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Columella stapes
Columella stapes LARRY Z. MEITELES, MD, and STEFAN P. KIESERMAN, MD, Valhalla, New York
C o l u m e l l a r stapes describes the presence of one central crus and the absence of the normal stapes structure. Scheer 1 reported six columella stapes associated with other congenital anomalies and noted this to be the most common abnormality found. The footplate is approximately two thirds the usual length and width. The columella stapes tends to be formed by a broad, straight crus arising from the center of the footplate with a small head, lacking a stapedial tendon. The blastema of the stapes becomes recognizable at 4.5 weeks and is demarcated by the facial nerve. During the second fetal month the ossicles begin to take shape. The stapes blastema grows to enclose the stapedial artery and form the stapedial arch. During the seventh week contact is established between the developing cartilaginous mass of the ossicle (Reichert's cartilage) and the tissue of the otic capsule (lamina stapedialis). The lamina stapedialis will form the vestibular surface of the footplate and the annular ligament. Reichert's cartilage will give rise to the tympanic portion of the footplate and the stapes superstructure. By the fourth month the ossicles are formed. In the seventh and eighth months the middle ear space expands around the ossicles. The stapes arises from the second (hyoid) branchial arch and is independent of the malleus and incus. The stapes develops after the facial nerve. By the eighth week the orientation of the facial nerve within the temporal bone has been established. 2 The nerve needs only to migrate anteriorly over the area of the stapes blastema to disrupt normal development of this ossicle? The mechanisms of fallopian canal ossification do not play a role in facial nerve malposition. Malposition and malforFrom the New York Eye and Ear Infirmary, West Chester County Medical Center, New York Medical College. Received April 11, 1995; accepted April 14, 1995. Reprint requests: Stefan Kieserman, MD, New York Eye & Ear Infirmary, Department of Otolaryngology/Head and Neck Surgery, 37~0East 14th St., New York, NY 10003. Otolaryngol Head Neck Surg 1996;114:833-4. Copyright © 1996 by the American Academy of OtolaryngologyHead and Neck Surgery Foundation, Inc. 0194-5998/96/$5:00 + 0 23/11/65875
Fig. t. Columella stapes.
mation of the ossicles and facial nerve precede osseous facial canal development, and their ossifications are superimposed on these maldevelopments. Many theories have been proposed to explain stapedial crural and footplate malformations. Most have addressed general anomalies of the second branchial (hyoid) arch and the nerve to this arch (facial nerve). These theories include facial nerve malposition, anomalies and branching disorders, anomalies of facial vasculature, malfunctioning of primitive mesenchyme with defects in the laterohyale and interhyale, Reichert's cartilage failure or maldevelopment, a persistent stapedial artery or vascular obturator, a stapedial maldevelopment, and a variety of other theories. Jahrsdoerfer et al. 3 described four patients with Treacher Collins syndrome whose stapes were "monopodal." Weber et al. 4 described 94 patients with congenital perilymphatic fistula and found 39 to have a malformed stapes. Weber et al. describe two types of columellar stapes: type I, having a missing anterior crus and a normal posterior crus, found in 11 ears; and type II, a monopod stapes in which a single crus was located in the middle of the footplate, found in 12 ears. 833
Otolaryngology Head and Neck Surgery June 1996 -
834
MEITELESand KIESERMAN
The diagnosis of congenital conductive hearing loss is associated with (1) a marked conductive deafness in early childhood that is greater than that which could be caused by an acquired pathologic process; (2) lack of progression of the hearing impairment; and (3) rather typical audiometric findings of fiat air conduction loss at 50 to 60 dB level, associated with a fiat bone conduction curve approximating the zero level.
REFERENCES
1. Scheer A. Correction of congenital middle ear deformities. Arch Otolaryngol 1967;85:269-77. 2. Jahrsdoerfer RA. Embryology of the facial nerve. Am J Otol 1988;9:423-6. 3. Jahrsdoerfer R, Aguilar E, Yeakley J, Cole R. Treacher Collins syndrome: an otologic challenge. Ann Otol Rhinol Laryngol 1989;98:807-12. 4. Weber P, Bias P, Bluestone C. Congenital perilymphatic fistula and associated middle ear abnormalities. Laryngoscope 1993; 103:160-4.
