[Lightening strike injuries of the ear]

Although lightning injuries are quite common, lightning-induced damage to the middle or inner ear and to the vestibular nerve has been reported in only a very few cases. Two case reports are presented: a 22-year-old woman and a 26-year-old man who experienced lightning injuries to several body parts including the ear. Pathophysiology, diagnostic criteria and treatment are discussed.

Effect of artificial airway on ear complications from hyperbaric oxygen

Hyperbaric oxygen treatment is associated with an increased risk of barotrauma to the tympanic membrane and middle ear. An artificial airway may compromise normal eustachian tube function and equilibration of middle ear pressures. This retrospective study was designed to evaluate the risk of middle ear complications in 267 patients receiving hyperbaric oxygen (HBO) therapy and to compare those with and without artificial airways. Charts of all patients were reviewed for middle ear and tympanic membrane complications and myringotomy tube placement. Eighteen of the 267 patients had artificial airways. Seventeen (94%) of these 18 patients developed middle ear or tympanic membrane complications, and 11 (61%) required tympanostomy tubes for pain, hemotympanum, or serous otitis. In contrast, 114 (45.8%) of the 249 patients without airways developed ear complications, and 53 (21.3%) required tympanostomy tubes. These results suggest that patients with an artificial airway who are receiving HBO therapy are at greater risk for developing tympanic membrane and middle ear complications than nonintubated patients. Similarly, patients with artificial airways receiving HBO frequently require placement of tympanostomy tubes.

Blast injury of the auditory system: a review of the mechanisms and pathology

Blast injury of the auditory system is uncommon and our knowledge incomplete. This article reviews the literature to date giving an account of the interactions of blast waves with the ear, the mechanisms of injury, the pathology, the clinical features, and an outline of management principles.

Evaluation of basic fibroblast growth factor in tympanic membrane repair

Basic fibroblast growth factor (bFGF) has been shown to enhance speed of wound repair at a number of anatomic sites. This study presents an evaluation of bFGF in a model of acute tympanic membrane (TM) perforation in order to assess rate of healing as well as structural and functional outcome. Perforations were created in the tympanic membranes of rats, then allowed to heal in the presence of topically applied bFGF with the opposite ear serving as a control. The growth factor was applied in repeated doses beginning 2 days after creation of the TM defect. The treated ears healed faster by an average of 4.0 days. The healed tympanic membranes were assessed using tympanometry and light microscopy. Structurally and functionally, the healed tympanic membranes were similar to the controls. The observed results indicate that bFGF promotes accelerated healing and restoration of normal architecture in acute TM defects.

Stapedius reflex and EABR thresholds in experienced users of the Nucleus cochlear implant

Evoked auditory brainstem responses (EABR) and stapedius reflex thresholds were established in 7 experienced users of the Nucleus cochlear implant. Even using biphasic 400 microseconds/phase clicks for the EABR, responses were observed in only 5 patients; no stapedius reflex (SR) was seen in 3 patients, 2 of whom had a history of middle-ear disorder. The EABR threshold varied widely between subjective threshold and uncomfortable loudness level (ULL) for the same stimulus. The average SR threshold was found somewhat more consistently at 66% of the dynamic range between threshold and ULL, but grossly overestimated the most comfortable level (MCL) in most cases. To obtain equal loudness at the same current level we suggest that broad clicks (300 microseconds/phase) be used for EABR measurements, thus compensating for the lower repetition rate of EABR stimulus compared with the device fitting stimulus.

Fasciaform myringoplasty in children

OBJECTIVE

To evaluate the efficacy of fasciaform myringoplasty as a means to repair large tympanic membrane perforations in children.

DESIGN

Retrospective review of the records of 26 patients who underwent 29 consecutive fasciaform myringoplasty surgeries over a 47-month period. Patients were followed up from 2 to 47 months postoperatively.

SETTING

Academic tertiary care children's hospital.

