INSTITUTO DE OTORRINOLARINGOLOGÍA

The Otolaryngologic Clinics of North America. 1989 Feb;22(1):1-14.

Sade J, Luntz M, Pitashny R.

Department of Otolaryngology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv, Israel.

Secretory otitis media (SOM) is a pathologic condition of the middle ear in which an effusion is present behind an intact ear drum without signs of acute inflammation. This definition covers a broad syndrome, and effusions that follow barotrauma or are secondary to carcinoma of the head and neck will not be discussed here. The majority of patients with SOM present an entity in which the cytological, bacteriological, biochemical, clinical, and histopathological characteristics point to an inflammatory condition, and it is with this entity that we are concerned in this article. This particular condition might perhaps be also viewed as a subacute otitis media, and may range from an extinguished acute middle ear inflammation to long-standing chronic situations.

SYMPTOMATOLOGY

The main symptom is a painless conductive hearing loss, varying in degree from mild to moderate. Adults and older children arc generally well aware of their hearing impairment and often also describe a sensation of fullness or a sensation of fluid shifting in the ear. Pain as such is absent and, when present, is usually associated with an acute episode into which SOM may relapse. Adults usually show great concern and irritation about their hearing loss, even if it is mild. However, young children—who are most frequently affected—often do not realize that their hearing has been affected. This is because the hearing loss develops insidiously and may be relatively mild, and also because young children are generally less capable than adults of linking such an effect with its cause. The hearing loss, even if unnoticed by the child, may have a marked effect on his or her behavior. Children with SOM frequently want the television or radio sound increased to a level that is irritating for a normal hearing adult and will often ask "what. . . what. . . what?" They may also become inattentive, dreamy, lazy, irritable, or nervous. Their poor responsiveness is sometimes misinterpreted as a manifestation of a primary behavioral disorder, and affected children may even be suspected of being slightly retarded. Early auditory deprivation may also result in enduring impairment of speech and linguistic and cognitive functions. It is also suspected of undermining intellectual development. Many of these children do not make good progress in school simply because they do not hear what the teacher is saying. However, whether this sets the pattern for the long term, as some have claimed, has yet to be confirmed. In classic cases, the dramatic improvement in the child's behavior following the correct treatment highlights the connection between these symptoms and the hearing loss associated with SOM, which averages only about 30 db.³

DIAGNOSIS

History

About 30 per cent of patients with SOM present with no significant medical history. Among children, in some 70 per cent of cases the parents may refer to a previous history of a cold, an upper respiratory tract infection, or an episode of acute otitis media. Many mothers know that their children "stop hearing" if they suffer from a cold in the winter and improve only when the weather becomes warmer. Acute otitis media treated with antibiotics often heralds a longer lasting middle ear effusion. It is suspected that the high incidence of SOM is a direct result of the failure to treat acute otitis media by paracentesis, which promotes drainage.

Otomicroscopy

The diagnosis of SOM is mainly based on an examination of the tympanic membrane. Proper otoscopy requires a clean ear canal and adequate illumination and magnification. Cleansing of the ear canal is best performed with the patient in the prone position and with the aid of suction apparatus while the ear is inspected using the surgical microscope. Otomicroscopy is obviously preferable to the use of a simple otoscope, since by using the otoscope it is difficult to remove the cerumen and debris that often interfere with adequate visualization of the tympanic membrane.

In cases of mucoid effusion the drum usually loses its translucency and becomes opaque, acquiring a gray-white, dull color and thick texture. At times the effusion glinting through the drum makes it appear as if it is studded with yellow spots. The pressure of the effusion in the middle ear may cause the drum to bulge slightly. When the effusion is serous it sometimes fills the tympanic cavity only partially, and the level of the fluid, at times with air bubbles, is visible through the drum. Vascular congestion, a sign of the quiet inflammatory component, is typically seen in the vicinity of the membrane's boarder.

