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Hearing and Vestibular Disorders Related to Head Injuries

I. Jovchev, S. Konsulov, A. Beshkova, D. Pazardzhikliev

Clinic of Ear-Nose-Throat Diseases, Medical University, Plovdiv, Bulgaria

ABSTRACT

Objective: To assess the vestibulo-cochlear disorders in relation to severity of head injury and to define the characteristic of the course of the disease at follow-up.
Study Design: Randomized study
Setting: ENT department, department of Neurosurgery, HMI Plovdiv, Bulgaria.
Patients: 82 patients – 55% men and 45%-women, the majority were aged from 31 to 50 years.
Interventions: Pure tone audiometry, tympanometry, acoustic reflex testing, observation of spontaneous vestibular symptoms, caloric testing, electroencephalography.
Main Outcome Measures: Results of diagnostic tests and changes during follow-up.
Results: Three groups of patients: Group1 (hearing loss only) – 6 patients (3 had conductive hearing loss, 1 - sensorineural hearing loss with absence of acoustic reflex, 2 - combined hearing loss with the presence of recruitmen phenomena). Group 2 (vestibular disorders only) – 38 (29 of the patients were followed-up (1 to 4 years). Vestibular disfunction developed gradually. Patients reported for aggravation of some symptoms i.e. vertigo – 29 patients, headache – 32 patients. Changes in the electroencephalography were also observed; Group 3 (cochleo-vestibular disorders) –38 patients (5 had combined hypacousis, 33 - sensorineural hearing loss. Auditory changes in these patients were accompanied by vestibular complaints, and in many cases the latter forced the patients to seek medical help.)
Conclusions: Auditory and auditory-vestibular damages are more frequent in cases of severe head trauma, while in cases of slight injuries prevail vestibulo-vegetative symptoms.
Vestibular symptoms develop later. Compensation occurs later and depends on neurovegetative characteristics before the trauma.
Timely examination is of major significance for the thorough diagnosis and treatment.
Key words: Head trauma, Auditory damages, Vestibular damages and symptoms.
Pro Otology 3: 123-125, 2002

INTRODUCTION

The cochleovestibular analyzer demonstrates its sensitivity in every case of injury to the head and the central nervous system (1). The impairments are numerous and complicated: in the conductive system of the middle and inner ear, the peripheral receptor, the roots of n. statoacousticus, the auditory nuclei and pathways in the medula, auditory cortex.

At the early stages the changes are difficult to detect since the clinical presentation is dominated by the symptoms from the central nervous system, and since the auditory analyzer is bilateral organ. The patients either are unable to detect the unilateral hearing disorders or quickly get used to them. The objective examination is hindered by the changes of consciousness and the injuries to head. In many cases the functional disorders of cochleovestibular system are the only signs of head injuries and their examination is compulsory for establishing the thorough diagnosis.

MATERIALS AND METHODS

We examined 82 patients – 55% men and 45%-women between 10 and 20 days following the accident. The age distribution is shown in Table 1.

It comes into view that the majority of patients are in the age of active life. The taumas are predominantly domestic – 55%, traffic – 34%, industrial – 11%. 50% of the patients had different degrees of changes of consciousness that lasted from minutes to 22 days. The methods we used for examination of hearing included pure tone audiometry and tympanometry with acoustic reflex testing, and the methods for evaluation of vestibular analyzer were the observation of spontaneous vestibular symptoms and caloric testing.

RESULTS AND DISCUSSION

Otoscopy revealed bleeding in 6 patients, deformity of the external auditory channel - in 2 patients, traumatic rupture of the tympanic membrane - in 6 patients, heamatotympanon – in 3 patients, and traumatic suppurative otitis - in 1 case. These observations were supported by the respective changes at tympanometry. In the rest 64 cases we did not observe any abnormalities at otoscopy and tympanometry.

We divided patients in 3 groups (Table 2).

Table 1. Distribution by age. Patients.

Table 2. Patients grouped by types of disorders.

The first group had only hearing impairment without vestibular changes. In this group 3 patients had conductive hearing loss, one had sensorineural hearing loss with absence of acoustic reflex, two patients had mixed hearing loss with the presence of recruitmen phenomena that revealed cochlear damage.

Hearing loss in the range of high frequencies for the contralateral ear is detected as a rule (2). We found this in 3 patients.

Vestibular disorders are amongst the most frequent and objective signs of injury to the central nervous system. The localization of the damage, its degree, the stage of the disease, and the degree of compensation and adaptation should be elicited (3).

