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National Journal of Maxillofacial Surgery
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Table of Contents
Year : 2012  |  Volume : 3  |  Issue : 2  |  Page : 195-198  

Unilateral coronoid hyperplasia treated by coronoidectomy using a transzygomatic approach

Department of Oral and Maxillofacial Surgery, Government College of Dentistry, Indore, Madhya Pradesh, India

Date of Web Publication4-May-2013

Correspondence Address:
Vilas Newaskar
Department of Oral and Maxillofacial, Surgery, Government College of Dentistry, Opposite M Y Hospital, Indore, Madhya Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0975-5950.111380

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Coronoid hyperplasia is a rare disorder, which effectively is a mechanical problem associated with limited mouth opening. In some cases, enlarged coronoid pushes the zygoma forward causing facial asymmetry. This article looks at the case of a 15-year-old boy reporting in OPD of Government College of Dentistry, Indore, with chief complaint of facial asymmetry. Transzygomatic approach was taken to get proper access to the enlarged coronoid. Coronoidectomy was performed which significantly reduced facial asymmetry. Postoperative healing was uneventful and recurrence was not reported.

Keywords: Coronoid hyperplasia, facial asymmetry, transzygomatic approach

How to cite this article:
Newaskar V, Idrees F, Patel P. Unilateral coronoid hyperplasia treated by coronoidectomy using a transzygomatic approach. Natl J Maxillofac Surg 2012;3:195-8

How to cite this URL:
Newaskar V, Idrees F, Patel P. Unilateral coronoid hyperplasia treated by coronoidectomy using a transzygomatic approach. Natl J Maxillofac Surg [serial online] 2012 [cited 2023 Feb 1];3:195-8. Available from: https://www.njms.in/text.asp?2012/3/2/195/111380

   Introduction Top

Coronoid hyperplasia is a rare condition which is macroscopically characterized by an increase in the dimensions of the coronoid process, resulting from an abnormal bony elongation of histologically normal bone. The most obvious clinical feature of this condition is reduced mouth opening associated with facial asymmetry. It generally occurs at puberty and continues over years. [1],[2],[3],[4] In addition to restricted opening, protrusion and lateral excursions may also be affected. [5] The cause of restricted mandibular movement is widely accepted to be an impingement of elongated coronoid process to the posterior aspect of the zygomatic bone, or to the inside of the zygomatic arch, at the mouth opening. [1],[3] Unilateral coronoid hyperplasia is usually due to a trauma or a pathologic condition and is associated with facial asymmetry, more frequently seen in women with histologic chondromatous or neoplastic changes most similar to ostechondroma. [4] However, others consider enlargement of the coronoid process to be a hyperplastic process rather than a true neoplasm. [1] The primary clinical feature of coronoid enlargement is limitation of opening. Shira and Lister [6] reported the appearance of bony enlargement of the zygoma on the affected side as demonstrated on a submentovertex radiograph. Athorough clinical history should include information about the onset and progression of pain and other subjective symptoms. In the case of coronoid hyperplasia, computed tomography (CT) is fundamental for a correct differential diagnosis. CT also allows surgical planning due to its accuracy to detect coronoid process volume and morphology. The following is a report of a case of unilateral coronoid enlargement with restricted opening as well as an obvious zygomatic asymmetry.

   Case Report Top

A 15-year-old male with no medical history of interest reported to the out-patient department of Government College of Dentistry, Indore, with the chief complaint of facial asymmetry [Figure 1].
Figure 1: Preoperative clinical photograph of the patient, revealing facial asymmetry

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The patient mentioned asymptomatic difficulty in opening his mouth. On examination, he was found to have a reduced mouth opening, with limited lateral and protrusive jaw movements and no hypertrophy of the masseter muscles [Figure 2].
Figure 2: Reduced mouth opening of the patient

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A CT scan was carried out with three-dimensional reconstruction­ (3D CT), showing unilateral hyperplasia­ of the coronoid process and contact between said process­ and the zygomatic arch, limiting mouth opening­ movement [Figure 3] and [Figure 4].
Figure 3: 3D CT reconstruction of face revealing facial asymmetry on left side of face

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Figure 4: Large anteroposterior extent of left mandibular Coronoid process as seen in three-dimensional CT reconstruction image