PARTICIPANTS

Twenty-six patients (5 to 16 years old), with tympanic membrane perforations (25% to 95%) underwent a fasciaform myringoplasty procedure. The perforations were caused by extrusion of ventilation tubes (83%), deep retraction pockets, trauma, or repair after resection of cholesteatoma.

INTERVENTION

The surgery involves resection of the native tympanic membrane and annulus. A new tympanic membrane is formed from formaldehyde-fixed autogenous temporalis fascia and positioned.

OUTCOME MEASURE

Successful repairs, complications, and audiometric evaluations were analyzed. Fisher's Exact Test was used to compare complication rates by age.

RESULTS

Successful closure was accomplished in 69% of cases. Otitis media recurred in 52%. Ventilation tubes were reinserted in 24%; 28% resolved with antibiotics alone. When tubes were placed through the graft, small residual graft perforations resulted. Audiometric evaluation revealed improvement in pure tone average to less than a 20-dB hearing level in 77% and reduction of the air-bone gap to within a 20-dB hearing level in 90% of those cases (10/29) with complete audiometric data.

CONCLUSIONS

Fasciaform myringoplasty has proven to be a successful procedure for closing large tympanic defects and improving hearing acuity in the pediatric population. However, recurrent otitis media and eustachian tube dysfunction may continue. Rates of reperforation were statistically significantly higher in children 7 years old and younger. Conservative management of children in this younger age group is warranted.

Tympanic membrane perforation in survivors of a SCUD missile explosion

On February 25, 1990, an Iraqi SCUD missile exploded inside a building housing United States military personnel in Dhahran, Kingdom of Saudi Arabia. One hundred seventy-two individuals who were near the impact site at the time of the blast were interviewed and examined to determine blast injury to the ear. Tympanic membrane (TM) perforation was used as the clinical marker for aural blast injury. Thirty-four personnel had unilateral TM perforation and 28 had bilateral TM perforation. Eighty-six sustained sufficient injury to be hospitalized. Fifty-nine of hospitalized personnel (70%) had TM perforation. Of a total of 90 TM perforations, 39% were estimated to be 25% or less of the tympanic membrane surface area, 36% were 26% to 50%, 16% were 51% to 75%, and 10% were greater than 75%. Morphology of the perforations and estimated proximity to the blast were documented. Personnel distant from the blast, in open doorways or wearing headphones, had relative protection from TM perforation. Historic nuclear blast data were used to estimate the SCUD blast waveform based on measurements of the SCUD impact crater. A mathematical model based on the estimated waveform was validated against the actual field data by comparing the proximity and incidence of TM perforations in the SCUD missile explosion.

Exogenous heparin, topically administered, aids the remodelling of connective tissue in the healing of experimental tympanic membrane perforations

Heparin, in concentrations of 250, 2,500 and 25,000 IU, was applied topically to the edge of tympanic membrane (TM) perforations, standardized in size, once daily until the perforation had closed. At 2 months, the animals were killed and the TMs subjected to otomicroscopic and light microscopic studies. The day that closure of the TM perforations was complete (median 8 days) was the same for the various heparin groups as for the sterile water-treated controls. However, regarding opacity of the healed TM area, heparin affected the TM in a dose-dependent manner. The TMs that had been subjected to the highest concentration of heparin were the most transparent and showed the least sclerosis. When compared for thickness, the TMs treated with the higher concentration of heparin were considerably thinner than those treated with the lower concentration. The sterile water-treated controls were all thicker than the heparin-treated TMs. It is inferred that glycosaminoglycan heparin improves the quality of the healed area of TM perforations.

Lightning injury of the tympanic membrane

A number of cases of otologic injuries by lighting strikes have been described in the otolaryngological literature. The mechanism of these injuries remains uncertain. We report 3 cases of lightning injury that presented to us. Analysis of these cases suggests that the mechanism of injury is direct conduction of electricity from the scalp to the soft tissues of the external auditory canal to the tympanic membrane. The conduits of the electrical surge are the subcutaneous blood vessels, smaller vessels being damaged more than larger vessels. Since the tympanic membrane central vessels are smaller than the canal vessels, the central area of the tympanic membrane would be most vulnerable, and this is seen clinically. A review of the literature supports this proposed mechanism of injury.

