3. Discussion and Conclusions
Morphological changes in the upper respiratory tract and pharynx occur
due to morphological changes and position movements of the mandible due
to correction surgery, and changes in respiratory physiology are
observed [9]. Therefore, in Europe and the United States, one of the
treatment methods for OSA is corrective surgery such as simultaneous
upper and lower jawbone movement and genioglossus/anterior traction of
the tongue muscle group, and its usefulness has also been reported
[10]; however, it is not yet common in Japan. In our literature
search, we found that LF+HS and MDO and GP were performed on patients
with mandibular condyle who had resorption changes in the mandibular
condyle, as in the present case, and had OSA. Consequently, mandibular
and malocclusion failures occur. In addition, there are no reports on
improvements in OSA.
Regarding the selection of technique: Regarding the maxillary procedure,
LF has a limited amount of upward movement of the maxilla, but when HS
is used in combination with LF, it is possible to move the maxillary
bone fragment significantly upward. As it has been reported that LF+HS
is indicated for cases with an upward movement of ≥4 mm [11], in the
present case, the maxillary alveolar bone fragment was used for
maxillary molars measuring 5 mm and anterior teeth measuring 7 mm. The
mandibular movement was secured by raising it counterclockwise.
Regarding the mandibular procedure, PCR is one of the complications
after anterior mandibular movement by SSRO, and its incidence has been
reported to be from 4.5% to 21% [12, 13]. In contrast, compared
with SSRO, MDO can avoid the generation of tension and overloading of
mandibular condyle due to the rapid extension of soft tissue caused by
surgical procedures and blood flow to the mandibular condyle due to
minimal periosteal detachment. Several reports [5, 14] indicate that
it is more suitable than SSRO as a treatment method considering PCR
because it can maintain the blood flow. In particular, Strijen et al.
mentioned that the one-time anterior movement of the mandible by SSRO
causes heavy burden on the mandibular condyle, and as a result of slow
anterior extension of the mandible by MDO in 40 patients with PCR, we
have reported the usefulness of MDO for these patients, describing that
PCR was not observed in 39 of those patients (97.5%)[15].
Therefore, in the present case, in which an absorption image was
observed in the mandibular condyle before surgery, MDO was selected to
prevent the enhancement of PCR.
PCR: The distance from the mandibular condyle to the mandibular notch
was measured using 3D-CT images obtained preoperatively March 7, 2013)
and 1 year and 3 months after LF+HS and MDO (August 14, 2014). Comparing
the distances, the right side decreased by 0.4 mm from 12.5 to 12.1 mm,
and the left side decreased by 1.6 mm from 8.3 to 6.7 mm. In other
words, the right side was almost the same as before the operation, but
the left side demonstrated mild bone resorption.
Sato et al. stated that follow-up is important for at least 2 years, as
bone changes in PCR can last for more than 1 year after surgery
[16]. We also planned a long-term follow-up, and because of the
difficulty to assess PCR from the cephalometric profile image alone, we
planned to follow up with CT images, especially 3D-CD images, in
addition to the cephalometric profile image. However, although the
cephalometric profile image could be tracked until Nov 17, 2015 (LF+HS,
2 years and 6 months after MDO) just before the patient moved to a
distant place, CT imaging was obtained at good timing. However, we were
reluctant to complete the examination without realizing it.
Relapse: Regarding relapse, McCarthy et al. reported a rate of 22% and
Miyamoto et al. reported a rate of 30%–40% relapse [6,7]. To
evaluate the relapse in the present case, we modified the method
described by Miyamoto et al. to measure the distance between the left
and right Condylion-B points in the cephalometric side view image
[7]. As a result, when the time points immediately after LF+HS and
MDO surgery and 2 years and 6 months after surgery were compared, 25.6%
relapse was observed on the right side and 33.0% relapse was observed
on the left side, but we considered that the upper and lower jaws were
stable because occlusal tightness was obtained by the postoperative
orthodontic treatment.
The anterior–posterior diameter of the pharynx: Comparing the posterior
part of the soft palate before surgery with that 7 months after LF+HS
and MDO (Dec 9, 2013), (1) PPS decreased from 35.1 to 34.8 mm (−0.3 mm),
and (2) SPPS decreased from 17.7 to 19.3 mm. It increased by +1.6 mm,
and (3) MPS increased from 4.6 to 10 mm (+5.4 mm).