In most SOM ears the fluid resolves before the drum becomes more seriously affected; in very persistent cases, however, the drum may begin to sink. Retraction is usually mild but may occasionally progress and become pronounced. These comprise most of the problematic cases in which long-term follow-up is especially necessary and in which chronic deficiency of middle ear aeration lingers in the background.

Pneumatic Otoscopy

When the drum becomes thick and loses its semitransparency it is almost impossible to see through it, even with the otomicroscope. The presence of an effusion in the middle ear may then be inferred by sluggish movement of the drum, detectable by the means of the pneumatic otoscope. Such movement corresponds to the B curve obtained by tympanometry, which essentially demonstrates poor drum mobility due to the impedance caused by the middle ear effusion. Air bubbles behind the drum are visible through the pneumatic otoscope as moving bubbles, and are a classic sign of serous effusion. Both of these features can best be viewed if the use of the pneumatic otoscope and the otomicroscope are combined by replacing the magnifying lens of the former with simple nonoptical glass.

Tympanometry

Although tympanometry is currently very popular as a means of detection of an effusion or changes of pressure in the middle ear, its value as a precise diagnostic tool is questionable. A certain percentage of tympanograms give false-positive or false-negative results. Moreover, it contributes little information beyond that given by the history, physical examination, and audiogram, and the experienced otologist may therefore find it superfluous. Tympanometry is more useful as a screening device for use by the general practitioner, pediatrician, school nurse, and epidemiologist, who do not routinely employ the otomicroscope. It may also be of some help in testing young children in whom audiometry is not yet practical.

Audiometry

SOM produces a conductive hearing loss of varying degrees (Fig. 2). The changes in stiffness as well as in mass of the middle ear acoustic apparatus affect both low and high frequency conductance, typically resulting in almost flat hearing loss. In most cases the audiogram shows an average loss of 28 db. It should be remembered that in mild cases little or not noticeable decrement may be present! This wide variation is probably related to the amount and type of fluid, its physical character (serous or mucous) and its exact location within the middle ear.

In children, it is not uncommon to find SOM superimposed on an independent nerve deafness; this may result in an overall hearing loss of up to 60 to 80 db. These are the patients who show the most obvious benefit from treatment, since reduction of this loss to 30 to 40 db represents an enormous improvement.

It should be noted that while audiometry is not essential for the diagnosis of SOM, it is nevertheless useful in revealing the extent to which the patient's hearing is affected and in measuring the effec­tiveness of treatment.

Screening

Screening for hearing loss or middle ear effusion in children at school and kindergarten is widely practiced; indeed such routine is considered as an indication of progress and commitment to public-health. Screening is usually done either by tympanometry of audiometry. However, since a large proportion of children suffer at one time or another from SOM episodes, which is in most cases mild and transient, the question arises of how important it is to detect them all. The use of tympanometry introduces an additional factor, owing to the relatively high incidence of false-positive results. Thus screening for middle ear effusion, even if competently done (which is not always the case), may result in "overdiagnosis," with unnecessary referrals to the otologist and possible overtreatment.

What is really very important, however, is to identify the children whose hearing loss is important, lasting, and therefore needs treatment. One way to do this is by educating parents and teachers to be alert to the possible signs and symptoms; for example, excessive day­dreaming, irritability, poor progress in school, or speech defects might indicate hearing difficulty in a child. If this approach were to replace current school screening procedures it might be found equally effective and less costly to society, while cutting down on undue referrals and treatment.

Pneumatization

Adults with protracted SOM usually show underdeveloped pneumatization, similar to that seen in ears with chronic otitis media. In children, the mastoid may not yet be fully developed. Our studies have shown that the more pneumatized the mastoid the better the prognosis, and that the course of disease is more protracted in patients with less pneumatization. This, however, is a statistical observation that cannot be applied to the particular case.

