A New Classification on the Morphology of Otosclerotic Foci SUBRATA 1V[UKHERJEE & B. K. ROYCHAUDHURI

On the b a s i s o f Morpho log ica l s tudy in 85 operated pat ients o f o tosc leros i s , a new c lass i f i cat ion o f the o tosc lerot ic focus i s made . -Nine types o f otosc lerot ie loci are found in th i s s t u d y and have been c o m p a r e d wi th the c lass i f icat ions m a d e by Garcla Ibanez (1969), D e s m o n d (1970), M o r r i s o n (1971) and M a w s o n and L u d m a n (1979).

Introduct ion Deafr~ess as a whole is a common

and frequent malady among the population of the most of the coun- tries of the world. Unlike congenital and senile deafness, otosclerosis, is a disease, in which primary patholo- gical change occurs in the periotic capsule as the common cause of non suppurative deafness in young and middle age group.

Guild (1944) and Nylen (1949) found that about 85 percent of oto- sclerotic loci are located in the oval window region. Strickland, Han- son and Anson (1962) have given an account of ossicular involvement in otosclerosis and footplate of stapes, as the site of otosclerotie focus.

Garcia Ibanez (1969) cIassified the otosclerotic footplate in his anatomical study into seven groups according to the location and exten- sion of the focus such as histological, marginal, crural, bifocal, annular, pseudo-obliterative and obliterative. Desmond (1970) classified the gross pathology according to the degree of involvement of the stapes into nine types. Morrison (1971) reported four degrees of stapedial otosclerosis macroscopically. Mawson and Ludman (1979) have classified the stapedial otosclerosis into four types according to macroscopic appea- orance of stapes footplate.

Subrata Mukherjee, P. G. Student. B. K. Roychaudhuri, Professor & Head, Department of ENT Surgery, Medical College & Hospitals, Calcutta-700 073. Formerly Head of the Deptt. of ENT Surgery, R. G. Kar Medical College & Hospitals, Ca!cutta-700 004. Read in the 39th Annual Conference of the Association of Otolarvngologists of India, held in Nandan, Calcutta, on the 4th to 7th January, 1987.

Address for Reprints Dr. B. K. Roy Chaudhuri, Govt. Housing Estate, Old Dog I1 ace Course, Block-LH, Flat-4, Calcutta-700 038.

TABLE I

Showing frequency o f type o f the footp late in 85 pat ients

Type of footplate Total No. Percentage

1. Marginal anterior 10 11.76 2. Marginal posterior 7 8.23 3. Bifocal 7 8.23 4. Marginal antero-inferior 3 3.52 5. Annular focus 20 23.58 6. Annular extensive focus 18 21.17 7. Pseudo-obliterative 3 3.52 8. Obliterative focus 10 11.76 9. Annular focus with posterior extension

from anterior 7 8.23

Total 85 100.00

With this background, art attempt has been made to study the otos- clerotic foci in clinical otosclerosis. The purpose is to make a rational classification of the morphology of otosclerotic foci, in relation to the footptate of stapes causing stapedial fixation producing conductive deaf- ness.

Mater ia l s and Methods

This study of morphology of otos- clerotic focus was carried out on the patients selected from audiology clinic of the Department of E.N.T., K. G. Kar Medical College and Hospitals. Calcutta, within a period of two years (1984-'85 and 1985286).

Eighty five deaf patients clinically diagnosed as otosclerosis, were in- cluded in this study.

All the patients were interrogated and assessed clinically, audiolo- gically, radiologicatly and then admitted into the indoor beds for tympanotomy and stapes surgery during which per operative micros- copic findings were noted. Photo- graph of otosclerotic focus was taken as and when suitable. Histological

examination of stapes footplate and the foci were done in a few cases.

Observat ions

The middle ear was examined after tympanotomy under the opera- ting microscope using magnification 9x. The morphology of otosclerotic focus, particularly its location, exten- sion, presence or absence of blue reflex were noted under the opera- ting microscope using magnification 9x and 13x

According to location and extent of the focus following types of footplate have been fotmd and accordingly they are grouped as Type-1 to Type-9 (Table I).

