Analysis of postsurgical neurologic alteration in the trigeminal nerve.

Neurologic alteration in 36 patients who had received either a sagittal split osteotomy, an intraoral vertical ramus osteotomy, or a mandibular vestibuloplasty was evaluated by questionnaire, detailed neurosensory examination, and personality testing. Subjective sensory alteration was reported by 69.4% of the entire group; neurosensory examination showed demonstrable neuropathy in 54% of the 72 nerve divisions that were examined, with the greatest incidence, 84.6%, in the group that had received sagittal split osteotomies. Personality testing indicated that dysesthetic patients experienced greater degrees of neuroticism and depression than did patients without pain.     

Relationship of the mandibular canal to the lateral cortex of the mandibular ramus as a factor in the development of neurosensory disturbance after bilateral sagittal split osteotomy.

PURPOSE: This study evaluated the location of the mandibular canal in the ramus of the mandible before bilateral sagittal split ramus osteotomy and examined its relationship with postoperative neurosensory disturbance. PATIENTS AND METHODS: The subjects consisted of 20 patients undergoing bilateral sagittal split ramus osteotomy. Before surgery, the region from a plane containing the lowest point of the mandibular foramen to 22 mm below it was observed on transaxial computed tomograms acquired with a slice thickness of 2 mm and a slice interval of 2 mm. The relationship between the distance from the mandibular canal to the external cortical bone and neurosensory disturbance in the lower lip or mentum more than 1 year after surgery was evaluated. RESULTS: The mandibular canal came into contact with the external cortical bone on 10 sides (25%); neurosensory disturbance occurred on all these sides, an incidence significantly greater than that (20%) on the 30 sides (75%) without contact between the canal and the external cortical bone (P <.05). In patients with mandibular canal/external cortical bone contact, the vertical extent of contact ranged from 2 to 18 mm (mean, 10.6 +/- 4.9 mm). Neurosensory disturbance was significantly more likely to be present 1 year after surgery, when the width of the marrow space between the mandibular canal and the external cortical bone was 0.8 mm or less (P <.002). CONCLUSIONS: The increased risk of neurosensory disturbance associated when there is contact between the mandibular canal and the external cortical bone should be considered when sagittal split ramus osteotomy is performed.     

Neurosensory disturbances one year after bilateral sagittal split mandibular ramus osteotomy performed with separators.

BACKGROUND: The most frequently performed osteotomy for correction of mandibular retrognathia is a bilateral sagittal split ramus osteotomy. Permanent neurosensory disturbance of the inferior alveolar nerve is one of the most frequently and severe complications. Many authors have reported this, but the incidence differs widely. In the recent literature, only four authors have reported a percentage of less than 10% after 1 year follow-up. OBJECTIVE: To determine the incidence of permanent neurosensory disturbance of the inferior alveolar nerve after bilateral sagittal split ramus osteotomy, and possible influences of the technique used. PATIENTS AND METHODS: A series of 109 patients is reported who underwent a bilateral sagittal split mandibular ramus osteotomy with the use of separators and without the use of chisels. The segments were hold by rigid transbuccal screw fixation. RESULTS: The incidence of neurosensory disturbances 1 year after surgery was 8.3%. CONCLUSION: The use of sagittal split separators without the use of chisels, may play an important role in the relatively low percentage of persistent hypoaesthesia of the inferior alveolar nerve.     

Neurosensory alterations of the inferior alveolar and mental nerve after genioplasty alone or associated with sagittal osteotomy of the mandibular ramus.