Adenoids

Enlarged adenoids are prevalent mostly in children aged 2 to 5 years, which is also the age at which mouth breathing and running noses as well as acute and secretory otitis media are common. While it is tempting to postulate a cause and effect relationship between enlarged adenoids and SOM, when the various studies on this subject are carefully examined, no definite answer is reached. It should be remembered that adults are devoid of adenoids altogether and many children (40 per cent according to Mawson') continue to suffer from SOM even after adenoidectomy. Adenoids should probably be regarded more as a potential source of infection in the middle ear than as an obstructor of the eustachian tube, that is, as a contributing factor rather than a pathogenetic one^. While most studies do not suggest that SOM can be cured by adenoidectomy, several maintain that a beneficial effect is seen. In a recent study, Gates identified a 10 per cent reduction in relapsing SOM when adenoidectomy was performed. It would probably seem reasonable to perform adenoidectomy in SOM-prone children who have large adenoids that merit removal for their own sake; however, some otolaryngologists believe that adenoids should be removed routinely.

Sinuses and Allergy

Although many physicians believe^, that SOM is at least partly an allergic manifestation, there is little concrete evidence to support this contention. Most of the evidence has the nature of clinical feeling; patients with SOM were not actually found to suffer more from allergic diseases or other allergic manifestations than a control group, and their effusions and blood counts did not contain abnormally large numbers of eosinophils. Moreover, their response to treatment with antihistamines and corticoids was not better than that of controls. It should be realized, however, that this controvertral point is not yet closed. Persistent chronic rhinitis, which is also often viewed as "allergic," is a negative prognostic factor for recovery from SOM; however, this could be explained by the possibility that SOM is part of the upper respiratory infection that affects both the nasal mucosa and the middle ear simultaneously. On the other hand, the disappearance of a chronic upper respiratory tract infection does not always lead to an improvement in SOM, and SOM may linger for years, especially in patients with poor mastoid pneumatization. Sinusitis is also considered by some physicians to play a pathogenetic role in SOM, but this has not been substantiated.

TREATMENT

SOM affects a large percentage of the population. Most children arc probably affected by it at one time or another, often so mildly that is passes unnoticed. Such mild cases are detected only if routine screening or epidemiological studies are carried out. These cases improve within a few weeks or few months. As the mild cases usually do not need treatment, (lie first priority is to decide at which point a patient needs treatment; thereafter, the question is what form treatment should be undertaken.

The aims of treatment arc

1.  To counter hearing loss if necessary

2.  To prevent recurrence of acute episodes in patients in whom SOM is part of a recurrent otitis media syndrome

3.   To prevent long-term middle ear complications, which arc seen in ears
that had a stubborn SOM in the past

When to Treat?

Patients may be divided into two groups, those who need immediate treatment and those in whom a spontaneous recovery may be expected. The same degree of hearing impairment does not necessarily affect all ages and all patients in the same way. Other than the hearing loss the effusion appears to cause no damage; however, this is not completely certain, as the effusion does often contain inflammatory factors that may cause damage to middle ear structures and possibly even diffuse into the inner ear. Furthermore, many children can tolerate a middle ear effusion and even some hearing loss without serious consequences. For example, a bright child may easily be able to compensate for the handicap, especially if the hearing loss is mild and short-lived. An entirely different situation is present in the less able child who is entering the first grade, especially if the hearing loss is prolonged and severe. The same degree of impairment would obviously be more deleterious in the second case, and early treatment would clearly be advisable. Thus, in deciding when to initiate treatment in children, the physician has to take several factors into account, including the child's age and scholastic ability and the extent and duration of hearing loss in one or both ears. If" only one ear is affected, which is the case in the minority of children, the healthy ear will compensate for the hearing loss finite well.

Adults, unlike children, are often seriously bothered by their middle ear effusion, and may be considerably disconcerted even by a mild unilateral hearing loss of 20 db. Prognosis in adults is generally less favorable than in children, especially in patients with poor mastoid penumatization, in whom SOM may persist for years. As in children, the criterion for initiation of treatment in an adult is the way in which the patient's hearing loss affects him or her. Thus the decision to treat, especially if surgery is contemplated, must be based on the physician's overall assessment of all the factors involved in each individual case.