In the posterior part of the tongue, (4) IPS increased from 7.4 to 11.2
mm (+3.8 mm), and (5) EPS increased from 6.7 to 10.3 mm (+3.6 mm). It is
considered that this finding is because the tongue tuft became larger
due to the anterior extension of the mandible by MDO, and the
anterior–posterior diameter of the pharynx behind the tongue increased
due to the anterior extension of the tongue.
Regarding the position of the hyoid bone: Comparing preoperative values
and those measured 7 months after LF+HS and MDO (Nov 6, 2013), it was
observed that (6) S-H decreased from 106.4 to 104.4 mm (−2.0 mm), and
(7) C3-H decreased from 42.7 to 48.2. It increased to mm (+5.5 mm), and
the hyoid bone moved upward and anteriorly. It is speculated that this
is because the hyoid muscles and geniohyoid muscles attached to the
hyoid bone and geniohyoid spines were pulled upward and anteriorly by
the MDO, and the hyoid bones to which these muscles were attached moved
upward and anteriorly. Moreover, the AHI measured 5 months after LF+HS
and MDO (Oct 10, 2013) decreased from 22.5 to 9.8/h, and the ESS score
decreased from 14 to 2 points, which we felt were during the daytime.
The drowsiness almost disappeared.
Comparing the values measured immediately before GP (Nov 6, 2013) and
after GP (Dec 13, 2013), it was observed that (4) IPS behind the tongue
increased from 11.2 to 11.8 mm (+0.6 mm), and (5) EPS increased from
10.3 to 8.6. It decreased to (−1.7 mm). In other words, no significant
change was observed in the anterior–posterior diameter of the pharynx
behind the tongue depending on the GP. However, the AHI before and after
GP decreased from 9.8 to 7.8/h, and daytime sleepiness disappeared
completely. Tonogi et al. reported that when the pharynx was observed
using an endoscope after SSRO, the pharynx expanded not only in the
anterior–posterior diameter but also in the left–right diameter
[17]. In the present case, MDO was performed instead of SSRO, but as
reported by Tonogi et al., the changes in the size of pharynx after MDO
are not limited to the anterior–posterior diameter of the cephalometric
profile image but will be affected by result of endoscopy and CT in the
future. It was suggested that the change in diameter should be measured
and examined.
Comparing the values of (6) S-H and (7) C3-H, which indicate the
position of the hyoid bone, immediately before GP (Nov 6, 2013) and 1
week after GP (Dec 13, 2013), (6) S-H was 104.4 mm. It increased from
107.8 mm (+3.4 mm), and (7) C3-H decreased from 48.2 to 46.5 mm (−1.7
mm). Since GP pulls the genioglossus muscle and geniohyoid muscle
attached to the genioglossus anteriorly, it is considered that the hyoid
bone moves upward and anteriorly after GP. However, as indicated by
Shimamine et al., MDO performed before GP caused the infrahyoid muscles
that had once stretched to contract again as the anterior movement of
the mandible caused the tongue to expand forward[8]. Therefore, (5)
EPS decreased, and it was considered that the force to move the hyoid
bone downward was exerted.
The increase in pharyngeal anterior–posterior diameter before surgery,
after LF+HS and MDO and after GP, was the largest in (1) PPS (+6.1 mm).
This result and AHI, which was 22.5/h at the first visit, decreased
significantly to 7.8/h after all surgeries (LF+HS and MDO and GP), and
daytime sleepiness disappeared completely as a clinical symptom.
Therefore, it was speculated that the site of obstruction in the present
case was the posterior part of the soft palate, especially (1) PPS.
Isono reported that among the 124 patients with OSA who underwent
general anesthesia hypopharyngeal endoscopy, 111 patients whose
obstruction pressure was above the atmosphere were examined, and the
obstruction site was found to be the soft palate. The number of patients
was 54% [18].
After LF+HS and MDO surgery, drowsiness did not appear during the
daytime, and fortunately, in the present case, the corrective surgery
was able to improve both small mandibular disease and OSA. However, the
criteria for adaptation and the prediction of improvement in symptoms
associated with jawbone movement are not yet sufficient. Especially,
Takehiro et al. report that it is necessary to consider the balance
between the amount of change in soft tissues and the size of bone around
the soft tissue for the mechanism of OSA onset [19]; also, it is
necessary to consider that not only changes in bone movement but also
neural regulatory mechanisms by orthognatic surgery are involved.
Moreover, it is necessary to evaluate the size of soft tissues such as
the tongue and soft palate and analyze the functional changes, and we
believe that elucidation of these aspects will be the future task.