By: Doctor Aldo Muñiz
Primary Healthcare Resident Medical Intern
The World Health Organization (WHO) defines hearing impairment (HI) as hearing loss over a threshold of 25dB; this definition includes hypoacusis, deafness and occupational deafness. 1
A significant loss of hearing can affect driving performance and safety.2 It tends to be accompanied by restrictions to everyday activities, affecting communication skills and people’s interaction with their environment, with significant physical, psychological and economic repercussions.3
In 2009, the WHO estimated the number of people worldwide with HI at 278 million. In Europe, around 71 million adults between the ages of 18 and 80 have hearing loss, and in Spain it is estimated that around 10% of the population aged between 6 and 65 have some form of HI. 4
The age group with the highest prevalence of this disability is older adults (over 65) and in this age group it is the third most common chronic disease. However, this is not the only age group affected, as studies carried out in Canada, the USA and Europe show that hearing loss is starting to occur 20 years earlier than in the past, so it is increasingly common to find hearing loss in young people. 5
HI can be classified according to its origin as follows:
- Sensorineural or perceptive hearing loss (for impairments that affect the cochlea, the auditory nerve or the neural pathways of the central nervous system).
- Conductive or transmitted hearing loss (difficulty in picking up normal sounds due to blockage of the outer ear, the tympanic membrane or other medium).
- Mixed (a combination of the above). 6
It is also possible to classify HI according to the degree of hearing loss:
- Mild: Hearing threshold at 41-71 dB.
- Average: Loss of hearing at 41-70 dB.
- Severe: Loss of hearing at 71-90 dB.
- Profound: Loss of hearing at over 90 dB, between 91-100 dB.
To diagnose HI it is necessary to conduct the correct anamnesis followed by the appropriate otoscopy and examination of the hearing function with specific tests. 3
- Anamnesis. For the correct anamnesis, particular attention should be given to the following aspects:
- How it started: whether it was sudden, within a period of less than 72 hours, often in just one ear (sudden deafness) or over a longer period of time in both ears (presbycusis).
- Whether there is any fluctuation or progression (autoimmune disease, acoustic neuroma).
- If the patient can understand spoken words or can hear them but not understand what is being said (presbycusis in the elderly, acoustic neuroma).
- If it gets worse in noisy places (sensorineural hypoacusis) or, in contrast, improves (otosclerosis).
- If it is associated with otorrhea or otalgia (otitis media, labyrinthitis, tumors in the external ear, tumors in the cavum).
- If it is related to scuba-diving, air travel or cranial trauma (barotrauma or temporal bone fracture).
- If there is a previous history of ear infections or surgery (iatrogenesis).
- If it is associated with tinnitus, vertigo or lack of balance (Menière’s disease).
- If there is a family history of hearing loss (family hypoacusis).
- If there has been previous or concomitant ingestion of ototoxic medications (ototoxicity).
- Otoscopy: The otoscopy focuses on examining the ears, hearing and neurological factors. With an otoscopy, the outer ear is examined to determine whether there are any blockages, infections, congenital deformities or other injuries. The tympanic membrane is examined to determine if there is any perforation, secretion, otitis media or cholesteatoma. During the neurological examination, special attention should be given to cranial pairs II and VII as well as the cerebellum and vestibular functions. The Weber and Rinne tests require a tuning fork to distinguish between conductive and sensorineural hypoacusis.
- Examination of auditory function with specific tests: There are numerous complementary examinations to help reach a diagnosis of hearing impairment. In the specific case of health and road safety, I will only mention the “Tone Audiometry” as this is the test that the Directorate General of Traffic uses to assess hearing acuity.
The tone audiometry is the essential test for patients with hearing impairment; it consists of identifying pure sounds emitted at different frequencies (from 125 Hz to 8 kHz) and intensities (from 0-120 dB). The result of this test enables us to clearly differentiate between conductive or perceptive hypoacusis and to establish the degree and percentage of hearing loss6.
Treatment of HI depends on the cause, the location and the severity of the hypoacusis. It can entail medical or surgical treatment or conventional hearing aids7.
With regard to the use of auxiliary hearing aids, it should be pointed out that the amplification of sound is of great help to many people, and even though these devices cannot restore normal hearing, they can significantly improve communication.
Doctors should encourage the use of hearing aids and help patients to overcome the social stigma that still stops people from using them, perhaps by making the analogy that hearing aids are to hearing what glasses are to sight4.
