Hemifacial microsomia and the manifestations of the condition
Hemifacial microsomia is a congenital condition where one side of the face is underdeveloped with the eyes, ears, cheekbone and mandible being affected. The lower half of the face is affected the most by this condition. Underdevelopment of the mandible includes underdevelopment of the TM joint. Hemifacial microsomia always results in TMJ disorders. This can result in serious structural and functional disorders of the TMJ. One manifestation of this condition is extreme facial asymmetry. Normal alignment between the upper and lower jaws is also lost.
Other symptoms of hemifacial microsomia include an extremely wide mouth, skin flap present over an underdeveloped external ear and growths around the eye on the affected side.
Normal and abnormal relationship between the upper and lower jaws
Normal alignment of the teeth is called normal occlusion. Normal occlusion of the teeth signifies normal alignment of the maxilla and the mandible. Normal alignment of the jaws can also be present in cases of abnormal relationship between the teeth of the upper and lower jaws. This is called dental malocclusion and correction of this is through fixed orthodontic treatment. Dental malocclusion can also result when there is abnormal alignment between the two jaws. This is known as skeletal malocclusion. Skeletal malocclusion can only be corrected through surgery. Surgery that is performed to correct the relationship between the two jaws is known as orthognathic surgery.
Manifestations and etiology of hemifacial microsomia
TMJ symptoms begin to manifest early in life for these patients. There is also a lot of TMJ pain. Most cases of hemifacial microsomia occur as the result of a combination of genetic and environmental factors. It causes serious problems with the patient’s general health as well as oral health. Relaxation techniques do not help with pain arising from this condition as it is caused by a structural deformity. Clinical trials are constantly being performed around the world to help alleviate the symptoms in the long term.
The temporomandibular joint is the only movable joint in the skull. It is the point of contact between the mandible and the skull. The joint has a cartilaginous capsule that provides synovial articulation between the glenoid fossa of the temporal bone and the mandible. There are a variety of disorders that lead to disruption in the functioning of this joint.
Fractures of the TMJ are very common as any blow to the chin is directly transmitted to the joint. The condylar fractures of the mandible are amongst the most common facial fractures. Only nasal bone fractures occur in greater numbers. Common causes of condylar fractures are road traffic accidents and interpersonal assaults.
Classification of disorders of the TMJ
There are many conditions that lead to disorders of the TMJ. They can be broadly classified into congenital, traumatic, idiopathic, degenerative and inflammatory disorders. Congenital disorders include absence of the joint at birth, smaller than normal or larger than normal joint and abnormally developed joint.
Traumatic disorders include dislocation, subluxation and fracture. An idiopathic disorder of the TMJ is defined as one where there is pain and dysfunction of the joint without any identifiable cause for the symptoms. Inflammatory disorders include myositis, capsulitis and synovitis. Degenerative disorders include rheumatoid and osteoarthritis.
Benefits of surgery in patients with temporomandibular joint disorders
Oral and maxillofacial surgeons always recommend surgery for this condition. There is overall improvement in the patient’s health once surgery is performed. Physical therapy in the form of jaw exercises has to be performed regularly to maintain good joint health following surgery. Surgery for hemifacial microsomia however is not an orthognathic surgery or corrective jaw surgery. This can be categorized under temporomandibular disorders that require TMJ reconstruction surgery.
Patient with hemifacial microsomia with worsening mandibular deviation
The patient is an 8-year-old girl with right-sided hemifacial microsomia. She also has microtia of her right ear and underdevelopment of her mandible with deviation to the right side. She had first undergone right-sided jaw reconstruction surgery elsewhere when she was 3 years old. However, over the course of time, her right-sided mandibular deviation had gotten worse with development of an open bite and her parents consulted with a plastic surgeon.
Referral to our hospital by a plastic surgeon in her hometown
The plastic surgeon examined the patient and explained to the parents that the patient needed TMJ surgery for temporomandibular joint reconstruction, which came under Oral and Maxillofacial Surgery. He explained that the American Association of Oral and Maxillofacial Surgeons (AAOMS) had developed a protocol for surgical treatment of this condition. Only certain hospitals in India met the stringent standards prescribed by the AAOMS for TM joint surgery.
The patient was thus referred by him to Balaji Dental and Craniofacial Hospital. It was explained to the parents that the cost of temporomandibular joint reconstruction surgery in India was a fraction of what it cost in other countries with an excellent infrastructure for healthcare.
Examination and treatment planning at our hospital
Dr SM Balaji, an experienced temporomandibular joint reconstruction surgeon, examined the patient. He then ordered a 3D CT scan and other pertinent imaging studies. This protocol is standard for determining the best treatment option for the patient. These diagnostic studies revealed that the patient had extreme resorption of the costochondral rib grafts that had been placed during the previous surgery. Detailed treatment planning was done and it was decided to reconstruct the temporomandibular joint with rib grafts. This was explained to the parents of the patient in detail and they consented to the proposed treatment plan.
Dr. SM Balaji is an experienced TMJ surgeon who has published many articles on the jaw joint surgeries performed by him in many international scientific journals. Many cases of hemifacial microsomia have been surgically rehabilitated at our hospital. Postsurgical follow up of over ten years has shown excellent results with the patient leading active lives that were fully integrated into their society.
Harvesting rib grafts for jaw reconstruction surgery
The patient was taken to the operation theater where she was prepped and draped for surgery. Under general anesthesia, two rib grafts were first harvested from the patient. These were harvested with the periosteum to ensure that the grafts would not resorb after reconstruction of the temporomandibular joint. A Valsalva maneuver was then performed to ensure that there was no perforation into the thoracic cavity. The incision was then closed in layers with sutures.
Jaw joint reconstruction using rib grafts
Attention was next turned to the right side of the mandible. A buccal vestibular incision was first made to expose the region of the mandible to be reconstructed. It was seen that the rib grafts used to reconstruct the mandible in the previous surgery had nearly fully resorbed. The rib grafts that had been harvested from the patient were then carefully shaped to attain the right anatomical dimensions of the patient’s jaw. These were then joined together using titanium plates and screws.
This was then placed in the region of the jaw to be reconstructed and fixed with titanium plates and screws to the right side of the mandible. Postoperative radiographs revealed perfect reconstruction of the right-sided temporomandibular joint, ramus and body of the mandible. The flap was then closed with sutures. Dental implants can be placed once the grafts have fully integrated with the reconstructed jaw.
The patient and her parents were very satisfied with the results of the surgery and expressed their gratitude before final discharge from the hospital. Instructions were given to the parents to return to the hospital in 3-4 years for a radiographic checkup of the reconstructed jaw joint.