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Biomedical subjects

J Helms

Publications and source records attributed to J Helms.

At least 37 records · Page 2Linked to original sources
PubMed1997

Stapes surgery in osteogenesis imperfecta patients.

Osteogenesis imperfecta (OI), or the Van der Hoeve-de Kleyn syndrome, is a heterogeneous group of connective tissue disorders. The key features in this disease are bone fragility with a tendency to spontaneous fractures and deformations. The classical traid of symptoms involves a conductive and/or sensorineural hearing impairment together with a tendency to spontaneous bone fractures and blue sclerae. Between January 1988 and December 1994, ear surgery was performed on eight ears of six OI patients who presented with mixed hearing loss preoperatively. Pathological changes observed in the middle ear were atrophy and/or fractures of the stapedial crura in combination with thickening and fixation of the stapes footplate. Partial stapedectomy was performed in seven cases and a neo-window was created in the promontory of one patient when an overhanging facial canal obscured visualization of the oval window niche. Pre- and postoperative bone conduction thresholds did not differ in any of the patients. Postoperatively, mean values of the air-bone gap in the main speech frequency range were below 10 dB. Functional results following stapes surgery in patients with otosclerosis during the same time interval (n = 857) did not differ significantly. These data indicate that stapes surgery in OI patients can be performed with the same functional predictability as in otosclerosis patients, even though the underlying etiology is considerably different.

Adult↗
PubMed1997

[Ionomer cement prostheses in reconstructive middle ear surgery].

Animal experiments with microbiologic examinations and studies in cell cultures have shown that ionomer cement is a biocompatible and biostable bone replacement material in the head and neck region. Clinical and functional results of its use in the human middle ear have proven to be satisfactory during a maximal period of 2.5 years observation. The present trial was continued in order to determine the long-term behavior of ionomer cement (Ionos partial and total ossicles) after reconstruction of the ossicular chain. The ossicular chain was reconstructed in 343 cases and included various losses of one or more of the ossicles (i.e., incus, incus and malleus, incus and stapes superstructure, and malleus, incus and stapes superstructure). Follow-up extended over a maximum period of 5.5 years. Patients were examined under a surgical microscope and a pure-tone audiogram was performed at regular intervals. Clinical and audiological results were obtained 3 months postoperatively in all reconstructive procedures performed (partial and total ossicular replacement prostheses). These were mainly stable but revision surgery was necessary in 9% of the cases. In 5% the prosthesis was displaced and in 3% the prosthesis had partially migrated through the eardrum. Complete rejection of the implants was observed in the course of infections in 1% of the cases. Ionomer cement as a bone replacement material was found to have all required criteria for its use in the middle ear (biocompatibility, biostability, stable audiologic results and easy workability). These findings show that ionomer cement can be recommended in all cases of ossicular reconstruction.

Adolescent↗
PubMed1997

Performance of ionomeric cement (Ionocem) in the reconstruction of the posterior meatal wall after curative middle-ear surgery.

The hybrid bone-substitute ionomeric cement is suitable for restoring the original anatomy of the posterior canal wall. During a four-year period the posterior meatal wall was rebuilt with ionomeric cement in 74 patients. The canal wall was totally rebuilt in 38 patients, two-thirds rebuilt in 22 cases, and one-third rebuilt in 14 cases. On the meatal side, the canal wall was covered by a musculo-periosteal (Palva) flap. In the majority of cases, the drum was closed with (cartilage)-perichondrium. Revisions were performed in 27 patients (due partially to cholesteatoma, and/or poor visualization of radical mastoidectomy cavities). The ears were non-infected at the time of operation. Permanent epithelialization of the bone replacement material was achieved in 57 cases, with secondary closure of a cutaneous defect of the meatal wall being required in six cases. The auditory canal wall had to be removed in 17 patients owing to deficient soft-tissue coverage, persistent inflammation, and/or partial adhesive processes with development of cholesteatoma. In terms of surgical technique, utilization of the material over a follow-up period of maximally seven years proved it to be a sophisticated procedure for reconstructing the meatal wall. Despite the finesse of the surgical technique employed, the overall failure rate of 31 per cent was inadmissibly high. Implantation of the material should therefore be restricted to middle ears with permanent ventilation and no trace of infection.

Adult↗
PubMed1997

Refined mastoid reconstruction with the pedicled postauricular perichondrial flap.

Successful canal wall reconstruction after open cavity surgery may be compromised by both immediate (graft dehiscence and infection) or delayed (graft retraction, absorption, and extrusion) complications. Many of the healing problems following canal wall reconstruction are related to incomplete soft tissue coverage of the graft and limited blood supply. Under these conditions, we sought to increase graft viability with a broad-based perichondrial flap developed from the posterior surface of the auricle. The flap was used over a period of 3 years at a tertiary referral center in 36 cases of canal wall reconstruction in conjunction with composite grafts of cartilage and perichondrium. The patients ranged in age from 12 to 63 years and in all cases had undergone a canal down tympanomastoidectomy that was reconstructed either primarily or secondarily. The canal wall was successfully reconstructed in 35 of 36 ears. These results demonstrate a reduction in our dehiscence rate from 10 to 3% since the introduction of the perichondrial flap. With the perichondrial flap, we were consistently able to achieve better soft tissue coverage of the composite cartilage graft, eliminate lateral graft dehiscence, and encourage reepithelization of the canal. By implication, we believe this flap provides a source of nutritional support for the free cartilage graft as well as the overlying skin.

