Identification of a new locus for autosomal dominant non-syndromic hearing impairment (DFNA7) in a large Norwegian family.

Hereditary hearing impairment affects about 1 in 1000 newborns. In most cases hearing loss is non-syndromic with no other clinical features, while in other families deafness is associated with specific clinical abnormalities. Analysis of large families with non-syndromic and syndromic deafness have been used to identify genes or gene locations that cause hearing impairment. The present report describes a large Norwegian family with autosomal dominant non-syndromic, progressive high tone hearing loss with linkage to 1q21-q23. A maximum LOD score of 7.65 (theta = 0.00) was obtained with the microsatellite marker D1S196. Analysis of recombinant individuals maps the deafness gene (DFNA7) to a 22 cM region between D1S104 and D1S466. The region contains several attractive candidate genes. This report supports the idea of extensive genetic heterogeneity in hereditary hearing impairment and represents the first localization of a deafness gene in a Norwegian family.

Patient performance with two types of multiple electrode intracochlear implant.

The functional results of 9 persons implanted with the Symbion Ineraid and 8 persons implanted with the Nucleus cochlear implant with the F0, F1, F2 coding strategy are reported. All patients were postlingually totally deaf, the patients implanted with the Symbion Ineraid were all above 40 years of age, while the Nucleus patients were with one exception under 40 years of age. The CID Everyday Sentences Test, the Helen Test and the Speech Tracking Test showed that all patients improved their communication skills when sound through the implant was added to lip-reading. The patients' ability to understand without lip-reading was tested with the CID everyday sentences test, with the Helen test, with spondees, with three-choice vowels and with a consonant confusion test. These showed that all 9 Symbion Ineraid patients achieved some degree of open speech understanding. Four of the 8 Nucleus patients achieved some degree of open speech understanding. Difference limen tests for intensity and frequency indicated that 2 of the Nucleus patients who did not achieve open speech understanding probably had extensive cochlear nerve damage, while the remaining 2 Nucleus patients without open speech understanding had good frequency and intensity discrimination.

[Laser surgery in otorhinolaryngologic diseases]. / Laserkirurgi ved sykdommer i øre-nese-halsregionen.

This survey is based on our own experiences and a study of the literature. The CO2 laser has certain advantages in the surgical treatment of otosclerosis, both in the primary operation and in reoperation. In rhinal surgery the argon laser has been used with good results in Osler's disease. Laser surgery is not recommended for vasomotoric rhinitis and polyposis. The CO2 laser has improved the quality of treatment of laryngeal papilloma. With high precision and minimal bleeding the postoperative voice is better than with conventional surgery. The CO2 laser can also be used to exstirpate small malignant tumours of the tongue and leukoplasia of the oral mucosa. Healing is rapid and involves relatively little pain. The postoperative functional result is usually good, due to moderate formation of scars.

Experimental laryngeal reinnervation by phrenic nerve implantation into the posterior cricoarytenoid muscle.

Under general anaesthesia, 5 dogs underwent sectioning of the right recurrent nerve followed by implantation of the phrenic nerve into the posterior cricoarytenoid (PCA) muscle. Some 6-7 months later the dogs were sacrificed after registration of vocal cord motility. Still photographs and movie film of the larynx were taken during quiet and forced respiration and at electrical stimulation of the implanted phrenic nerve. The PCA and vocal muscles were removed for histochemical studies. We found practically no abductory movement of the vocal cord on the reinnervated side, either during quiet or forced respiration. During forced inspiration there was, however, a slight medial bowing of the right vocal cord. At electrical stimulation there was a sphincteric movement of the entire larynx. Histochemistry showed a reinnervation picture of both the PCA and the vocal muscles on the experimental side. The conclusion drawn from this study is that axonal escape, probably from the implantation site, results in an unwanted reinnervation of laryngeal adductor muscles, which neutralize the abducting effect of the PCA muscle during inspiration. This method therefore does not seem to be suitable as a treatment alternative for bilateral recurrent nerve paralysis.

Experimental laryngeal reinnervation by phrenic nerve implantation into the posterior cricoarytenoid muscle.