Medical Treatment

A number of medical treatments have been claimed to cure SOM or to hasten its recovery. In spite of numerous claims, no convincing evidence has shown that any medical treatment is able to modify the natural course of the disease. The antihistamines, for example, are widely used on the grounds that they counter an allergic state; yet SOM is basically not an allergic condition, and antihistamines most probably act, at best, as a placebo. Despite the lack of convincing evidence that nose drops, corticoids, and antibiotics are of benefit in SOM, these are often routinely prescribed. This is in spite of the fact that nose drops can hardly reach the eustachian tube, that SOM is basically not an allergic manifestation, and that laboiatory tests show that many of the bacteria that are found in the effusion are already dead. Indeed, many of these patients have already received plenty of antibiotics at an earlier stage of the syndrome.

SOM may, at times, turn or relapse into an acute otitis media, and such an outcome can be prevented with antibiotics in some cases. However, patients with relapsing cases would do better if their effusion were drained rather than having it perpetuated with antibiotics.

Politzerization

During politzerization and autoinflation air is forced through the eustachian tube into the middle ear. These procedures often result in immediate hearing improvement, most probably by shifting the effusion in the middle ear. Unfortunately, the improvement is usually short-lived, lasting only 40 minutes to an hour, and does not change the course of the disease. It may, however, have an encouraging effect on the patient, who realizes that his or her hearing impairment can be alleviated.

Ventilation Tubes

The only effective treatment of hearing loss in a patient with SOM is surgical evacuation of the middle ear effusion. Unfortunately, evacuation alone is usually not enough; early recurrence of the effusion is common, probably because the mucosal glands of the middle ear remain active long after disappearance of the factor that originally triggered their excessive mucus production . Evacuation of the effusion by paracentesis should therefore be followed by an attempt to keep the paracentesis aperture open for a relatively long period in order to facilitate air entry into the middle ear and enable the cilia to evacuate the effusion through the eustachian tube . Such aeration can be achieved by the introduction of a ventilating tube into the middle ear, thus physically preventing its closure (Fig. 6).

Although the insertion of a ventilating tube is a relatively minor procedure, it has had a major impact on modern otology, as it is found to be the most efficient way to aerate ears in cases of SOM, as in atelectatic ear. A ventilating tube also helps to alleviate the symptoms in recurrent episodes of acute otitis media—and possibly reduces their number.

A large variety of ventilating tubes of different shapes and different materials is available. No one type has been proved superior to any other, and each surgeon tends to prefer the one to which he or she has become accustomed. Ventilation tubes are normally well tolerated. If inserted correctly, they will usually stay in place for about 6 months before being spontaneously expelled, by which time the mucosa will often have healed and will not need further ventilation. A certain proportion of patients may, however, require reinsertion of the tube, indeed some may even need repeated reinsertions, which may become rather frustrating for the parents. The question then arises of whether to use a longer term ventilation tube; with wide flanges such as a T-tube. T-tubes stay in place for a longer time, but the longer they remain in the drum the greater the chances of local complications developing. Skin debris from the drum, which would otherwise clear by finding its way to the outside, begins instead to accumulate around the tube, forming a convenient breeding ground for bacteria; thus, local infection sometimes develops. Discharging granulation tissue may also develop around a long-standing tube and, long-standing perforation occasionally follows the use of a T-tube. An infected tympanic membrane around a long-standing ventilating tube can be treated by local cleansing, usually performed with the suction apparatus, which is so disliked by children. This is best supplemented by local spraying with boric acid. Antibiotics have no effect. At times the T-tube induces so much local reaction that it has to be removed. Thus, although the use of T-tubes sometimes is helpful, this is by no means always the case, and candidates for this method of treatment should be carefully selected and the alternative explained. Actually, the greatest benefit of a T-tube is probably derived by those individuals who expel their regular ventilating tubes within weeks rather than after 6 months.

