Blast injury of the ear: an overview and guide to management

Otologic Outcomes After Blast Injury: The Brussels Bombing Experience

OBJECTIVE

After the suicide bombings in Brussels on March 22, 2016, many victims consulted our emergency department with otologic symptoms. The aim of this study was to report the otologic morbidity and outcome after acute acoustic trauma in these patients.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Patients reporting subjective hearing loss, tinnitus, feeling of pressure in the ear, vertigo or hyperacusis after witnessing these bombings were included.

INTERVENTION

All included patients were treated with systemic corticosteroid therapy, concurrent hyperbaric oxygen therapy (HBOT) was advised to each and every included patient.

MAIN OUTCOME MEASURES

Participants underwent a routine otologic work-up including otoscopy, liminal audiometry, and subjective outcome measures related to tinnitus at baseline and at follow-up. Primary outcome was to describe the otologic morbidity after acute acoustic trauma (AAT). Secondary outcome was to evaluate the recovery of hearing loss, subjective symptoms, and tympanic membrane perforations.

RESULTS

Fifty-six patients were included in our population with an average age of 27 ± 13 years, and 46% women/54% men. Thirty-two patients reported subjective hearing loss, 45 reported tinnitus, 45 reported a feeling of pressure in the ear, 2 patients experienced vertigo, and 18 patients reported hyperacusis. Otoscopic examination revealed three tympanic membrane perforation (TMP). Sensorineural hearing loss (SNHL) was observed in 41% (n = 23) and mixed hearing loss in 3.6% (n = 2). No conductive hearing loss (CHL) was observed. Follow-up was obtained in 76.8%, with the last follow-up available at 47 ± 74 days. Two perforations closed spontaneously, while one persistent perforation was successfully reconstructed with complete air-bone gap closure. There was a significant improvement in subjective symptoms. SNHL improvement was observed in 52.6% (10/19), mixed hearing loss improved in both patients. Improvement in hearing thresholds was seen in patients treated with steroids and in those treated with steroids and HBOT, there was no significant difference in the degree of improvement between these two groups.

CONCLUSIONS

Blast-related otologic injuries have a significant impact on morbidity. Comprehensive otologic evaluation and state-of-the-art treatment may lead to a significant improvement in symptoms and hearing loss.

Aural Blast Injury/Acoustic Trauma and Hearing Loss

Hearing is a critical sense to military performance. The ability to detect, identify, and localize sounds, the ability to maintain spatial awareness on the battlefield and the awareness to control one's own noise production can be vital to troop's stealth, survivability, and lethality. Hazardous noise is an environmental public health threat encountered in training at war, and in many off-duty activities. The risk to hearing and the resultant damage from any of these hazardous exposures is generally invisible, insidious and cumulative. Regardless of the source of injury, hearing loss degrades the sensor that integrates Service Members with their environment, provides for unity of effort, and ensures command and control.Acoustic trauma-induced hear loss and tinnitus are the two most prevalent disabilities in veterans, with over 765,000 cases in the Gulf War era alone. To counter this threat, it is necessary to push for early identification and early intervention through a trusted surveillance system. Success will require advocacy, education, and encouragement of self-reporting for evaluation following symptomatic noise exposures. This Clinical Practice Guideline (CPG) is a step to ensure the hearing health, readiness, protection, and care of Service Members. This will in turn optimize troop performance and minimize injury risk and mishap.

Mechanisms and treatment of blast induced hearing loss

The main objective of this study is to provide an overview of the basic mechanisms of blast induced hearing loss and review pharmacological treatments or interventions that can reduce or inhibit blast induced hearing loss. The mechanisms of blast induced hearing loss have been studied in experimental animal models mimicking features of damage or injury seen in human. Blast induced hearing loss is characterized by perforation and rupture of the tympanic membrane, ossicular damage, basilar membrane damage, inner and outer hair cell loss, rupture of round window, changes in chemical components of cochlear fluid, vasospasm, ischemia, oxidative stress, excitotoxicity, hematoma, and hemorrhage in both animals and humans. These histopathological consequences of blast exposure can induce hearing loss, tinnitus, dizziness, and headache. The pharmacological approaches to block or inhibit some of the auditory pathological consequences caused by blast exposure have been developed with antioxidant drugs such as 2,4-disulfonyl α-phenyl tertiary butyl nitrone (HXY-059, now called HPN-07) and N-acetylcysteine (NAC). A combination of antioxidant drugs (HPN-07 and NAC) was administered to reduce blast induced cochlear damage and hearing loss. The combination of the antioxidant drugs can prevent or treat blast induced hearing loss by reducing damage to the mechanical and neural component of the auditory system. Although information of the underlying mechanisms and treatment of blast induced hearing loss are provided, further and deep research should be achieved due to the limited and controversial knowledge.