C o l u m e l l a r stapes describes the presence of one central crus and the absence of the normal stapes structure. Scheer 1 reported six columella stapes associated with other congenital anomalies and noted this to be the most common abnormality found. The footplate is approximately two thirds the usual length and width. The columella stapes tends to be formed by a broad, straight crus arising from the center of the footplate with a small head, lacking a stapedial tendon. The blastema of the stapes becomes recognizable at 4.5 weeks and is demarcated by the facial nerve. During the second fetal month the ossicles begin to take shape. The stapes blastema grows to enclose the stapedial artery and form the stapedial arch. During the seventh week contact is established between the developing cartilaginous mass of the ossicle (Reichert's cartilage) and the tissue of the otic capsule (lamina stapedialis). The lamina stapedialis will form the vestibular surface of the footplate and the annular ligament. Reichert's cartilage will give rise to the tympanic portion of the footplate and the stapes superstructure. By the fourth month the ossicles are formed. In the seventh and eighth months the middle ear space expands around the ossicles. The stapes arises from the second (hyoid) branchial arch and is independent of the malleus and incus. The stapes develops after the facial nerve. By the eighth week the orientation of the facial nerve within the temporal bone has been established. 2 The nerve needs only to migrate anteriorly over the area of the stapes blastema to disrupt normal development of this ossicle? The mechanisms of fallopian canal ossification do not play a role in facial nerve malposition. Malposition and malforFrom the New York Eye and Ear Infirmary, West Chester County Medical Center, New York Medical College. Received April 11, 1995; accepted April 14, 1995. Reprint requests: Stefan Kieserman, MD, New York Eye & Ear Infirmary, Department of Otolaryngology/Head and Neck Surgery, 37~0East 14th St., New York, NY 10003. Otolaryngol Head Neck Surg 1996;114:833-4. Copyright © 1996 by the American Academy of OtolaryngologyHead and Neck Surgery Foundation, Inc. 0194-5998/96/$5:00 + 0 23/11/65875
Fig. t. Columella stapes.
mation of the ossicles and facial nerve precede osseous facial canal development, and their ossifications are superimposed on these maldevelopments. Many theories have been proposed to explain stapedial crural and footplate malformations. Most have addressed general anomalies of the second branchial (hyoid) arch and the nerve to this arch (facial nerve). These theories include facial nerve malposition, anomalies and branching disorders, anomalies of facial vasculature, malfunctioning of primitive mesenchyme with defects in the laterohyale and interhyale, Reichert's cartilage failure or maldevelopment, a persistent stapedial artery or vascular obturator, a stapedial maldevelopment, and a variety of other theories. Jahrsdoerfer et al. 3 described four patients with Treacher Collins syndrome whose stapes were "monopodal." Weber et al. 4 described 94 patients with congenital perilymphatic fistula and found 39 to have a malformed stapes. Weber et al. describe two types of columellar stapes: type I, having a missing anterior crus and a normal posterior crus, found in 11 ears; and type II, a monopod stapes in which a single crus was located in the middle of the footplate, found in 12 ears. 833
Otolaryngology Head and Neck Surgery June 1996 -
834
MEITELESand KIESERMAN
The diagnosis of congenital conductive hearing loss is associated with (1) a marked conductive deafness in early childhood that is greater than that which could be caused by an acquired pathologic process; (2) lack of progression of the hearing impairment; and (3) rather typical audiometric findings of fiat air conduction loss at 50 to 60 dB level, associated with a fiat bone conduction curve approximating the zero level.
REFERENCES
1. Scheer A. Correction of congenital middle ear deformities. Arch Otolaryngol 1967;85:269-77. 2. Jahrsdoerfer RA. Embryology of the facial nerve. Am J Otol 1988;9:423-6. 3. Jahrsdoerfer R, Aguilar E, Yeakley J, Cole R. Treacher Collins syndrome: an otologic challenge. Ann Otol Rhinol Laryngol 1989;98:807-12. 4. Weber P, Bias P, Bluestone C. Congenital perilymphatic fistula and associated middle ear abnormalities. Laryngoscope 1993; 103:160-4.