Type--1. (Marginal anterior)-- The focus is situated near the anterior margin of footplate and semilunar in shape or situated in the anterior half of footplate with superior and inferior prolongation in the posterior half.

Type--2. (Marginal pos ter ior) - The otosclerotic focus is situated in the posterior part of footplate i.e., near the posterior margin of footplate

114 Indian Journal of Ototaryngology, Volume 42, No. 3, September, 1990

A New Classi~cation on the Morphology of Otoscleroti¢ Foci--Mukherjee & Roychaudhuri

and semilunar in shape or situated in the posterior hal f of footplate with superior and inferior prolongation to the anterior half.

T y p e - - 3 . (Bifocal)- -There were two loc i - -one is situated in the anterior par t offootplate and another in the inferior par t of footplate without any continuity in between the two.

Type - - 4. (Marginal antero- infer ior ) - - T h e focus is situated in the anterior par t of footplate with prolongat ion inferiorly.

T y p e - - 5 . (Annular focus)-- A thin focus situated at the margin of the footplate al laround bu t wide central area is devoid of focus which remains thin and transparent. I t is described as blue reflex.

Type ~ 6. (Annular extensive focus) - - T h e whole of the stapedial footplate has been involved diffusely by otosclerotic focus except a small central port ion which remains thin and blue.

T y p e - - 7. (Pseudo-obliterative) The focus has involved the whole of the footplate except a slight rim in the inferior margin.

Type ~ 8. (obliterative focus) The focus is an extensive one affect- ing the whole stapes footplate, the crura and the oval window. The footplate is hard, there is no line of demarcat ion between the footplate and the oval window margin.

Type - - 9. (Annular focus with posterior extension from anterior) The focus is situated all round the footplate near the margin with linear prolongat ion from the middle part of anterior port ion posteriorly.

No otosclerotic focus was observed in patients under s tudy in round window region.

The annular focus in Type 5,6, and 9 comprises maximum number of cases i.e., 45 out of 85 ears (52.94 percent).

T A B L E II

M o r p h o l o g i c a l c l a s s i f i c a t i o n o f o t o s c l e r o s i s

Type of focus Nature of focus No. of patients Percentage

I Anterior 20 23.52 I I Posterior 7 8.23 I I I Bifocal 7 8.23 IV Annular 38 44.74 V Pseudo-ob literative 3 3.52 VI Obliterative 10 11.76

Total 85 100.00

D i s c u s s i o n

In this study of morphology of otosclerotic focus in 85 clinical otosclerotic patients, different types of morpbology are found and has been grouped into nine types.

Garcia Ibanez (1969) classified otosclerotic footplate in his ana- tomical study according to the loca- tion and extension of the focus into seven groups e.g., histological, mar- ginal, bifocal, crural, annular, pseu- do-obliterative and obliterative.

I n this study there is no such case with deafness having only histological otosclerotic lesion and was not evi- dent under operating microscope as in Garcia Ibanez ' study (Loc-cit).

Type - -1 , Type ~ 2, and Type 4 lesions of our study more or less correspond with Garcia Ibanez ' marginal group and only marginal anterior, marginal posterior and marginal antero-inferior lesions have been found in the cases under report which are grouped as Type - - 1, Type ~ 2, and Type ~ 4 lesions respectively.

Type ~ 3 lesion of our observa- tion correlates with the bifocal group of Garcia Ibanez but there is no such focus in this study similar to sym- metrical bicrural or bipolar form of his bifocal otosclerotic focus.

Type - - 5, Type - - 7 and Type 8 lesions of this report are in accor- dance with the annular, pseudo- obliterative and obliterative groups of Garcia Ibabez (Loc-cit) but

Type - - 6 and Type - - 9 lesions of this study do not correspond with any report.