The majority (29) of the patients with slight injuries from group 2 were followed-up (1 to 4 years). It is characteristic that vestibular disfunction develops gradually. Patients reported for aggravation of some symptoms i.e. vertigo – 29 patients, headache – 32 patients. At the same time changes in the electroencephalography were observed – raised tension of the vessels and hindered venous drainage in the region of a. vertebralis and a. basilaris – 20 patients. These changes are due to the disrupted circulation in the peripheral and central part of the analyzer following the trauma (4,5). The late vestibular disorders are considered to be the major components of the posttraumatic disease. The vertigo is extremely frequent – 28 patients, 14 patients had changes at statocynetick tests, and 9 had nystagmus.

In 4 patients with severe trauma at the early stage (1-10days) we found prominent vestibular symptoms. These had defined characteristics – sudden onset, but gradual compensated and abated. The majority of the follwed-up patients suffered a single trauma – 33 patients, 5 suffered multiple trauma. It comes into view that in cases with repeated trauma the vestibular disorders – vertigo, dysequillibrium, early nystagmus – were more frequent, more stable, and lasted longer. This gives the characteristics of the posttraumatic disease of the central nervous system (4).

Disorders of vestibular excitation are frequent objective sign of single head trauma at the early stage, while for the repeated injuries these are a constant sign (6). In our series 5 patients had areflexy, and 14 hyporeflexy at caloric testing.

Mixed - cochleovestibular disorders are usually consequences of severe head trauma (7). In group 3, 11 patients had fracture of the cranial base, and 5 of the calvaria, 3 of which in the region of the temporal bone and one with a fracture of the facial skeleton. 8 patients had subarachnoid haemorrhage. 8 patients had facial nerve paralysis, and 2 had anosmy following the trauma.

We found combined hypacousis only in 5 patients. The rest 33 patients had sensorineural hearing loss that ranged from mild to profound deafness in 14 patients, who also had absence of acoustic reflex, and 3 of which were deaf with both ears. In 13 patients we found unilateral sensorineural hearing loss, 3 of which had recruitman indicating cochlear damage. In cases of unilateral disorders, the contralateral ear showed slight impairment, which is characteristic for central nervous system trauma.

Bilateral equal hearing loss was found in 6 patients, with one patient with recruitmen . The rest 5 patients had retrocochlear damage, which determined the sensorineural hearing loss. Auditory changes in these patients were accompanied by vestibular complaints, and in many cases the latter forced the patients to seek medical help. We found dynamic and static ataxy in 27 patients, spontaneous nystagmus in 18, and positional – in 4 patients. Caloric testing at later stage revealed hyporeflexy in 18 patients, and in 11 patients with fracture of the pyramid areflexy – total damage of the vestibule.

For recognizing the retrolabyrinth damages, examination of the cranial nerves passing through or nearby the pyramid can also be used. In 9 patients we found sensitive impairment for the region of n. trigeminus, and in 8 patients ageusia for the anterior two thirds of the tongue.

In 15 of the cases cochleovestibular disorders were due to traumatic damages to the receptor. In the rest of the cases they were due to damages to the retrolabyrinth structures. We found receptoro-root syndrome in 16 patients. Simultaneous impairment of the labyrinth and of the central structures we found in 10 patients. 6 of them had deafness accompanied by spontaneous medular nystagmus and 4 patients had diencephalocortical syndrome with vigorous vegetative and sensory reactions and suppressed nystugmus at caloric tests. Three of them had developed cerebral form of hypertonic disease after the trauma.

CONCLUSIONS

Auditory and especially the auditory-vestibular damages are more frequent in cases of severe head trauma, while in cases of slight injuries prevail vestibulo-vegetative symptoms.

Vestibular symptoms develop later, depending on the severity of the trauma. Compensation occurs later and depends on neurovegetative characteristics before the trauma.

Timely examination is of major significance for the thorough diagnosis and treatment as well as for the labour expertise and forensic medicine.

REFERENCES

  1. Maerovich IM Trauma to the brain and the hearing. Moscow Medicine 1975.

  2. Scot AM, Bauch CD Olsen Wo. Head trauma and mild - freqency hearing loss American journal of audiology 1999;12:8-12.

  3. Blagoveshtenskaia NS. Otoneurological symptoms and syndromes. Moscow 1995;292-308.

    4. Kupriashkin E. Electronystagmographic signs of vestibular and optocynetick disorders following head injury Vestnik Otorhinolaryngologii 1987;4:34-7.

  4. Preobrazhenski, Konstantinova, Guseinov. Acute sensorineural hearing loss as a consequence of trauma to the brains. Vestnik Otorhinolaryngologii 1988;3:23-6.

  5. Consensus conference Rehabilitation of persons with traumatic brain injury. JAMA 1999;8:282-4.

  6. Lee D, Hourado C, Har-El, Goldsmith. Pediatric temporal bone fractures. Laryngoscope 1998;6:108-16.

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