INSTITUTO DE OTORRINOLARINGOLOGÍA

Proceedings of The International Conference On ACUTE AND SECRETORY OTITIS MEDIA - PART I, JERUSALEM, ISRAEL 17-22 NOVEMBER 1985

CEREBROSPINAL FLUID MASQUERADING AS SECRETORY OTITIS MEDIA

RAUL PITASHNY

Instituto de Otorrinolaringología, Santiago del Estero 2722, (3000) Santa Fe - Republica Argentina

Secretory otitis media is essentially a condition in which an effusion is present behind an intact drum. However, the presence of fluid in the middle ear does not always mean secretory otitis media. Because this pathology is so important and frequent, we sometimes forget that there are other possibilities.

As it is necessary to think about it if we want to avoid a diagnostic mistake, I shall try to remind you with the cases I am reporting how cerebrospinal fluid in the tympanomastoid compartment can masquerade as a secretory otitis media.

Cerebrospinal fluid fistulae into the tympanic cavity may occur in association with congenital anomalies (Mondini dysplasia, dural defect), acquired diseases (infection, neoplasm), and trauma (fractures, surgical procedures).

In some cases, the diagnosis is aided by past history but there are other cases in which spontaneous cerebrospinal fluid otorrhea occurs without evidence that such a thing is happening either by history or examination.

1. Case reports

Case No. 1: A bilateral hearing loss developed in a 50-year-old man. He was treated without any satisfactory result for several months. He was a heavy smoker and suffered frequent episodes of  rhinitis and sinusitis 'specially in the right maxillary sinus.

At the age of 52, he was referred to us. The otoscopic examination revealed a fluid-filled right middle ear. The left tympanic membrane appeared normal. An audiogram showed a moderate bilateral sensorineural hearing loss with a 30 dB conductive component on the right.  X-ray films showed a cloudy tympanomastoid compartment on the right side.

A myringotomy was performed and a pressure-equalizing tube was introduced. The ear was dry for a few days  but  then  it began to discharge a clear watery fluid that did not stop any more. Finally, indium-111 was injected into the subarachnoid space and it appeared in the fluid recovered from the middle ear.

On the following day, an exploratory tympano-mastoidectomy was performed on the right side. A tumor mass was seen in the epitympanum. The site of origin was traced up to a defect in the tegmen tympani. The dura was involved by the tumor which was removed with the adjacent bone in order to expose the fistulae widely.

Temporalis fascia was placed over the defect and the area of the mastoid obliterated with Spongostan.

The biopsy specimen revealed a meningioma. Postoperative evaluation showed no further evidence of fluid or tumor in the middle ear. After seven years the patient is still in touch with us and is keeping well.

Case No. 2: At the age of 14 years this patient began to have problems in the left ear: otalgia and sometimes purulent otorrhea.

At the age of 37, the hearing loss in the left ear was subjectively worse and he felt unsteady on one occasion. He was treated with antibiotic drugs with only temporary relief of symptoms. We saw him at the age of 39; the tympanic membrane had a dull greyish-white appearance without evidence of inflammation. An audiogram showed normal hearing in the right ear and moderate conductive hearing loss in the left one. X-ray films revealed diffuse opacification of the mastoid air cells. A ventilation tube was inserted and this resulted in an improvement of hearing.

Three months later, the tube extruded from the tympanic membrane and the hearing loss had recurred.

Another ventilating tube was introduced and again he  obtained relief of symptoms for several months. After spontaneous expulsion of the ventilation tube the middle ear again filled with the fluid.

A left exploratory mastoidectomy was performed through a postauricular approach. Granulation tissue" and a dural defect were found in the tegmen tympani. Posteriorly, a small primary cholesteatoma invol­ing the ossicles was present, and I presume it was the original cause of the problem. All the pathology was removed and fascia temporalis was used to cover the defect.

When three years later, after a second look an ossicular reconstruction was carried out, the middle ear was free of pathology.

Case No. 3: At the age of 52, a woman first noted a sensation of fullness and right hearing loss. Her condition did not improve with antibiotic therapy. Her symptoms continued intermittently. Seven months later a myringotomy was performed and a ventilation tube inserted. During the following weeks, a profuse discharge of clear watery fluid was seen to issue from the tympanostomy tube. After a month the tube was removed and the hearing loss recurred.

When she was referred to us the otoscopic examination revealed a distended right tympanic membrane which was pale yellow. The audiometry showed a conductive hearing loss and a type B tympanogram was obtained on the right side.

X-ray films showed a cloudy mastoid on the same side. A ventilation tube was introduced and after two days of apparently dry ear, a constant watery drainage appeared.

Biochemical amlysis with a glucose level of 60 mg/dl and a chloride content of 130 mEq/1 were conclusive for the cerebrospinal fluid. The right ear was explored through a postauricular incision. The epitympanum was filled with granulation tissue and the site of the fistulous leak was identified in the dura of the tegmen tympani. The tumor-like tissue was removed and the fistulae sealed with perichondrium and cartilage.

The histopathologic findings showed an edematous fibrous stroma diffusely infiltrated with scattered mononuclear cells. No sign of malignancy was found. The postoperative course has been uneventful for two years.

2. Comment

The present report documents three cases in which cerebrospinal fluid in the middle car simulating serous otitis media was observed and treated erroneously during a certain period of time without the development of meningitis. Although these were lucky cases this is a potentially hazardous condition. The possibility of a spontaneous cerebrospinal fluid leak must therefore be considered in the differential diagnosis of middle ear effusion, particularly if the condition is unilateral.

First, a thorough search by past history and examination must be done for the possible cause of the fluid accumulation. Then a myringotomy and a ventilation tube insertion may be performed. If a watery fluid discharge appears with no signs of abating, we may suspect a cerebrospinal fistula. In this case the biochemical analysis of the fluid can be conclusive. Other tests like fluorescein dye or indium-111 may be helpful.

But even if the patient improves, it can still be a cerebrospinal fistula. In such cases (like No. 2), when the drum perforation heals the middle car and mastoid become again fluid filled.

The surgical exploration is mandatory and in some cases this will be the only way for achieving a correct diagnosis. Once the fistula is found it is necessary to remove the original pathology and cover it with a graft that can be made of different materials like fascia temporalis or perichondrium. If the bone defect is large enough, I prefer to reinforce it with cartilage or cortical bone.