AIMS: The purpose of our protocol is to study neurosensory disturbances following genioplasty, sagittal split mandibular osteotomy, or both procedures in combination. Many authors assessed the incidence and degree of neurosensory disturbances of the inferior alveolar nerve following orthognathic surgery but often results are difficult to interpret and compare due to a lack of standardization of methods. PATIENTS: Fifty patients (24 males and 26 females) were tested with qualitative (touch sensation, sharp/blunt test, cold sensation and hot sensation) and quantitative methods (localization test, two point static and dynamic test) at least 1 year after orthognathic surgery. The patients were divided into the following groups: 10 patients in group 1 (controls); 12 patients in group 2 (genioplasty alone or in association with maxillary osteotomy or vertical mandibular ramus osteotomy); 10 patients in group 3 (sagittal split osteotomy alone); 18 patients in group 4 (sagittal split osteotomy with concomitant genioplasty). METHOD: On both sides four areas were tested: centre of chin and lip (cutaneous and mucosal sides), 2 cm lateral to the chin centre (cutaneous and mucosal sides), 3 cm lateral to the chin centre i.e. approximately at the mental foramen (cutaneous and mucosal sides) and vermilion. Tests were always performed by the same person. All patients were also asked to indicate whether the altered sensation was considered subjectively as being disabling. RESULTS: None of the patients showed persistent anaesthesia in the tested areas according to the qualitative tests. In group 2 the quantitative sensory tests revealed normal or slight hypoaesthesia (17%) in all areas tested; in 30% of the patients of group 3, minimal quantitative sensory disturbances were noted, while the incidence of objective sensory deficits increased in patients who had undergone a concomitant genioplasty (40% among group 4). Among the tested areas the vermilion and oral commissure were affected most often in all groups. Statistical analysis (using STATA 6.0) revealed that these differences were significant (p<0.05). There were also significant differences between group 1 and groups 3 and 4 for tactile sensitivity, location tests and sharp-blunt discrimination, while two point discrimination (quantitative test) showed statistically significant differences between group 1 and all other groups (2-4). No statistically significant differences among the four groups were found for thermal sensation (hot and cold). CONCLUSIONS: The combination of genioplasty and sagittal split osteotomy seems to be more detrimental for the lip sensibility than genioplasty or sagittal split alone. Thermal sensation is less affected than tactile sensation, location and two point discrimination tests (static and dynamic). Despite that, sensory deficit was never considered as disabling by the patients subjectively.     

Long-term neurosensory deficits following transoral vertical ramus and sagittal split osteotomies for mandibular prognathism

Twenty-six patients who had been treated for mandibular prognathism by either bilateral sagittal split osteotomy or transoral vertical ramus osteotomy were evaluated by neurosensory examination. Neuropathy was demonstrable in 28.8% of the 52 mental nerves examined. The incidence of neuropathy was significantly higher in the bilateral sagittal split osteotomy group than in the transoral vertical osteotomy group.     

The effect of physical rehabilitation on mandibular function after ramus osteotomies

The efficacy of a systematic regimen of rehabilitation of mandibular function after ramus osteotomy was investigated. Forty-eight patients who had had either sagittal split ramus osteotomy to advance the mandible or intraoral vertical ramus osteotomy to retract the mandible were studied; 24 patients received rehabilitation and 24 did not. Pre- and postsurgical maximal mandibular opening, lateral and protrusive mandibular movements, maximum bite force, muscle fatigability, and clinical evaluation of the temporomandibular joints were compared between the two groups. Patients who underwent an intraoral vertical ramus osteotomy did not show a significant decrease in any of the parameters measured whether or not rehabilitation was used. However, patients who underwent sagittal split ramus osteotomies without subsequent rehabilitation had significant decreases (P less than 0.05) in mean mandibular opening and bite force as well as increases (P less than 0.05) in muscular fatigability compared with patients who underwent rehabilitation. These findings indicate the need for routine preoperative evaluation of mandibular and temporomandibular joint function and postsurgical physical rehabilitation after ramus osteotomies.     

Incidence of neurosensory disturbance after sagittal split osteotomy alone or combined with genioplasty

We mailed questionnaires to all patients who had had sagittal split osteotomies alone (n= 84) or in combination with genioplasty (n = 37) between 1995 and 2000, to find out the incidence of postoperative sensory disturbances. The patients with sagittal split osteotomies alone reported sensory disturbance in 48/131 (37%) operated sides. When combined with genioplasty patients experienced them in 20/54 (37%) operated sides. The incidences were 36/101 (36%) for mandibular advancement and 12/30 (40%) for mandibular setback. Out of the patients with sagittal split osteotomies alone, 59/66 (89%) were satisfied with the result of the operation, and when combined with the genioplasty the corresponding figure was 23/27 (85%). We conclude that differences in the incidence of sensory disturbance after sagittal split osteotomy for mandibular advancement and setback were not significant. The combination with genioplasty did not increase the incidence of sensory disturbance. Sensory changes after the osteotomies do not serve to be the main determinant of the patients' satisfaction.     