Some findings of Garcia Ibanez do not conform with the findings of present study. For this discrepancy lack of uniform criteria to classify the otosclerotic footplate foci and durat ion of the disease (5 to 10 years) can be put forward, though no correlation could be ascertained in between the durat ion of the disease and extent of focus because some cases presented with a history of 10 years durat ion having only marginal antero-inferior lesion.

Desmond (1970) classified otos- clerotic footplate into 9 types (i.e., Type - - 1 to Type - - 9) according to the involvement of the otosclero- tic lesion.

Type - - 1, Type - - 2 and T y p e - - 4 focus of this study correspond with Type - - l, Type - - 2 and Type - - 4 lesions of Desmond's classification in some respects but are not exactly similar. Ty p e - - 3 (Bifocal) lesion of our findings is the same with Type J 3 lesion of Desmond's classification, with slight dissimilarity in relation to site of focus. Type - - 5 and Type - - 6 footplates of the cases under report do not conform with Desmond's classification bu t T y p e - 7 (Pseudoobliterative) and Type - - 8 (obliterative) footplates in this study more or less similar to Type - - 7 and Ty p e J 8 of Desmond's classification. But Type - - 9 footplate of the two studies are dissimilar in all respects.

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A New Classification on the )VIorphology o f Otosclerotic Foci--~VIukherjee & Roy Chaudhuri

Morrison (1971) described four degrees of stapedial otosclerosis macroscopically. T y p e - 1 and Type - - 2 lesions of the present work can be compared with Type - - i lesion of Morrison. Type - - 3,4,5, and 6 of this study have no corres- pondence with any type of 1VIorri- son's classification. Type - - 7 lesion of this study conforms with Type - - 3 of Morrison's to some extent but Type ~ 8 lesion i. e., obli terat ive footplate of this study is similar to T y p e - - 4 vea'iety of Morrison's classification.

Mawson and L u d m a n (1979) also have classified the stapedial otosclerosis into four types. Type 1, T y p e - - 2, Type - - 3, and T y p e

- - 4 lesions o f our study cart be compared with Type - - I lesion of Mawson and L u d m a n ' s classifica- tion. I n certain respect they are similar such as degree of fixation but in other respect such as intactness during removal of footplate f rom ovM window are not alike. No other lesions of this s tudy except Type - - 8

can be compared with Mawsor~ and Ludman ' s classification.

From the observation, it is evident that different authors have classified the otosclerotic focus in different ways. Based on our study and other published reports, a more simple, rat ional and acceptable classifica- tion is being put forward in Tab le I I

C o n c l u s i o n s

Statisfactory classification of the morphological study of the otosclero- tic focus is lacking in available literatures, No individual classifica- tion tallies with one another. Hence, a rational, simple arm acceptable classification has beert made after a thorough morp'~ological s tudy com- prising nirm types.

No correlation could be made between the morphological exten- sion of the disease with the degree of hear ing loss.

between the duratiort o f symptoms with the degree of hear ing loss.

No correlat ion could be m a d e in this s tudy between the dura t ion of disease, degree of hear ing loss and the site and extent of the pa tho logy with presence of 'Ca rha r t ' s notch ' .

R e f e r e n c e s

1. Desmond, A.F. (1970) : Otosclerosis-- An analysis of 1998 operations. Indian Journal of Otolaryngdogy, 2 : 1 I.

2. Garcia, I.J.L. (1969) : Anatomical study of Otoselerotic Footplate. Arch. of Oto. laryngology, 90 : 410.

Guild, S.R. (1944): Histologie Otos- clerosis. Annals of Oto, Rhino & Laryngol. 53 : 246.

4. ~awson, S.R. & Lundman, H. : Diseases of the ear. Fourth edition, Edward Arnold, London. p. 452.

5. Morrison, A.W. (1971): Acta. Oto. No correlation could be made Rhino. Laryngol., 25 : 898.

116 Indian Journal of Otolaryngology, Volume 42, No. 3, September, 1990