Biomedical subjects

Michael H Fritsch

Publications and source records attributed to Michael H Fritsch.

6 recordsLinked to original sources

PubMed2006

Magnetic properties of middle ear and stapes implants in a 9.4-T magnetic resonance field.

HYPOTHESIS: A 9.4-T magnetic resonance (MR) field may cause motion displacement of the middle ear and stapes implants not previously observed with 1.5- and 3.0-T magnets. BACKGROUND: Publications have described the safety limitations of some otologic implants in 4.7-T field and resulted in several companywide patient safety-related recalls. To date, no studies have been reported for otologic implants in a 9.4-T MR field nor have comparisons been made with 4.7-T field strengths. METHODS: Twenty-three commonly used middle ear and stapes prostheses were selected and exposed to 9.4-T MR fields in vitro within petri dishes, and eight of the 23 implants were further studied ex corpus in human temporal bones (TBs) in a 9.4-T MR field. This study has been approved by the institutional review board. RESULTS: Eight prostheses in petri dishes grossly displaced at 9.4 T, three of which had not previously moved in either the 1.5- or 3.0-T magnets. The eight TB preparations showed no avulsions or motion indicators after exposure at 9.4 T. CONCLUSION: Middle ear and stapes implants can move dramatically in petri dishes at 9.4-T MR field, more so than at 1.5 and 3.0 T. The absence of avulsions in the TB group strongly suggests that the surgical means used to fixate the middle ear implants to the middle ear structures successfully overcomes the magnetic moment produced at MR field strengths up to 9.4 T. The use of MR imaging is not contraindicated by this study's findings.

Cadaver↗

PubMed2005

Ferromagnetic movements of middle ear implants and stapes prostheses in a 3-T magnetic resonance field.

HYPOTHESIS: A 3-T magnetic resonance field may cause motion or displacement of middle ear implants not seen in studies with 1.5-T magnets. BACKGROUND: Previous publications have described the safety limitations of some otologic implants in 1.5-T magnetic resonance fields. Several company-wide recalls of implants were issued. No studies to date have been reported for otologic implants within a 3-T magnetic resonance field, nor have there been comparisons with a 1.5-T field strength. METHODS: Eighteen commonly used middle ear implants and prostheses were selected. In Part 1, the prostheses were placed in Petri dishes and exposed to a 3-T magnetic resonance field. In Part 2, the particular prostheses that showed movement in Part 1 were placed into their intended use positions within temporal bone laboratory specimens and exposed to a 3-T field. Both parts were repeated in a 1.5-T field. RESULTS: In Part 1, three prostheses moved dramatically from their start positions when exposed to the 3-T magnetic resonance field. In Part 2, the three particular prostheses that showed movement in Part 1 showed no gross displacement or movement from their start positions within the temporal bone laboratory specimens. No implants moved in the 1.5-T field in either Part 1 or Part 2. CONCLUSION: Certain stapes prostheses move dramatically in Petri dishes in 3-T fields. When placed into temporal bone laboratory specimens, the same prostheses show no signs of movement from the surgical site in a 3-T field, and it appears that the surgical position holds the implants firmly in place. Results of published 1.5-T field studies should not be used directly for safety recommendations in a 3-T magnetic resonance. Heat, voltage induction, and vibration during exposure to the magnetic resonance fields should be considered as additional possible safety issues. Preference should be given to platinum and titanium implants in manufacturing processes and surgical selection.

Contraindications↗

PubMed2004

Incisionless otoplasty.

Otoplasty surgery for correction of the "lop" protuberant ear deformity continues to evolve. A noninvasive method for achieving normal appearance and physiology for the protuberant ear pinna is presented. Incisionless Otoplasty surgery, involving a combined cartilage scoring procedure and a percutaneously placed retention suture procedure, creates a predictable and permanent correction of the missing antihelical fold. In addition, treatment of the protruding conchal bowl by endoscopic techniques further enhances the cosmetic appearance. A long-term follow-up period of over 10 years gives perspective on the efficacy of the operation.

Ear Cartilage↗

PubMed2003

Salivary stones: innovative techniques in diagnosis and treatment.

During the last decade, minimally invasive and nonsurgical techniques of diagnosing and treating salivary gland duct stones have rapidly evolved. Physicians have developed alternative treatments beyond the sole use of invasive conventional surgery. Techniques and equipment have been specifically developed to deal with ductal lithiasis. Salivary duct endoscopy, endoscopic instrumentation, and intra- or extracorporeal lithotripsy have proven themselves to be efficacious in most cases involving ductal stones. Current algorithms for treatment combine conventional surgical, minimally invasive, and nonsurgical strategies to produce the least invasive and best-tolerated outcomes for each individual patient.

Humans↗

PubMed2002

Transient-evoked otoacoustic emissions from ears with tympanostomy tubes.

OBJECTIVE: Otoacoustic emissions (OAEs) are low-level acoustic signals which emanate from the cochlea and can be recorded in the ear canal. The two types of OAEs are spontaneous and evoked otoacoustic emissions. METHODS: In this retrospective study, transient-evoked otoacoustic emissions (TEOAEs) were measured in 385 ears from 204 children with normal hearing and tympanostomy tubes. RESULTS: The results indicate that, when using the Quick Screen option on the Oto-Dynamics ILO88 Otoacoustic Emission Analyzer, postoperative TEOAEs were present at all measured frequencies in 81% of the ears. The remaining 19% of ears showed the absence of an observable emission at one or more of the measured response frequencies. The overwhelming factor contributing to an absent emission was insufficient stimulus energy at 4 kHz. The use of T-type tympanostomy tubes also appeared to decrease the probabilities obtaining normal TEOAEs in ears with normal peripheral auditory function. The use of grommet-type tympanostomy tubes, the type of middle ear effusion, the age and gender of the child, and the physical volume of the ear canal as measured by tympanometry with the tympanostomy tube patent and in place had negligible effects on the measurement of TEOAEs. CONCLUSIONS: Clinicians must be cautious when interpreting click-evoked TEAOEs if the patient has a T-tube in place and may need to modify this testing to rule out high-frequency hearing loss when using TEOAEs with these patients. For those patients who have tympanostomy tubes and fail to meet the "pass criteria" for TEOAEs at 4 kHz in the Quick Screen option, TEOAE should be repeated either in the Diagnostic mode or by using a 4 kHz tone-burst stimulus centered at 4 kHz to recover the loss of energy in this region due to the high-frequency roll-off of the stimuli used in the Quick Screen option.

Adolescent↗

PubMed2002

Reconstruction following lateral skull base surgery with introduction of facial incisionless reanimation surgery.

The large ablations needed to remove some lateral skull base pathologic conditions remain a challenge to the reconstructive surgeon. Major shortcomings abound despite significant development of surgical techniques and advances in the understanding of healing. The tremendous advances of the past 30 years with the dawn of major tissue transfer techniques, new biomaterials, and the use of surgical teams with enormous combined clinical knowledge bases have catapulted surgical reconstruction efforts. Progress has been tempered by the realization that normal tissue functions are still incompletely rebuilt. As work on tissue culture, genomic understanding, biomechanics, blood oxygenation substituted, and other research fronts progress and converge, newer and better ways of addressing lateral skull base reconstruction will arise.

Facial Nerve↗