下颌前突畸形的正颌外科矫治

目的 总结正颌外科矫治下颌前突畸形的临床经验。方法 对32例下颌前突畸形患者进行了正颌外科手术，其中12例行双侧SSRO，4例行双侧IORO，10例行双侧IVRO，5例行上下颌前部根尖下截骨，1例行下颌骨体部截骨，同期搭配施行水平截骨颏成形术12例，畸形涉及上颌骨行LeFortⅠ型截骨9例。结果 32例下颌前突畸形患者术后外观及功能均获得满意效果。并发症有术后下颌前突轻度复发4例，明显复发1例，下颌骨升支骨折一侧1例，下牙槽神经一侧断离1例，结论 随访结果显示应用IVRO，SSRO等术式治疗下颌前突畸形只要术式选择及操作得当，能获得较满意效果。文中就手术方法，注意事项及并发症等进行了讨论。     

A new osteotomy for the correction of mandibular prognathism: techniques and rationale of the intraoral vertico-sagittal ramus osteotomy.

The sagittal split ramus osteotomy (SSRO) and the intraoral vertical ramus osteotomy (IVRO) are long established methods for correcting mandibular prognathism, each having its own advantages. However, both procedures have the same disadvantage: the potential for postoperative condylar displacement. The displacement of the condyle is mainly due to the fact that the osteotomy plane is not parallel to the original sagittal plane in which the mandible is repositioned. The author has developed a new ramus osteotomy since 1985 in which the osteotomy plane is theoretically parallel to the original sagittal plane and thereby attempting to decrease the incidence of condylar displacement. This osteotomy was designed additionally to decrease neurosensory disturbances and has the advantages of both methods, and therefore has been named 'intraoral vertico-sagittal ramus osteotomy (IVSRO)'. Initial experience with the 24 prognathic patients operated on by means of the IVSRO indicated excellent clinical results. It has been noted clinically that the IVSRO is very effective in reducing postoperative iatrogenic TMJ symptoms and in treating preoperative TMJ symptoms. It has the additional effect of reducing neurosensory disturbances. This osteotomy seems to be more applicable in mandibular prognathism with excessive flaring of the ramus, particularly that associated with TMJ dysfunction, because the IVSRO has a 'condylotomy effect' and its splitting plane diverges less from the original sagittal plane than that of the SSRO and the IVRO.     

Evaluation of risk of injury to the inferior alveolar nerve with classical sagittal split osteotomy technique and proposed alternative surgical techniques using computer-assisted surgery

Neurosensory disturbance after sagittal split osteotomy is a common complication. This study evaluated the course of the mandibular canal at three positions using computed tomography (CT), assessed the risk of injury to the inferior alveolar nerve in classical sagittal split osteotomy, based on the proximity of the mandibular canal to the external cortical bone, and proposed alternative surgical techniques using computer-assisted surgery. CT data from 102 mandibular rami were evaluated. At each position, the distance between the mandibular canal and the inner surface of the cortical bone was measured; if less than 1mm or if the canal contacted the external cortical bone it was registered as a possible neurosensory compromising proximity. The course of each mandibular canal was allocated to a neurosensory risk or a non-neurosensory risk group. The mandibular canal was in contact with, or within 1mm of, the lingual cortex in most positions along its course. Neurosensory compromising proximity of the mandibular canal was observed in about 60% of sagittal split ramus osteotomy sites examined. For this group, modified classic osteotomy or complete individualized osteotomy is proposed, depending on the position at which the mandibular canal was at risk; they may be accomplished with computer-assisted navigation.     

Sensory impairment following sagittal split osteotomy for correction of mandibular retrognathism.

Sagittal split osteotomy of the mandibular ramus is performed in close proximity to the inferior alveolar nerve and may result in postoperative neurosensory disturbances. Intraoperative strain on the nerve and other complications in 25 patients undergoing bilateral sagittal split osteotomy were recorded. Neurosensory testing was carried out before and after surgery. The patients reported sensory disturbances in 54% of sites 4 days postoperatively and 42% and 34% of sites at 9 weeks and 6 months, respectively. Objective assessments showed an incidence of 34% at 4 days, 20% at 9 weeks, and 8% at 6 months. Sensory disturbance was closely related to the degree of intraoperative strain on the nerve.     