Prospective study of resident-performed stapedectomy

Because of the diminishing number of patients diagnosed with otosclerosis, the adequacy of residency training in stapedectomy techniques remains controversial. A prospective study, conducted from 1986 to 1991, assessed whether or not surgical outcome obtained by residents, under close supervision by otologic faculty, could be improved using a single stapedectomy technique. Comparison of pre- and postoperative hearing results (pure-tone averages of 500, 1000, and 2000 Hz) from 49 cases revealed closure of the air-bone gap to within 10 dB in 68 percent of procedures. Complications included failure to improve the conductive hearing loss, tympanic membrane perforations, transient facial nerve weakness, subluxation of the incus, and adhesions. The failure to improve the success rate in resident-performed procedures relates to the individual learning curve and the limited number of training cases.

[Clinical study on perforation of the tympanic membrane and discussion based on experimentally induced tympanic rupture]

Traumatic perforation of the tympanic membrane (TM) was clinically studied by analyzing photographs of 231 ears treated in the Department of Otolaryngology of Tokyo Women's Medical College from May 1983 to December 1991. The dynamic features of TM and the mechanism of perforation are discussed.

RESULTS AND DISCUSSION

1) Direct and indirect injuries of the TM through the external auditory canals were observed in 101 and 130 ears, respectively. One hundred and twenty-seven injured ears were seen in males and 104 in females. Subjects ages ranged from 1 to 64 years. One hundred and thirty ears were on the left side and 101 on the right. 2) Approximately 80% of the perforated regions were observed in the antero-inferior or postero-inferior quadrant. "Triangular-type" perforation was predominant among direct injuries and "slit type" among indirect injuries. 3) Approximately 80% of the cases had a TM defect area smaller than 20%. 4) One hundred and twenty of 127 ears which were treated within 7 days after injury were healed by conservative treatment. One hundred and four ears among these 120 ears healed spontaneously. The average healing period for these 104 ears was 25 days. 5) It was suggested that the age of patients and the defect area of TM were factors that delayed healing. 6) The minimum breakage stress of human normal TM (the right angle to the radial fibers of TM) was 13.7 gf/mm2. 7) It was presumed that the strain stress and shear stress of TM contributed to traumatic TM perforation in indirect injuries.

Direct application of basic fibroblast growth factor improves tympanic membrane perforation healing

Topical application of basic fibroblast growth factor (b-FGF) on tympanic membrane (TM) perforations was studied in guinea pigs. One-millimeter simple round TM perforations or 2-mm TM perforations with medially flapped borders were performed. Either b-FGF or placebo was instilled in each ear on the day of surgery and daily thereafter. Treatment was applied either directly to the perforation or to a Gelfoam pledget over the defect. When no scaffolding material was interposed, b-FGF induced a faster healing response characterized by a hyperplastic but linear subepidermal connective tissue reaction compared to the control. When Gelfoam was interposed as a scaffold, a voluminous scar protruding into the middle ear cavity and involving the ossicles was observed in both b-FGF and control animals. Gelfoam-induced scars did not decrease after long-term observation, therefore discouraging its use.

Tympanic membrane ossification

Ossification of the tympanic membrane after myringoplasty is recorded for the first time. Myringoplasty was performed for closure of a perforation which followed the surgical treatment of otitis media with effusion and had included the insertion of a long-term T-tube.