A ventilating tube can be introduced with the help of local or general anesthesia, depending on the state of the drum and the age and personality of the patient. Small children usually require general anesthesia, but the procedure^, is so short, and the level of anesthesia required so superficial that intubation is usually unnecessary unless adenoidectomy is to be performed at the same time. In older children and adults it is possible to achieve effective local anesthesia of the tympanic membrane, thereafter introducing the ventilating tube pain­lessly. The simplest procedure^, involves topical application of a drop of phenol at the site of incision. Following a slight burning sensation for 2 or 3 seconds, excellent local anesthesia will ensue. Cocaine and other mucosal local anesthetics, as well as procaine iontophoresis, do not penetrate the cornified cells of the drum sufficiently to achieve adequate anesthesia. Injection of flu^, ear canal with procaine will anesthetize the drum sufficiently, but this is by itself a painful procedure and consequently is used only in exceptional circumstances.

The incision can be made and the grommet placed in several parts of the drum, but care should be taken not to place the ventilating tube in the posterosuperior quadrant for fear of damaging the incudostapedial joint. We perfer to place it in the anterosuperior quadrant, taking care not to touch the mucosa of the medial wall of the middle ear. The incision should be the smallest which will enable the ventilating tube to be inserted and be held in place. Once the tube is in place, the action of the mucociliary system will clear the middle car of serous effusion, mucus, or mucopus through the eustachian tube. However, an attempt should be made to aspirate the fluid through the incision in order to avoid clogging of the ventilating tube in the immediate postoperative period. If the mucus is very thick, a second counter-incision (preferably below the umbo) may be helpful in allowing air to enter from one side while mucus is suctioned out from the other.

It should be borne in mind that while insertion of a ventilating tube probably has no curative effect perse, it offers satisfactory symptomatic treatment of hearing loss in SOM. As an additional advantage the ventilating tube provides immediate relief in any new episode of acute otitis media, while at the same time it probably reduces (he chance of recurrence.

A disadvantage of ventilating lubes is the potential for introduction of a middle ear infection when the patient is swimming. However, if children are cautioned not to dive, the risk is probably quite small.

Adenoidectomy

Although the therapeutic effect of adenoidectomy on SOM has not been confirmed by most authors, some authors have claimed its beneficial effect, and adenoidectomy is still widely practiced. The beneficial effect of adenoidectomy should probably be attributed to the removal of an ascending infective source near the opening of the eustachian tube rather than to removal of a supposed obstruction at the tube's entrance. The need for adenoid removal should not be based only on the ear disease; it should be also based on other indications such as the role of the adenoids in obstruction of breathing or a recurrent tendency to acute otitis media in the patient. While it is not a major procedure, adenoidectomy is nevertheless more complicated than insertion of a ventilating tube. The decision to operate therefore demands careful consideration on the part of the physician. Routine removal of the adenoids is probably not warrantee!.

Mastoidectomy

In stubborn cases of SOM simple mastoidectomy has been ad­vocated. However, its therapeutic value even in such cases is questionable.

The Hearing Aid

Use of a hearing aid might be advisable for patients with chronic SOM who cannot tolerate repeated insertions of a ventilating tube, or in whom the ear promptly starts to discharge once a ventilating tube is introduced.

PROGNOSIS

Although most patients with SOM eventually heal well, and quite quickly at that, a certain number of refractory cases persist even afterrepeated reinsertions of ventilating tubes. These are the patients who may develop atelectatic conditions, ossicular destruction and cholesteatoma. It is generally assumed that it is the long-term SOM itself that leads to these complications; however, it would be equally reasonable to assume that the factor responsible for the chronic character of the SOM, namely, poor long-term aeration of the middle ear, is the same one that will later lead to the abovementioned complications. Since these complications may cause irreversible damage to the middle ear structures, patients, especially those who have suffered a protracted course of SOM, should be followed for some considerable time after apparent recovery to make sure that no atelectasis, retraction pocket, or even cholesteatoma develops without symptoms.