**4. Discussion**

Trauma to the ear can be classified on the basis onf the anatomical location or the type of injury. This could be a simple blunt trauma to the pinna; laceration of the pinna, avulsion of part or the whole of the pinna; tympanic membrane perforation; dislocation of the ossicles; longitudinal and transverse fractures of the petrous temporal bone with

**Frequency Female** 

**Predisposition Number &** 

**Explosion** 03

Table 2. Predisposition and sex of patients.

Table 3. Aetiological profile of TM perforations.

Table 4. Sources of Slaps.

**4. Discussion** 

**Security Agent** 4 (17.4) **Assault from Fight** 7 (30.5) **Spouse** 2 (8.7) **Armed Robbery** 3 (13.0) **Senior student/cultists** 4 (17.4) **Sibling** 3 (13.0)

**Male** 

**Slap** 15 08 **Instrumentation** 04 03 **Self during ear cleaning** 05 02 **RTI** 09 01 **Foreign body** 10 03

**Fall** 01 **Total** 46 18

**Slaps** 23 (35.9%) **Instrumentations** 7 (10.9%) **Self Ear cleaning** 7 (10.9%) **Road Traffic Injury** 15 (23.5%) **Foreign body** 08 (12.5%) **Explosions** 3 (4.7%) **Falls** 1 (1.6%)

**Aetiology Number &Frequency (%)** 

**Sources of slap Number & Frequency (%)** 

Trauma to the ear can be classified on the basis onf the anatomical location or the type of injury. This could be a simple blunt trauma to the pinna; laceration of the pinna, avulsion of part or the whole of the pinna; tympanic membrane perforation; dislocation of the ossicles; longitudinal and transverse fractures of the petrous temporal bone with associated loss of inner ear and facial nerve function (Ologe FE 2002, Toner JG & Kerr AG 1997, Okafor BC 1983, Ijaduola GTA 1986, Bhattia PL 1987, Ladapo AA 1979, Ijaduola GTA and Okeowo PA 1986). Previous studies have shown that trauma to the tympanic membrane and the middle ear can be caused by overpressure (slap, fight, assault from security agents and road traffic injury (RTI)), thermal or caustic burns, blunt or penetrating injuries such as instruments and barotraumas (Mitchell K. S 2003, da Lilly-Tariah OB and Somefun OA 2007). Overpressure is by far the most common mechanism of trauma to the tympanic membrane (Mitchell K. S 2003) in our environment. Traumatic perforation of the tympanic membrane may be caused by direct impact of fluids and direct pressure from outside.

The tympanic membrane (TM) is an important component of sound conduction as its vibratory characteristic is necessary for sound transmission in human beings (Richard R. G and Mark R.G 2003)

Traumatic tympanic membrane perforation findings from our study are similar to findings elsewhere from the world (Ologe FE 2002, Mitchell K. S 2003, da Lilly-Tariah OB and Somefun OA 2007). Male to female ratio was found to be 2.5:1 with high predominance among males (72%). This is expected, as trauma is more common in this group of patients similar to other reported series (Ologe FE 2002, da Lilly-Tariah OB and Somefun OA 2007, Richard R. G and Mark R.G 2003). Our study of injury site indicated that the left ear is at a higher risk than the right ear in the ratio of 1.0:1.3 right to left which could be associated with the fact that most assailants were right handed, Thus it is likely that most of the acts of trauma such as slap occurred with the assailant and victims were facing each other making the left ear to be predominantly affected compared to the right side. Some of the causes of overpressure include slap injuries and blast injuries. Slap injuries are extremely common and can be result of either a hand or water slap and these injuries usually result in a triangular or linear tear of the TM (Mitchell K. S 2003). These slap injuries could be a product of fight or armed robbery attack. However, in our study it was found to be more common among the youth. In more than 50%of cases reviewed and those in the adult these cases were due to attack by the armed robbers or security agents. This was the highest cause of traumatic tympanic membrane perforation in our study as compared to a similar study in other regions of Nigeria where fight with spouse was the commonest aetiology recorded (da Lilly-Tariah OB and Somefun OA 2007). In contrast this type of injury made the least contribution in our study.

Slaps were the commonest type of violence seen between individuals, mostly between security agents and the offender followed by those among students. However, another study found tympanic membrane perforation resulting from slap from marital conflict between wife and husband (Mitchell K. S 2003). There is a need to educate the students and security agents on other punitive measure as there is predisposition to conductive hearing loss or an imminent chronic suppurative otitis media if not properly managed. Slap was commoner among males than in females similar to another study (Mitchell K. S 2003). Trauma to the temporal bone with fracture and leakage of cerebrospinal fluid into the middle ear causing conductive hearing losses was second common in this study and this was found to be secondary to road traffic injury. The management protocol for skull base fracture with TM perforation/CSF leakage does not require any intervention based on

Conductive Hearing Loss Due to Trauma 169

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Otolaryngologist perspective to avoid contamination with an ascending infection. This was also found to be higher among male subjects compared to the females, perhaps associated with the role of males in African society as the bread winners, working outside home and thus are at a higher risk of various type of traffic injuries compared to women who predominantly stay at home. Attempt at removing foreign body, ear cleaning with variety of objects including cotton bud and wax removal in an unskilled manner either by the parents or the primary care physician with TM perforation was an important cause of hearing loss found mostly among children as previously reported (Ologe FE 2002, Toner JG & Kerr AG 1997, Ladapo AA 1979, Ijaduola GTA and Okeowo PA 1986). There is a need for a primary care physician to provide patients with appropriate referral. Explosion is not a common phenomenon in our environment as the violence rate is still at a low level. Fall with perforation of tympanic membrane is an uncommon occurrence which has never been reported but was observed in a child, however the mechanism could not be explained.