Animal model for persistent tympanic membrane perforations

Topically applied hydrocortisone was used to develop an animal model for persistent tympanic membrane (TM) perforations. Hydrocortisone suspension was applied on the margins of TM perforations of standardized size in rats once daily for 10 days. The healing patterns of the TMs were mapped weekly and, when the perforations were about to close, daily. After 50 days, all hydrocortisone-treated perforations were open, whereas the controls closed within 9 to 12 days. At 3 months, when one third of the perforations still were open, the TMs were studied by otomicroscopy and light microscopy. All TMs were thickened and covered by keratin and wax. The thickened epidermal layer at the border of the TM perforations that remained open also draped the surface of the perforation facing the middle ear cavity. The thickened connective tissue layer contained abundant fibroblasts with their axes of length oriented at random. Both application of 1.4% hyaluronan and wounding of the perforation border enhanced the healing rate of the hydrocortisone-induced chronic TM perforation.

Clinical characteristics and hearing recovery in perilymphatic fistulas of different etiologies

Clinical features and hearing recovery were compared between three types of perilymphatic fistula groups; surgically confirmed (PLF-conf, n = 16), suspected (PLF-susp, n = 24) and traumatic (trauma-PLF, n = 11). Initial average hearing level was best in the PLF-susp group (50.9 dBHL), followed by the trauma-PLF (55.7 dBHL) and PLF-conf (59.7 dBHL) groups, though the difference was not significant (ANOVA, p > 0.05). Of 51 patients, 27 cases were operated on and fistula was confirmed in 19 ears (70.4%). Conservative treatment, including bed rest and medication, was given to all patients. After the treatment, meaningful hearing recovery was obtained only at 1 kHz in the PLF-conf group (paired t-test, p < 0.05). However, significant recovery was seen at all frequency ranges (0.125-8 kHz) in the PLF-susp group (average, 16.8 dB; p < 0.01), while hearing improvement was intermediate for the trauma-PLF group. The initial hearing level and the period until the start of treatment strongly correlated with the final hearing level. Although 27 patients (47%) complained of dizziness, the prognosis for vertigo is excellent as noted by other authors. It was concluded that if conservative treatment is started early for PLF patients with mild hearing loss, hearing recovery can be ensured.

Facial nerve paralysis from slag injury to the ear

Transtympanic facial nerve paralysis resulting from a penetrating injury through the external auditory canal is a rare occurrence. The common mechanism of paralysis is direct fracture or penetration of the fallopian canal. Slag injuries of the ear caused by hot sparks or molten metal are well known to otolaryngologists because they often result in chronic tympanic membrane perforations and chronic otorrhea. We have encountered two unusual cases of transtympanic slag injury to the ear that resulted in facial nerve injury. In one patient, a significant inner ear injury also occurred. A pathophysiologic mechanism of thermal injury is proposed, and the use of ear protection in welders is discussed.

Histological study of the healing of traumatic tympanic membrane perforation after basic fibroblast growth factor application

Basic fibroblast growth factor (bFGF) can stimulate the proliferation and differentiation of keratinocytes, fibroblasts, and endothelial cells. These cells are involved during the healing of tympanic membrane (TM) perforations. Light and electron microscopy examinations were used to study the histology of TM healing after application of 400 ng of bFGF on the perforation. The progress of healing is accelerated, but the basic healing process is unchanged, i.e., epithelial proliferation first closes the perforation and is then followed by connective tissue growth. There is more connective tissue in the TM receiving bFGF, and extracellular fibers are better oriented. No significant increase of neoangiogenesis was detected in the treated TM. In the nonperforated area of treated TM, an extensive hyperplasia of the submucosal connective tissue is observed. These results demonstrate that bFGF can produce a TM scar containing more connective tissue, which may be of benefit in the prevention of atrophic healed TM.

Barotrauma in Boeing 737 cabin crew

Several aircrew members of a Boeing 737 aircraft were referred to our department because they suffered from a barotrauma. The fast rate of pressure change during the descent of a Boeing 737 aircraft, as compared to the Boeing 747, DC-10 and Airbus 310 aircrafts, is most likely the cause of the development of the barotraumata.

Asymptomatic osteomas of the middle ear

Osteomas of the middle ear are extremely rare lesions. Of the nine cases reported, eight presented with conductive hearing loss. We recently treated two patients whose osteomas, of the promontory and of the posteroinferior tympanic wall, were asymptomatic. We suggest that middle ear osteomas need not be removed when they do not impinge on the sound conduction system.