Under general anaesthesia, 5 dogs underwent sectioning of the right recurrent nerve followed by implantation of the phrenic nerve into the posterior cricoarytenoid (PCA) muscle. Some 6-7 months later the dogs were sacrificed after registration of vocal cord motility. Still photographs and movie film of the larynx were taken during quiet and forced respiration and at electrical stimulation of the implanted phrenic nerve. The PCA and vocal muscles were removed for histochemical studies. We found practically no abductory movement of the vocal cord on the reinnervated side, either during quiet or forced respiration. During forced inspiration there was, however, a slight medial bowing of the right vocal cord. At electrical stimulation there was a sphincteric movement of the entire larynx. Histochemistry showed a reinnervation picture of both the PCA and the vocal muscles on the experimental side. The conclusion drawn from this study is that axonal escape, probably from the implantation site, results in an unwanted reinnervation of laryngeal adductor muscles, which neutralize the abducting effect of the PCA muscle during inspiration. This method therefore does not seem to be suitable as a treatment alternative for bilateral recurrent nerve paralysis.

The human posterior cricoarytenoid (PCA) muscle and diaphragm. A histochemical comparison as a basis for reinnervation attempts.

PCA (posterior cricoarytenoid) muscles and biopsies from the SCM (sterno-cleidomastoid) muscles as well as the diaphragm were serially sectioned and incubated for myofibrillar ATPase and selected metabolic enzymes. The three main fibre types were present in all muscles, although some PCA muscles seemed to lack IIB fibres. The mean fibre type pattern of the PCA muscle was 57% type I, 36% type IIA and 7% type IIB, as compared with 42% type I, 42% type IIA and 16% type IIB in the diaphragm. All fibre types of the PCA muscle and the diaphragm were significantly more oxidative and less glycolytic than the corresponding SCM muscle fibres. Most striking was the finding of high 3-HBDH activity in the PCA and diaphragm muscle fibres, especially in type I.

Functional results after experimental reinnervation of the posterior cricoarytenoid muscle in dogs.

The purpose of the present investigation was to test and compare three different types of experimental posterior cricoarytenoid (PCA) muscle reinnervation. Dogs were subjected to reinnervation by the recurrent nerve itself (self-reinnervation) (n = 6), by the ansa cervicalis nerve (n = 5) or by the phrenic nerve (n = 5). In all but three of the self-reinnervation cases the adductor branch of the nerve was cut and ligated. Three to seven months postoperatively--depending upon the experimental approach--the animals were anesthetized and the function of the vocal cords was tested, visually evaluated and photographed. In the self--reinnervated larynges there were no observable movements on the reinnervated side during quiet inspiration, while during forced inspiration there were small but inconsistent movements. In the larynges reinnervated by the ansa cervicalis nerve no movements could be observed on the reinnervated side during either quiet or forced respiration. In four out of five larynges reinnervated by the phrenic nerve there were larger excursions on the reinnervated side as compared to the normal side during quiet respiration. During forced inspiration the excursions increased on both sides, but relatively more on the normal side. In all experiments indirect electrical stimulation gave large excursions on the experimental side indicating successful reinnervation. It is concluded that the phrenic nerve appears to be the best alternative if reinnervation of the PCA muscle in paralyzed larynges is attempted.

A histochemical evaluation of experimentally reinnervated canine laryngeal muscles.

Sixteen dogs underwent different types of experimental reinnervation procedures of the posterior cricoarytenoid (PCA) muscle - reinnervation by the recurrent nerve itself (self-reinnervation) (n = 6), by the ansa cervicalis nerve (n = 5) or by the phrenic nerve (n = 5). After functional evaluation the normal left and the reinnervated right PCA muscles were removed for histochemical analysis. Cryostat sections were incubated for actomyosin ATPase, NADH-TR and alpha-GPDH. All muscles showed microscopical evidence of successful reinnervation. There was a slight change in the muscle fiber type composition in the reinnervated muscle as compared to the normal side. Incubations for the NADH-TR and alpha-GPDH showed less staining intensity in the reinnervated muscles. The histochemical differences between normal and reinnervated muscles were small, however, and probably of minor importance with regard to the function of the muscles.