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Due to massive anteroposterior extent of coronoid­, transzygomatic­ approach was considered. [7] A hemicoronal­ incision ending in a preauricular extension up to the lobule of the ear was made through the skin, subcutaneous­ tissue, and galea. In the temporal region, this incision was up to superficial layer of the temporal fascia. At the root of the zygomatic arch, the superficial layer of temporalis fascia was incised anterosuperiorly at a 45° angle. The periosteum was incised to expose the zygomatic arch [Figure 5].
Figure 5: Hemicoronal incision was taken and zygomatic arch was exposed

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Two plates were adapted, bridging the osteotomy site on the zygomatic arch. The arch was osteotomized, temporalis muscle was stripped off the coronoid, and the process exposed adequately. An osteotomy cut was taken on the coronoid and the enlarged coronoid stump was removed [Figure 6].
Figure 6: Enlarged coronoid process mass removed

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Zygomatic arch was repositioned in its proper anatomic position and fixation was performed with titanium plates [Figure 7].
Figure 7: Repositioned zygomatic arch in its proper anatomic position and fixation done with titanium plates

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The wound was then closed in layers. Postoperative healing was uneventful. The patient reported after 6months with adequate mouth opening and marked reduction in facial asymmetry [Figure 8] and [Figure 9].
Figure 8: Marked reduction in facial asymmetry seen after 6 months postoperatively

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Figure 9: Increase in mouth opening appreciated 6 months postoperatively

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   Discussion Top

Elongation of the coronoid process of the mandible­ was described for the first time in 1853 by Von Langenbeckin­. In 1899, Jacob described a synovial joint formation between­ an elongated coronoid process and the homolateral­ zygomatic bone. Several approaches are advised by different authors for performing coronoidectomy, such as intraoral approach, submandibular approach, and coronal approach.

Since the coronoid was very large anteroposteriorly, we planned a transzygomatic approach. [7]

It can be difficult to establish the best time to administer treatment in infants or preadolescents, although most authors agree that except in patients with very severe limitation of the mouth opening, it is best to perform the operation once the growth process has finished in order to avoid recurrence, deformity, or even restricted movement. Obtaining a satisfactory outcome will depend­ largely on proper postoperative rehabilitation. Active physiotherapy is to be commenced immediately after surgery and continued for at least 6 months for satisfactory results. Postoperative cases of limitation of mouth opening caused by fibrosis, secondary to incorrect reorganization of a hematoma at the site of operation, and even recurrence in the growth of the coronoid process have been described. [8]

   Conclusion Top

Coronoid process hyperplasia as one the causes of mandibular hypomobility is largely underdiagnosed as it is a very rare entity, but a thorough clinical and radiological examination can help to rationalize the line of management and the ultimate clinical outcome. A case of unilateral coronoid enlargement is presented here. In addition to limited mouth opening, facial asymmetry was also a clinical finding. In case of massive anteroposterior extension of the coronoid, coronoidectomy with transzygomatic approach followed by active immediate physiotherapy gives satisfactory results.

   References Top

1.Hayter JP, Robertson JM. Surgical access to bilateral Coronoid hyperplasia using the bicoronal flap. Br J Oral Maxillofac Surg 1989;27:487-93.  Back to cited text no. 1
2.McLoughlin PM, Hopper C, Bowley NB. Hyperplasia of the mandibular coronoid process: An analysis of 31 cases and a review of the literature. J Oral Maxillofac Surg 1995;53:250-5.  Back to cited text no. 2
3.Giacomuzzi D. Bilateral enlargement of the mandibular Coronoid processes: Review of the literature and report of case. J Oral Maxillofac Surg 1986;44:728-31.  Back to cited text no. 3
4.Tucker MR, Guilford WB, Howard CW. Coronoid process hyperplasia causing restricted opening and facial asymmetry. Oral Surg Oral Med Oral Pathol 1984;58:130-2.  Back to cited text no. 4
5.Bell WE. Orofacial pains: Differential diagnosis. 2 nd ed. Chicago: Year Book Medical Publishers;1979. p. 224-9.  Back to cited text no. 5
6.Shira RB, Lister RL. Limited mandibular movements due to enlargement­ of the coronoid processes. J Oral Surg 1958;16:183-91.  Back to cited text no. 6
7.Kumar VV. Large osteochondroma of the mandibular condyle treated by resection using a transzygomatic approach. Int J Oral Maxillofac Surg 2010;39:188-91.  Back to cited text no. 7
8.Gerbino G, Bianchi SD, Bernardi M, Berrone S. Hyperplasia of the mandibular coronoid process, long term follow up after coronoidotomy. J Craniomaxillofac Surg 1997;25:169-73.  Back to cited text no. 8


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]

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