Prehospital care algorithm for blast injuries due to bombing incidents

Terrorist bombings continue to remain a risk for local jurisdictions, and retrospective data from the United States show that bombings occur in residential and business areas due to interpersonal violence without political motives. In the event of a mass-casualty bombing incident, prehospital care providers will have the responsibility for identifying and managing blast injuries unique to bombing victims. In a large-scale event, emergency medical services personnel should be required to provide prolonged medical care in the prehospital setting, and they will be able to deliver improved care with a better understanding of blast injuries and a concise algorithm for managing them. Blast injuries are categorized as primary, secondary, tertiary, and quaternary, and these injuries are related to the mechanism of injury from the blast event. After an initial evaluation, the emergency healthcare provider should consider following a universal algorithm to identify and treat blast injuries within these categories to prevent further morbidity or mortality in the prehospital setting.

Otologic considerations of blast injury

The ear by design is exquisitely sensitive to barotrauma. As a result, it is typically the first organ affected in primary blast injury. The most common symptoms encountered include hearing loss, ringing, and drainage. In severe cases, the highest priority is appropriately directed toward diagnosis and treatment of life-threatening injuries; however, injury to the ear is missed frequently. With simple screening procedures, limited management, and appropriate otolaryngologic referral, acute and long-term morbidity can be averted for both critical and noncritical patients. The article provides an overview of blast mechanics and pathophysiology. It details various blast-related injuries to the external, middle, and inner ear. Standard of care assessment and management strategies are presented for acute and late otologic sequelae of the blast-injured patient.

[Blast lung injuries]

In armed conflicts and during terrorist attacks, explosive devices are a major cause of mortality. The lung is one of the organs most sensitive to blasts. Thus, today it is important that every GP at least knows the basics and practices regarding treatment of blast victims. We suggest, following a review of the explosions and an assessment of the current threats, detailing the lung injuries brought about by the explosions and the main treatments currently recommended.

Ritonavir and disulfiram have potential to inhibit caspase-1 mediated inflammation and reduce neurological sequelae after minor blast exposure

Caspase-1 triggers cytokine release following acceleration-induced concussive head injury. Minor blast injury in which no physical tissue injury occurs, results in the release of cytokines in a similar fashion. Ritonavir, a generically available protease inhibitor with a benign short-term side-effect profile, has been shown to inhibit expression of caspase-1. We review the relevant literature and propose that ritonavir may be of benefit in reducing adverse neuropsychiatric outcomes and hastening recovery following mild blast injury. Further research in animal models of blast injury followed by clinical studies would determine whether this therapy is effective.

[Characteristics of sensorineural hearing loss secondary to inner ear acoustic trauma]

INTRODUCTION

Cochlear damage secondary to exposure to acoustic trauma is the consequence of the acoustic energy effects on the hearing cells in Korti's organ.

OBJECTIVE

The objective was to assess the correlation between the degree of sensorineural hearing loss and the type of audiogram registered in acoustic trauma exposed patients.

METHOD

We analysed 262 audiograms of patients exposed to acoustic trauma in correlation to 146 audiograms of patients with cochlear damage and hearing loss not related to acoustic trauma. "A" group consisted of acoustic trauma cases, while "B" group incorporated cases with hearing loss secondary to cochlear ischaemia or degeneration. All audiograms were subdivided with regard to the mean hearing loss into three groups: mild (21-40 dB HL), moderate (41-60 dB HL) and severe (over 60 dB HL) hearing loss. Based on audiogram configuration five types of audiogram were defined: type 1 flat; type 2 hearing threshold slope at 2 kHz, type 3 hearing threshold slope at 4 kHz; type 4 hearing threshold notch at 2 kHz; type 5 notch at 4 kHz.

