Vocal fold movement dysfunctions can be caused by functional disorders or organic processes in the central or peripheral nervous system. A degree of voice loss is the first symptom of vocal fold movement dysfunctions. After that, breathing difficulties occur.

The aetiology of functional paresis is compound, and – is still the subject of scientific research. Functional disorders of the larynx are divided into: phonastenia, pseudophonastenia, spastic aphonia and hysterical aphonia (7).

Ten percent of all cases are central paralysis. They are a part of a more compound clinical picture in disorders of the vascular system, brain inflammatory processes, multiple sclerosis, tumours, syphilis, syringomelia, bulbar syndrome, pseudobulbar syndrome and inferior posterior cerebellar artery syndrome (6, 7). Ninety percent of the cases are peripheral paralysis of the larynx muscles. This is due to the topography of these muscles (6, 7). The left recurrent laryngeal nerve originates from the vagus nerve to the front at the level of the arch of the aorta, and ascends into the groove between the trachea and oesophagus. The inferior laryngeal nerv e is the terminal branch of the recurrent laryngeal nerve. The inferior laryngeal nerve innervates the muscles of almost the whole pharynx, except the cricothyroid muscle, which is innervated by the superior laryngeal nerve. The left laryngeal nerve is extremely susceptible to disease processes in the thorax. The right recurrent laryngeal nerve originates from the vagus nerve at the level of the subclavian artery, curving round it from front to back and ascending.

Peripheral paralysis can be caused by the following: inflammatory factors – bacterial or viral infections; toxic factors – alcohol, haematological diseases, avitaminosis; compression factors – basal skull tumours, nasopharynx tumours, megalnodules of the neck, tumours of the superior part of the pharynx and trachea, tumours of the mediastinum, changes in the configuration of the heart and great vessels, lung and bronchi tumours; traumatic factors – basal skull fractures, iatrogenic complications during intubation, bronchoscopy, oesophagoscopy, operations on the neck, oesophagus, trachea, great vessels and the heart.

Studies on the vagus nerve carried out by many scientists have established the following classification for vocal fold paralysis (5, 7):

– a high lesion of the vagus nerve gives the intermedial position of the vocal fold,

– total breaking of the recurrent nerve gives the paramedial or medial position, but the vocal fold is not changed,

– unilateral paresis only of the internal branch of the superior laryngeal nerve causes no movement symptoms,

– bilateral paresis only of the external branch of the superior laryngeal nerves gives vocal fold relaxation and an inability to speak in a high voice. There are no voice changes in people that do not use their voice professionally,

– paresis only of the recurrent laryngeal nerve and the internal branch of the superior laryngeal nerve causes the paramedial position of the vocal fold, and abduction and rotation of the arytenoid cartilages.

Bilateral vocal fold paralysis causes dyspnoea, when it is paralyzed in the median and paramedian position. In the intermedial position rest dyspnoea cannot occurr. Dyspnoea occurs when the breathing surface of the glottis is decreased by 3/4. This condition needs prompt intervention as a rule (6).

Unilateral vocal fold paralysis does not cause breathing defects, and the defence function of the larynx is not disturbed as a rule. The type of voice disorder depends on the position of the vocal fold. In the medial and paramedial positions the voice can be unchanged, but in the intermedial position the voice is silent, aphonic or hoarse (7).

In the Paediatric ENT Clinic in Warsaw, from 1998 to 2003, 43 children with dyspnoea and voice disorders were admitted. In these patients the larynx was examined. In the Paediatric Radiology Clinic ultrasonographic examination of the larynx was made in children with phonation or breathing disorders. Then directoscopy was used to evaluate the anatomical structures and functions of the larynx. In this group of children, there were 12 girls and 31 boys with ages varying from 9 days to 3 years. In 27 of them congenital defects of the cardiovascular system were founed in the past, or cardiosurgical intervention had been performed. In 9 cases both congenital abnormalities and diseases of the central nervous system were found. In 2 cases neck trauma had occurred. In 5 children we could not establish the cause of the vocal fold paralysis.

Bilateral vocal fold paralysis occurred in 21 children. In these cases the children had tracheotomy.

Unilateral vocal fold paralysis was found in 22 children, of which 15 had left-sided vocal fold paralysis and 7 children right-sided.

In the whole group of children being examined, 14 had an intermedial position of the vocal fold, 16 paramedial position and 13 medial position.

In the history of 34 children with vocal fold paralysis there was coincidence with the appearance of congenital abnormalities and diseases of the central nervous system, as well as with the appearance of cardiovascular system disorders and surgical correction of those abnormalities.

Preliminary diagnoses were 100% confirmed by ultrasonographic examination of the larynx with a clinical diagnosis, while in the group of children with unilateral vocal fold paralysis there were 8 in whom differences in defining the side of vocal fold paralysis occurred.

Tracheotomy was done in children with bilateral vocal fold paralysis, which had led to considerable stenosis of airways.

The above – mentioned observations prove the usefulness of ultrasonographic examination (non-invasive examination) as a screening examination and for preliminary diagnosis (4).

Direct laryngoscopic examination is an invasive examination but enables direct inspection of the larynx, and the undertaking of diagnostic and therapeutic procedures.

In the literature there is information on genetic determination of vocal fold paralysis, which seems to be connected with the co-existence of other developmental disorders (2).

The return of proper function of vocal folds or improvement of their movement patterns took place in 18 children in the observation period between half a year and one year; 12 children are out of observation; 13 children remain under further observation (not longer than two years). In all children under our observation return of vocal fold functions appeared without the necessity for surgical intervention.

Therefore it seems that owing to the great regenerative potential of the child, return of the laryngeal nerves function occurs. However, this process depends on many factors, as pointed out by other authors (1, 3).

? Due to present progress in the field of medical science and techniques in the group of ill children with vocal fold paralysis, the share of children with congenital abnormalities and after reconstructive operations has increased.

? Paralysis of both vocal folds is a threat to the child and requires tracheotomy.

? New diagnostic techniques such as ultrasonography or genetic examination make it possible to reveal causes and confirm diagnosis in a quicker and more detailed way.

? Ultrasonography and directoscopy are supplementary examinations, and enable a quick diagnosis and determination of the future strategy.

? The great regenerative potential of the young organisms in the child allows full or partial return of laryngeal nerve functions.

? Laterofixation of the voice fold in children should be performed much more rarely and after a considerably longer period of observation than in Adult Person Clinics.