CLINICAL OBSERVATIONS IN 20 CASES OF POST-INFLAMMATORY MEDIAL MEATAL FIBROSIS

Takashi Goto, Tetsuya Tono, Keiji Matsuda

Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan

Background and purpose

Medial meatal fibrosis (MMF) has numerous synonyms, including post-inflammatory acquired atresia, post-inflammatory medial meatal fibrosis, chronic stenosing external otitis, and recurrent acquired atresia, which reflect both its etiological and histopathology.

Katzke and Pohl (1982) proposed a classification of the disease categorizing the etiological factors (inflammatory and traumatic).1 They reported cases of acquired atresia in which fibrous tissue in the medial portion of the external auditory canal developed as a consequence of chronic otitis externa, and called this condition post-inflammatory MMF (PIMMF), based on the morphology.

The purpose of this paper was to present our experiences with MMF.

Materials and methods

Over the past 20 years, The University of Miyazaki encountered a total of 20 (18 females and 2 males) cases of PIMMF. The patients’ ages ranged from 54 to 80 years, with a mean age of 63 years. All patients complained of hearing loss, 13 cases also complained of chronic otorrhea, and seven cases habitually scratched their ears with ear picks or cotton buds because of an itching sensation in the ear. Six cases presented with bilateral disease. The pre-operative pure-tone average was 63.5 dB, and the average air-bone gap was 29.2 dB. Pure-tone audiometric examination revealed conductive or mixed hearing loss in all affected ears. There was no surgical history in any patient.

All patients underwent CT studies using a TOSHIBA TCT/900S scanner with 0.5-mm contiguous sections with a semi-axial projection (OM line 20° downward). Auditory status: Pure tone averages were calculated using 0.5, 1, and 2 kHz. Air and bone from the same test were used to calculate the air-bone gap.

Treatment: Seventeen patients underwent surgery. Type-1 tympanoplasty was performed in 13 cases, and the others were performed in four cases.

Results

Pre-operative CT findings

CT scans were useful for assessment of the soft tissue thickness within the bony canal and associated middle ear pathologies if present. High-resolution computed tomography showed a soft tissue density occupying the medial portion of the external auditory canal. Typical CT findings are shown in Figure 1. A partially remaining tympanic structure was observed in some cases. Severe MMF was observed in two cases (Figure 2). Extension of fibrosis to the tympanic cavity was observed in three cases (Figure 3).

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Fig. 1. CT image (horizontal plane, right ear). A soft-tissue density area (arrow) in the medial aspect of the external auditory canal.

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Fig. 2. CT image (horizontal plane, right ear). Atresia in the cartilaginous meatus.

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Fig. 3. CT image (horizontal plane, right ear). Extension of MMF to the tympanic cavity.

Pre-operative associated CT findings

Bony stenosis was concomitantly formed in 17 cases, and bony defects of the anterior wall were observed in six cases. An attic retraction associated with MMF was formed in one case.

Operative findings

Seventeen patients underwent surgery. Twelve patients had an intact lamina propria of the tympanic membrane, and five patients showed perforations. Ten patients had an intact ossicular chain, three patients showed caries, and two patients showed tympanosclerosis and malleus ankylosis.

Post-operative hearing results assessed at least after one year following surgery (ranging from one to five years, mean: 1.5 years). Hearing results have been favorable, from a mean of a 63.5-dB pure-tone average and 29.2-dB air-bone gap preoperatively to a 46.8-dB pure-tone average post-operatively.

Hearing results

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Fig. 4. CT image (horizontal plane, right ear). Bony stenosis of the external auditory canal (arrow).

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Fig. 5. Evaluation of hearing results using the AAO-HNS guideline (n = 17).

Discussion

The term MMF was first described by Katzke and Pohl in 1982. In their article, the inflammatory or post-inflammatory medial meatal fibrosis was subdivided into an intact drum type and a perforated drum type. The traumatic type is subdivided into post-surgical, caustic, or external trauma. The PIMMF – intact drum type – is due to the fibrous healing of granulations resulting from either granular myringitis or granular otitis externa, and the perforated drum type is due to the organization of florid granulations resulting from chronic suppurative otitis media. In our study, all patients were diagnosed with PIMMF because of the existence of chronic inflammation in their affected ear for an extended amount of time. Twelve cases were the intact drum type and five cases were the perforated drum type. HRCT is useful not only to verify the presence of soft tissue thickening within the external auditory canal, but also to assess tympanic cavity involvement. The goal of MMF surgery was to remove the fibrous thickening of the subcutaneous tissue, creating a tympanic membrane as thin as possible, with preservation of the normal migration function of its skin layer. Additionally, the enlargement of the stenotic ear canal is important because 17 out of 20 ears with MMF had a concomitant bony stenosis. Hearing results of our series have been favorable, from a mean of a 63.5-dB pure-tone average and a 29.2-dB air-bone gap pre-operatively to a 46.8-dB pure-tone average post-operatively over an average follow-up period of 1.5 years. MMF is a good candidate for surgical treatment, but obviously a longer follow-up period is necessary for a stable canal skin condition.

References

1.Katzke D, Pohl DV. Postinflammatory medial meatal fibrosis, a neglected entity? Arch Otolaryngol 108:779–780, 1982

2.Bonding P, Tos M. Postinflammatory acquired atresia of the external auditory canal. Acta Otolaryngol 79:115–123, 1975

3.Magliulo M, Ronzoni R, Cristofari P. Medial meatal fibrosis; current approach. J Laryngol Otol 110:417–420, 1996

Address for correspondence: Takashi Goto, gotogoto@fc.miyazaki-u.ac.jp

Cholesteatoma and Ear Surgery – An Update, pp. 483–486

Edited by Haruo Takahashi

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