RESULTS

Mild hearing loss was recorded in 163 (62.2%) ears in the acoustic trauma group, while in 78 (29.8%) ears we established moderate hearing loss with the maximum threshold shift at frequencies ranging from 4 kHz to 8 kHz. The least frequent was profound hearing loss, obtained in 21 (8%) audiograms in the acoustic trauma group. Characteristic audiogram configurations in the acoustic trauma patient group were: type 1 (N = 66; 25.2%), type 2 (N = 71; 27.1%), and type 3 (N = 68; 25.9%). Audiogram configurations were significanly different in the acoustic trauma group in comparison to the cochlear ischaemia group of patients (p = 0.0005).

CONCLUSION

Cochlear damage concomitant to acoustic trauma could be assessed by the audiogram configuration. Preserved hearing acuity at low and mild frequency range indicates the limited damage to the hearing cells in Korti's organ in the apical cochlear turn.

Primary blast injury: update on diagnosis and treatment

BACKGROUND

: Injuries from combat and terrorist explosions are increasing worldwide. As such, physicians can expect to treat more patients with complex and unique patterns of injury produced not only by fragments and blunt trauma, but also by high-pressure air expanding from the detonation center.

DISCUSSION

: Tissue damage from the blast wave or primary blast injury can be an important cause of occult trauma to the ocular, aural, pulmonary, cardiovascular, musculoskeletal, and neurologic systems. Awareness of the extensive corporal effects of the blast wave is an essential prerequisite to diagnosis.

SUMMARY

: This article focuses on the incidence, risk factors, diagnosis, management, and screening for primary blast injury.

Tympanic membrane perforation and hearing loss from blast overpressure in Operation Enduring Freedom and Operation Iraqi Freedom wounded

BACKGROUND

Tympanic membrane perforation is the most common primary blast injury in the current conflicts and occurs in approximately one tenth of service members wounded by combat explosions. We wanted to determine the severity of perforation and its effect on hearing and combat readiness.

METHODS

This analysis is a retrospective study of US service members injured in combat explosions in Afghanistan or Iraq and treated at our institution between March 2003 and July 2006. Data captured included location and grade of perforation, symptoms, healing rates, audiogram results, need for hearing aids, and loss of eligibility for military service.

RESULTS

Of 436 explosion-wounded patients admitted to our facility, 65 (15%) patients had tympanic membrane perforation diagnosed by the otolaryngology service. A total of 97 tympanic membrane perforations occurred among 65 patients. The average surface area involved was 41% +/- 32% (right) and 35% +/- 34% (left). More than one third of perforations were grade 4. The most common locations were central and anterior-inferior. Most (83%) patients reported symptoms, most commonly diminished hearing (77%) and tinnitus (50%). Outcome data were available for 77% of perforations. Spontaneous healing occurred in 48%. The remainder (52%) had surgical intervention. The most common audiogram abnormality was mild high frequency hearing loss. Ultimately, three patients (5%) required hearing aids and one discharge from military service.

CONCLUSIONS

Tympanic membrane perforation occurs in 16% of explosion-injured patients. Most patients are symptomatic and many have large perforations requiring operative intervention. Long-term hearing loss is uncommon but does impact ability to continue military service.

Facing the new threats of terrorism: radiologists' perspectives based on experience in Israel

On September 11, 2001, the world changed. The vicious giant of terrorism that was dormant until that date had arisen. After the horrific mass-casualty terror attack on the United States, any and all forms of assault seem possible. Owing to the complexity of injuries encountered in terror attack victims, fast and accurate imaging plays an essential role in triage and identification of abnormalities associated with injuries. The radiologist becomes a crucial part of the first-line team of doctors treating these patients. Knowledge that the best available treatment is given to terror attack victims can enhance the strength and endurance of society against terror. On the basis of the authors' experience with terror events in Israel, the steps involved in imaging of terror attack patients include conventional radiography, focused abdominal sonography in trauma, computed tomography, and angiography, with the judicious use of supplemental imaging.

Otorrinolaringología

The terrorist attack on 11 March caused a high percentage of patients with ear injuries. Shock waves provoke alterations to the external ear as well as to the middle and inner ear. The most frequent lesion is tympanic membrane perforation. Initial evaluation with otoscopy, acoumetry, tonal audiometry and vestibular examination was performed and was repeated after 2 and 3 months. In most patients there was a correlation between the grade of middle ear lesion and auditory damage. In most patients with tympanic rupture, the perforation was total or subtotal. Spontaneous closure can occur in some patients but is usually related to the size of the initial lesion. Thus in tympanic perforations of more than 50%, spontaneous closure is unlikely.