Regulations of the Directorate General of Traffic (DGT) concerning hearing impairments
The DGT, in section 2 of Appendix IV of the Royal Decree of the Official State Gazette on the physical and mental skills for obtaining or renewing a driver’s license, establishes two levels of combined hearing loss (CHL) for the two types of licenses (professional and standard).
The law requires that in order to drive there should not be a combined hearing loss involving both ears, with or without a hearing aid, of more than 45% for Group 1 (AM, A1, A, B, B+E and LCC) and of more than 35% for Group 2 (BTP, C1, C1+E, C+E, D1, D1+E, D, D+E), the level of this loss being obtained by an audiometry test.
Furthermore, whenever there is an impairment of one sense, the DGT requires this to be compensated by strengthening the ability of other senses, such as sight. In the case of hypoacusis, it is mandatory to use exterior rear-view mirrors and one panoramic rear-view mirror inside the car. This helps to increase the driver’s visual field.
The law also states that there can be no balance impairments (vertigo, lack of balance, dizziness, lightheadedness) whether permanent, progressive or intensive, of otological or any other origin. 8
Advice for patients with hearing impairment
The DGT (Directorate General of Traffic) has established the following guidelines:
- Hypoacusis due to “acoustic trauma” should be avoided by using helmets in noisy working environments and by following the recommendations of occupational medical services.
- People with hypoacusis who drive as part of their job must always check the positioning and orientation of rear-view mirrors in their vehicle to improve their visual field to compensate for the loss of hearing.
- Drivers should not drive with the radio/sound system turned up high as this hinders the perception of other sounds, whether emanating from the vehicle itself or from outside the vehicle.
- Drivers with a hearing aid should adhere to the guidelines for servicing and maintaining the prostheses to avoid a possible breakdown or acoustic distortions.
- When changing hearing prostheses (e.g. a different hearing aid model), you should avoid driving until you have fully adapted to the new device.
- After ear surgery, avoid driving for 3-4 weeks.
- Never drink alcohol before driving.
- Professional drivers on sick leave, or people who have to drive regularly for their work, should find out whether they may be breaking any legal regulation by driving while on sick leave.
- Patients being treated for balance impairments or vertigo must be made aware that the medication prescribed for these disorders can affect their driving ability9.
Since 2007, the WHO has been calling for greater awareness through its International Ear Care Day about hearing problems and the importance of early detection and prevention. General practitioners are usually the first point of contact for patients with HI and for this reason we need to be prepared to make the opportune diagnosis of any hearing acuity impairments. Doctors should always take into account the entire biological, psychological and social spectrum of the patient, and this includes their driving ability; we also have the obligation to provide guidance for the patient and his/her family members on all the issues associated with his/her disability.
Despite the reticence to use hearing aids shown by adult drivers and patients who have experienced traumatic hearing loss, we should encourage the use of hearing aids and other devices that can be recommended by specialists, such as hearing implants, according to the severity of the case in question, always paying particular attention to improving the patient’s quality of life.
For all patients whose driving ability may be compromised, whether due to diminished hearing acuity or for any other reason, we must be alert to the first signs of difficulty, asking the patient and his/her family members about possible pointers: damage to the car, passengers feeling uncomfortable about the driver’s ability, or even a history of accidents, without forgetting our important role in helping to prevent accidents.
- World Health Organization 2009-09-01. Accessed on 10 June 2009.
- Warshaw, G, Moqeeth, S. Hearing Impairment. In: Practical Ambulatory Geriatrics, Yoshikawa TT, Cobbs EL, Brummel-Smith K (Eds), Mosby, St. Louis 1998. p.118.
- Amor Dorado JC, Costa Rivas, C, Barreira Fernández Mdel P, Hipoacusis in adults. Ed. Elsevier. Spain 2014.
- Turiel Lobo M.P. Deafness. Chap. 2.12. Guidelines in Primary Healthcare by the SemFYC. 4ta Ed.SemFYC. Barcelona, Spain 2011.
- Chávez, M. Alvarez, Y. De la Rosa, A. Virgen, M. Castro, S. Hearing Deficits in Otorhinolaryngology Patients of the IMSS in Guadalajara. Rev. Med. Inst. Mex. Seguro Soc; 46 (3): 315-322
- Isaacson B. Hearing Loss. Med Clin North Am. 2010 Sep; 94(5):973-88. PubMed PMID: 20736107.
- Zadeh MH, Selesnick SH. Evaluation of hearing impairment. Compr Ther. 2001; 27(4):302-10. PubMed PMID: 11765688.
- Royal Decree 818/2009, of 8 M ay 2009, approving the General Regulations for Drivers.
- Healthcare Guidelines for Occupational Road Safety. DGT.