Adolescent↗
PubMed1997

Optimization of channel number and stimulation rate for the fast continuous interleaved sampling strategy in the COMBI 40+.

OBJECTIVE: To investigate the interrelation between number of channels and stimulation rate in the continuous interleaved sampling strategy (CIS). SUBJECTS AND METHODS: Three of the first recipients of the new COMBI 40+ cochlear implant participated in consonant, vowel, number, and sentence tests. Speech understanding was evaluated for different combinations of number of active channels from two to twelve and stimulation rate per channel between 1,515 and 9,090 pulses per second. RESULTS: The results indicate that the optimum number of active channels is not necessarily the maximum number of usable channels.

Adult↗
PubMed1996

Effect of estrogen withdrawal on blood pressure and insulin resistance in sucrose-fed juvenile rats.

We have previously shown that juvenile Sprague-Dawley rats, fed a diet in which complex carbohydrates are replaced by sucrose, develop insulin resistance and hypertension. These conditions develop despite the absence of genetic predisposition to either. When studied with the euglycemic hyperinsulinemic clamp technique, these rats have reduced insulin-stimulated glucose utilization, but normal suppression of hepatic glucose output. In the young sucrose-fed rats, it was noted that the degree of blood pressure elevation was greater in males than in females. The purpose of this study was to test the hypothesis that estrogen withdrawal increases insulin resistance and hypertension. Female rats were randomized at weaning (3 weeks of life) to receive control diet or sucrose diet. Animals were assessed with weekly weight and indirect tail-cuff blood pressure. At 8 weeks of life, the sucrose-fed rats were randomized to receive bilateral oophorectomy or sham surgery (anesthesia and uterine horn exposure without removal of the ovaries). At 13 to 14 weeks of life, all animals were fasted overnight, and had an oral glucose tolerance test while conscious. Weight and weight gain were not different among the groups over the 11 week study period. Animals fed the sucrose diet developed significantly higher blood pressure than animals fed the control diet; oophorectomized animals had higher blood pressure than sham-operated animals (P <.0001). Sucrose-fed oophorectomized animals developed fasting and glucose-stimulated hyperinsulinemia. Estrogen withdrawal augments blood pressure in juvenile rats made insulin resistant and hypertensive with a sucrose diet. Estrogen withdrawal in these animals also induces fasting and glucose-stimulated hyperinsulinemia, which are signs of worsening insulin resistance. Androgen:estrogen imbalance increases metabolic dysfunction and worsens hypertension in this animal model.

Animals↗
PubMed1995

[Modern aspects of tympanoplasty. An overview].

The cholesteatoma should be removed with a canal wall down-technique in small mastoids. In patients with well or highly pneumatized temporal bones the reconstruction of the posterior canal wall is recommended after complete removal of the matrix. Myringoplasty is mainly performed using perichondrium. In highly damaged middle ears the cartilage palisade technique is indicated. The reconstruction of the ossicular chain performed using modern artificial materials.

Cholesteatoma, Middle Ear↗
PubMed1995

[Facial nerve abnormalities in malformed temporal bone].

Between 1987 and 1993, 4500 tympanoplasties and stapedectomies were performed at the ENT Department of the University of Würzburg. In 134 cases, surgery was performed for malformation of the middle ear. The surgery reports of these patients were analyzed for anomalies of the facial nerve. Forty cases (29.9%) showed an anomaly of the facial nerve, more often congenital aural atresia or major malformation (30.4%) than minor malformation (29.1%). The most frequent finding was a dislocation of the nerve over the oval niche and resulting narrowing of the oval window (22 cases). Eleven cases showed the facial nerve without bony covers, in two cases there was an exposed nerve over the oval niche. An acute-angled course between horizontal and vertical segment in the mastoid, doubling of the nerve, lateralization of the mastoidal segment, and anterior shift of the Fallopian canal in the mastoid were observed once. To reduce the risk of facial nerve injury, high resolution CT scan studies should be performed before surgery in the presence of congenital aural atresia.

Diagnosis, Differential↗
PubMed1995

Hearing preservation in acoustic tumor surgery: results and prognostic factors.

A retrospective study was conducted to assess the hearing results in patients who underwent acoustic neuroma removal via the middle fossa approach. A statistical correlation of results with preoperative clinical and audiological data determined if any prognostic indicators could be associated with successful hearing preservation. Of 93 patients included in the study, useful hearing was preserved in 54 (58%), and hearing was preserved near preoperative levels in 42 (45%). The potential for hearing preservation appeared to be inversely related to the size of the acoustic tumor, with hearing preserved in 39 (60%) of 65 patients with tumors less than or equal to 0.5 cm extension into the cerebellopontine angle. Preoperative hearing levels and electronystagmography seemed to have no prognostic value. However, auditory brainstem response showed that a wave V latency of less than 6.8 msec was associated with an increased chance of hearing preservation, and the presence of vertigo as a preoperative complaint appeared to be a good prognostic indicator of successful hearing preservation.

Adult↗