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