Experimental pressure induced rupture of the tympanic membrane in man

The size of the overpressure in the ear canal which causes rupture of the tympanic membrane (TM) in man (rupture pressure, RP) was determined in 90 subjects 7-112 h post mortem in connection with the autopsy. The equipment allowed an overpressure in the ear canal to be applied either gradually or suddenly. In 144 normal TMs it was demonstrated that the tensile strength of the TM increases post mortem. Corrected to the time 0 post mortem, RP of normal TMs ranged 0.5-2.1 kp/cm2, median 1.2 kp/cm2. It was found to be correlated to the age of the patient, i.e. RP decreased with increasing age. No correlation was found between RP and the application speed of the overpressure. Ninety-nine percent of the ruptures were localized to the pars tensa (63% to the anterior part of this structure) and typically had the shape of a minor tear. The RP of 23 TMs with atrophic scars was significantly lower, 0.3-0.8 kp/cm2, and the rupture typically had the shape of a larger defect. The results of this study indicate large intersubject variability of the tensile strength of the human TM. Some individuals are at increased risk of TM rupture at minor overpressures in the ear canal (e.g. during certain watersports, such as diving) which may carry medicolegal implications.

Middle ear barotrauma associated with hyperbaric oxygenation treatment

We investigated the signs and symptoms of middle ear barotrauma in 67 patients with hyperbaric oxygenation treatment as well as the influence of predisposing factors. Ear damage was classified into 5 grades on the basis of objective findings at otoscopic examination. The incidence of middle ear barotrauma assessed by objective criteria was 68.7%, and showed little variation with age or primary disease. On the other hand, the incidence assessed by subjective symptoms was lower than the objectively-based incidence in aged patients, those with severe neurological diseases, and those who had difficulties speaking. Patients with a trauma grade of 2 or more complained of severe symptoms and were appropriate candidates for treatment. It is considered that otoscopic examination should be performed in patients who undergo hyperbaric oxygenation treatment and that prior management of nasal and paranasal diseases is beneficial in the prevention and treatment of middle ear barotrauma.

T-tubes: a retrospective review of 1274 insertions over a 4-year period

1274 T-tubes were inserted for persistent otitis media with effusion in 661 patients over a 4-year period. The peak ages for insertion were between 4 and 7 years, and by 11 years the condition is uncommon. If a tube has not extruded spontaneously after 30 months it becomes increasingly less likely to do so. Complications were persistent perforations (32.6%), tympanosclerosis (23.6%), repeated otorrhoea or tympanic membrane granulations (21%), and impacted wax (10.9%). Forty-eight percent of patients experienced one or more complication in the study period, and the complication rate increased dramatically in patients whose tubes had remained in situ for longer than 36 months. After this time surgical removal is recommended.

Spontaneous healing of traumatic tympanic membrane perforations in man: a century of experience

Widespread controversy exists concerning the treatment of traumatic tympanic membrane perforations. To elucidate the issue, a reference value for the rate of spontaneous tympanic membrane closure in man, to which the healing rates following different techniques of early surgical repair should be compared, was established on the basis of a review of more than 500 texts covering a century's literature on the traumatically perforated tympanic membrane. The spontaneous healing rate appeared to be close to 80 (78.7 per cent) in 760 evaluable cases of traumatic tympanic membrane perforations of all sorts diagnosed within 14 days post injury. A relative, causal-related variation of spontaneous healing could be demonstrated, and a pathogenetic classification of direct traumatic tympanic membrane perforations into ruptures induced by air-pressure changes, heat or corrosives, solids, and water pressures, is of proved clinical value and may have medico-legal validity. There is an obvious need for clinically controlled studies on the spontaneous healing of all kinds of traumatic perforations of the tympanic membrane in humans, and important elements in the design of future studies are advocated.