Poster Presentation New Zealand Association of Plastic Surgeons ASM & AGM

Bilateral mastoid process hypertrophy associated with severe trismus (1262)

Kimberley Dr Sent-Doux 1 , Swee Dr Tan 1 2 3 , Mark Prof Moore 4
  1. Plastic and Reconstructive Surgery, Hutt Hospital, Wellington, New Zealand
  2. Gilles McIndoe Research Institute, Wellington, New Zealand
  3. Department of Surgery, The University of Melbourne, Parkville, Victoria, Australia
  4. The Australian Craniofacial Unit, Adelaide, South Australia, Australia

Background

Trismus is defined as restricted mouth opening and affects 5-38% of the population. The mastoid process is a pneumatized prominence of the temporal bone with air-filled air cells that grows with age. The aetiologies of trismus are broadly divided into intra-articular or extra-articular factors that affect the temporo-mandibular joint (TMJ). Previous descriptions of locoregional changes in patients with trismus have focused on coronoid process overgrowth.

Methods

We present a series of four patients with severe trismus from different aetiologies with bilateral mastoid hypertrophy and discuss the possible explanation.

Results

Case 1 was a 66-year-old male with severe trismus with mouth opening of 4mm, secondary to a previous fall and unrecognised bilateral intracapsular condylar fractures of the mandible. Case 2 was a 21-year-old male with severe trismus, no mouth opening caused by recurrent ankylosis following pan facial fractures. Case 3 was a 53-year-old-male with severe trismus with mouth opening of 3mm due to bilateral congenital TMJ ankylosis secondary to juvenile arthritis. Case 4 was a 14-year-old girl with severe trismus with no mouth opening, following right TMJ infection during childhood. CT scans of all four patients showed bilateral hypertrophic and elongated mastoid processes with extensive pneumatisation and increased volume of the mastoid air cells.

Conclusion

We hypothesise that the hypertrophy of the mastoid process in these cases of severe trismus is due to the chronic bilateral muscular strain, probably from the sternocleidomastoid muscle. To our knowledge, this is the first report of bilateral mastoid hypertrophy associated with severe trismus.

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