The histochemistry of the posterior cricoarytenoid (PCA) muscle in the dog, compared with the diaphragm, the sternothyroid and the sternomastoid muscle.

The canine posterior cricoarytenoid (PCA) muscle was compared histochemically with pieces of the diaphragm (Dia), an infrahyoid muscle (the sternothyroid, ST), and with a reference skeletal muscle (the sternomastoid, SM) taken from the same animal. The muscle fibre type composition in the PCA, Dia and ST differed very little and showed a slight type II preponderance. In the SM there was a strong type II preponderance. A subgrouping of the type II muscle fibres could not be carried out in any of the muscles. The oxidative activity was greater in the PCA than in the other three muscles and greater in type I than in type II fibres for all muscles except the Dia. In the Dia, some type I fibres had a larger cross-sectional area and showed a greater oxidative activity and contained less glycogen than the rest of the type I fibres in the muscle. These fibres seemed to represent a separate subgroup of type I fibres possibly serving quiet respiration.

Histochemical characteristics of the tensor tympani muscle in relation to the medial gastrocnemius muscle of the cat.

Serial 10-micron cryostat cross-sections of the tensor tympani muscle and of the medial gastrocnemius muscle from adult domestic cats were incubated for myofibrillar ATPase, NADH tetrazolium reductase (NADH-TR), succinic dehydrogenase (SDH), malate dehydrogenase (MDH) and menadione-linked alpha-glycerophosphate dehydrogenase (alpha GPDH). The optical density of individual tensor tympani and gastrocnemius muscle fibres after different incubation procedures was measured photometrically. The absorbance values of the tensor tympani fibres were related to the values of the type I, type IIA and type IIB fibres of the gastrocnemius muscle. Only two different types of fibre could be demonstrated in the tensor tympani, one type resembling the type I and another resembling the type IIA of the gastrocnemius muscle. The findings are discussed in relation to other, recent immunohistochemical studies on cat tensor tympani muscle fibres.

Actomyosin ATPase activity of human laryngeal muscles.

The muscles from seven human larynxes removed by laryngectomy have been examined for actomyosin ATPase by histochemical methods. The various muscles contained a mixture of ATPase low (type I) and ATPase high (type II) muscle fibres. The thyreoarytenoid muscle had the highest proportion of type II fibres (65%) and the posterior cricoarytenoid muscle had the highest proportion of type I fibres (67%). The other laryngeal muscles had intermediate valves. All human laryngeal muscles had a higher percetage of type I fibres than the corresponding muscles in animals so far examined, a finding which may be related to the development of speech.

[Surgical correction of vocal cord synechia (author's transl)]. / Cirurgische Korrektur bei Synechien der Stimmbänder

Anterior webs of the larynx, whether congenital or traumatic in origin, are conventionally treated by excision and subsequent interposition of a stent between the raw surfaces of the defect to prevent regrowth of the web. The present paper describes a new technique which does not require interposition of a stent. The web is divided through a laryngofissure and adjacent connective tissue is removed. The cut raw surfaces of the vocal cords are covered by the adjacent mucosa, which is carefully mobilized, adapted and sutured with interrupted silk sutures. The method described has been used in eight patients, with a good result obtained in seven of the patients. In the eighth patient, post-tranumatic scars with web formation were removed so that the condition was improved but not completely corrected.

Application of glass capillary-column gas chromatography-mass spectrometry to the studies of human diseases.

Open-tubular glass capillary columns have been used in gas chromatography in combination with mass spectrometry (GC-MS) and computer methods to study human diseases. Patients with maple syrup urine disease excrete not only alpha-keto and alpha-hydroxy acids but also six other metabolites which hitherto have been overlooked. The GC-MS methods demonstrated that a group of patients suffering from hereditary progressive loss of hearing have an impaired metabolism of leucine, leading to the accumulation of 3-hydroxyisovaleric acid and 3-methylcrotonylglycine. GC using the capillary columns proved suitable for mapping of the carbohydrate profile of human seminal fluid and for the analyses of organic compounds accumulating in human adipose tissue. The high resolving power and long life of the glass capillary columns suggest that they will be valuable in the diagnosis and study of human disorders.