Traumatic perforations often occur in healthy members of the community with generally an excellent prognosis (Toner JG & Kerr AG 1997, Ijaduola GTA 1986). Healing with formation of neomembrane was observed only in five patients (7.8%) and it is among the under five's this is not surprising as they are still growing.

#### **5. Conclusion**

Traumatic perforation of the tympanic membrane is still common in our environment. It affects all age groups, with more males affected than females. Slaps and RTI are the commonest aetiologies seen. The left ear is affected more than the right and sudden hearing loss is the most common presentation. There is a need to educate the students and security agents on alternative punitive measures and to discourage the act of unskilled removal of foreign body from the ear. Early identification, evaluation and referral of patients by primary care physician who see these patients will reduce the attendant morbidity.

#### **6. References**


Otolaryngologist perspective to avoid contamination with an ascending infection. This was also found to be higher among male subjects compared to the females, perhaps associated with the role of males in African society as the bread winners, working outside home and thus are at a higher risk of various type of traffic injuries compared to women who predominantly stay at home. Attempt at removing foreign body, ear cleaning with variety of objects including cotton bud and wax removal in an unskilled manner either by the parents or the primary care physician with TM perforation was an important cause of hearing loss found mostly among children as previously reported (Ologe FE 2002, Toner JG & Kerr AG 1997, Ladapo AA 1979, Ijaduola GTA and Okeowo PA 1986). There is a need for a primary care physician to provide patients with appropriate referral. Explosion is not a common phenomenon in our environment as the violence rate is still at a low level. Fall with perforation of tympanic membrane is an uncommon occurrence which has never been reported but was observed in a child, however the mechanism could not be

Traumatic perforations often occur in healthy members of the community with generally an excellent prognosis (Toner JG & Kerr AG 1997, Ijaduola GTA 1986). Healing with formation of neomembrane was observed only in five patients (7.8%) and it is among the under five's

Traumatic perforation of the tympanic membrane is still common in our environment. It affects all age groups, with more males affected than females. Slaps and RTI are the commonest aetiologies seen. The left ear is affected more than the right and sudden hearing loss is the most common presentation. There is a need to educate the students and security agents on alternative punitive measures and to discourage the act of unskilled removal of foreign body from the ear. Early identification, evaluation and referral of patients by primary care physician who see these patients will reduce the attendant

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explained.

**5. Conclusion** 

morbidity.

**6. References** 

this is not surprising as they are still growing.

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**9** 

*1Australia 2China* 

**Occupational Chemical-Induced Hearing Loss** 

Exposure to chemicals in the workplace can lead to occupational chemical-induced hearing loss, as many chemicals have been internationally recognised as hazardous to hearing. A number of studies have demonstrated that, similar to noise, some chemicals not only affect the sensory organ of the auditory system (the cochlea) but also lead to adverse effects in central auditory structures. Morata and Lemasters (1995) suggested that the adverse auditory effects of chemicals such as solvents are due to a combination of oto-and neurotoxicity. Oto-toxicity induces outer hair cell (OHC) dysfunction in the cochlea (similar to the effects of noise), whereas neuro-toxicity induces central auditory dysfunction. The main audiological sign of oto-toxicity is poorer hearing thresholds than expected relative to age. Audiological signs of neuro-toxicity may or may not include poorer hearing thresholds, in addition to difficulties discriminating sounds, such as speech, particularly in adverse

The aim of this review is to provide an in-depth discussion of occupational chemicalinduced hearing loss, taking into consideration ototoxic agents such as solvents, pesticides and metals, and their interaction with noise. Contemporary findings from research conducted in animals and humans are included here. Also, research findings from the authors with regard to the effect of exposure to mixtures of solvents on the peripheral and central auditory system will be addressed. Finally, in the section on international legislation of occupational chemical-induced hearing loss, a review of current legislation in a number

A solvent is a liquid used to dissolve other substances. Most solvents are colourless liquids at room temperature that volatise easily and have strong odours. Solvents are most commonly inhaled in their volatised form and absorbed through the respiratory tract. Organic solvents are widely used around the world and many different industrial processes require their use. Table 1 summarises the main organic solvents and their common

**1. Introduction** 

listening conditions.

of countries is presented.

**2.1 Overview of solvents** 

industrial uses.

**2. Solvent-induced hearing loss** 

Adrian Fuente1 and Bradley McPherson2

*1The University of Queensland 2The University of Hong Kong* 

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