**1. Introduction**

Hearing loss is a common problem encountered in ENT practice. Recognition of hearing loss as a problem by the patient usually occurs when speech frequencies are affected or when there is a sudden hearing loss. Hearing loss following head trauma or head injury is a major medical problem in adults (Bergemalm P-O&Borg.E. 2001) as well as children (Hough JVD &Stuart WD, 1968). The loss may go unnoticed when the speech frequencies are not affected. Sensorineural hearing loss at high frequencies is a frequent finding associated with head injuries (H.Alexander Arts). Hearing impairment can be due to central or peripheral causes, middle ear or cochlea being the most common site of peripheral injury. The most pronounced injury is fracture of temporal bone (Dahiya.R &Keller J.D, 1999). In both clinical and animal experimental studies it has been shown that there are various sites of pathology ranging from hair cell damage and degeneration of the organ of corti, ischemia of the 8th nerve to damage of central auditory pathways (due to compromise of blood supply to the inner ear ) either partly or totally. In most cases hearing impairment dissipates during subsequent post traumatic period, but some times it may persist or progress.

The causes of progression of hearing loss are not well known. Several explanations have been proposed such as development of perilymphatic fistula, secondary degenerative changes in cochlea following inner ear concussion possibly due to consequences of preexisting autoimmune disease (or trauma itself may initiate such a reaction towards specific inner ear proteins). Progression of hearing loss can be attributed to the synergistic effects between trauma, noise exposure, medication and meningitis.

In developing countries roads are used not only by modern cars and buses, along with locally developed vehicles for public transport (three-wheeled scooter taxis, auto rickshaw's), scooters and motorcycles, bicycles, but also by rickshaws, and animal or human drawn carts that has resulted in disproportionate increase in road traffic accidents compared to developed countries. Minor head injuries (WHO 2004) constitute a major portion of all accidents. Evaluation of these patients revealed presence of hearing loss in the high frequency range. Hence auditory assessment is needed in this group of patients.

Evaluation of hearing loss in patients who sustain minor head injury has not been done in the Indian subcontinent. Therefore, this prospective study was done to evaluate the incidence of hearing loss and estimate its progression or regression by serial assessment over a period of six months

Hearing Loss in Minor Head Injury 137

injuries and deaths through bi-weekly home visits to all households in 9 villages for a year. This study showed that the ratio between critical, serious and minor injuries was 1:29:69.

A mild head injury can be defined as an injury caused by blunt trauma and/or sudden acceleration /deceleration which produces a period of unconsciousness for 20 minutes or less, a Glasgow coma scale score of 13-15, no focal neurological deficit, no intracranial complications and computed tomographic findings limited to a skull fracture without evidence of contusion or hematoma.Despite the dissemination of information that is available on diagnostic criteria,

Estimating the duration of unconsciousness is difficult when witnesses are not available, second if the patient is intoxicated at the time of hospital admission it can obscure the

Deafness due to head injury is known since ancient times, the earliest account of which is the Edwin Smith papyrus, (Marc stiefel, 2006) the world's earliest known medical document, written around 1600 BC, but thought to be based on material from as early as 3000 BC. It is a textbook on trauma surgery, and describes anatomical observations physical examination, diagnosis, treatment, and prognosis of numerous injuries in exquisite detail. The symptoms and signs of head injury were given in considerable detail. It was noted that brain injuries were associated with changes in the function of other parts of the body. Feeble pulse and fever are associated with grievous injuries and deafness as well as aphasia are recognized in

Sushrutha who is known as "Father of Surgery" in India, even though he does not attach significance to the brain, however, considers head as the centre of all special senses and describes certain cranial nerves connected with specific sensory functions. He described two nerves lower down the back of the ear (vidhura), which, if cut, produce deafness; a pair of nerves (phana) situated inside the two nostrils, which if cut, cause anosmia. A pair of nerves below the outer end of the eye-brow, near the external corner of the eyeball (apanga) which

Alexander and Scholl (Alexander AF and Scholl) as early as 1938 reported a 31% incidence of hearing loss in patients with head injury. In 1939 Grove (Grove W.E) reported an incidence of 32.6% of sensorineural hearing loss and suggested that bleeding in the inner ear was the cause whereas Uffenorde (Uffenorde W, 1924) stated that stretching of the fibers of the cochlear nerve in the internal auditory canal bought on the hearing loss after head injury. Similar results were reported by Gurdijan,( Gurdijan ES 1933) Fradis and Podoshin (Podoshin .L&,Fradis.M,1975) and M R Abd al Hady ( M.R.Abd AL-HADY et al,1990). Griffiths ( M.V.Griffiths )in 1979 reported an incidence of 56% of sensorineural deafness in cases of mild head injury . He stated that there may be difference in outcome depending on the type of violence. A blow to the head with a soft object seems to cause less damage to the hearing system than a blow to the head with a hard object with the same power at impact.

The greater hearing loss according to him is due to an acoustic component.

controversies still exist in defining mild head injury and collecting patients.

(Varghese .M .Mohan.D 2003).

**2.1 Definition of a mild head injury** 

assessment of severity of head injury.

**3. Hearing loss in head injury** 

fractures of the temporal region.

if cut, cause total blindness.