Three-dimensional computed tomography evaluation of postsurgical condylar displacement after mandibular osteotomy

Objective. The purpose of this study was to examine both condylar displacement of the temporomandibular joint after sagittal split ramus osteotomy with rigid osteosynthesis and intraoral vertical ramus osteotomy without osteosynthesis in patients with mandibular prognathism by means of three-dimensional computed tomography.Study design. In this pilot study, five patients treated with sagittal split ramus osteotomy and 5 patients treated with intraoral vertical ramus osteotomy were evaluated. A technique to superimpose a postoperative three-dimensional computed tomography image on its corresponding preoperative image was designed. Postoperative condylar displacement, rotation, and tilting were measured in three-dimensional computed tomography images.Results. Within 3 to 6 months after surgery, changes in the inclination of the condylar axes were distinctly seen, although changes in the position of the condyles within the joints were minimal. In particular, outward rotation of the condylar long axes after intraoral vertical ramus osteotomy was a frequent finding.Conclusions. The three-dimensional computed tomography superimposition technique was a practical method of evaluating post-surgical condylar displacement after mandibular osteotomy.     

Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients' records

This retrospective study aimed at evaluating the long-term incidence of neurosensory disturbance (NSD) after sagittal split osteotomy (SSO) and intraoral vertical ramus osteotomy (IVRO). Furthermore, a comparison was made between the results obtained by questionnaires and information in the patient records in the evaluation of nerve function. Finally, the degree of discomfort caused by the NSD was evaluated. One hundred and twenty-nine patients, who underwent IVRO (79 patients) and SSO (50 patients), were included. Questionnaires were mailed to the patients at least one year after the operation. The records of all patients, who returned the questionnaires, were reviewed. The results of NSD obtained by questionnaires and records differed indicating a disagreement between the judgement of the surgeon and the patient's opinion. Long lasting NSD was underestimated by the surgeon as compared to the patient's subjective symptom. Long lasting NSD was reported in 7.5% (questionnaire), 3.8% (record) after IVRO and in 11.6% (questionnaire) and 8.1% (record) after SSO.     

Comparison of the quality of life changes of patients receiving sagittal split ramus osteotomy or intraoral vertical subsigmoid osteotomy for mandibular prognathism

Clinical Oral Investigations - To investigate and compare the effect of two orthognathic procedures for mandibular setback, namely, sagittal split ramus osteotomy (SSRO) and intraoral vertical...     

双侧下颌骨升支矢状劈开截骨术治疗下颌前突畸形

目的探讨口内进路双侧下颌骨升支矢状劈开截骨后退小钛板内固定治疗重度下颌前突畸形的临床疗效。方法9例上颌骨发育正常、下颌骨真性前突、严重反He关系的患者，行术前牙齿正畸治疗后，采用口内进路双侧下颌骨升支矢状劈开截骨后退小钛板内固定，术后正畸治疗，恢复尖窝咬He关系。结果所有病例均取得满意的疗效，获得协调的上下颌骨关系，术后随访1年，未见下颌前突复发。结论重度下颌前突畸形采用口内进路双侧下颌骨升支矢状劈开截骨术及正畸治疗是有效的，值得临床推广应用。     

髁突骨软骨瘤的正颌外科治疗

目的 探讨正颌外科技术在髁突骨软骨瘤治疗中的应用效果。方法 利用正颌外科方法治疗12例髁突骨软骨瘤患者,进行Le Fort Ⅰ型截骨术修正上颌骨,采用口内入路患侧升支垂直截骨术切除病变髁突,健侧行升支矢状切开术及颏成形术矫正咬合及偏斜。结果 12例患者术后面型均得到矫正,随访2年以上无1例复发。结论 利用正颌外科技术治疗髁突骨软骨瘤,可以避免常规口外切口面部留有的瘢痕,并在切除肿瘤的同时矫正了面型。     

Stability of the Le Fort I osteotomy with anterior internal fixation alone: a case series.

PURPOSE: The purpose of this case series was to evaluate the late postsurgical stability of the Le Fort I osteotomy with anterior internal fixation alone and no posterior zygomaticomaxillary buttress internal fixation. PATIENTS AND METHODS: Sixty patients with maxillary vertical hyperplasia and mandibular retrognathia underwent a 1-piece Le Fort I osteotomy of the maxilla with superior repositioning and advancement or setback. A bilateral sagittal split ramus osteotomy for mandibular advancement was also performed in 22 patients. Stabilization of each maxillary osteotomy was achieved using transosseous stainless steel wires and/or 3-hole titanium miniplates in the piriform aperture region bilaterally, with no zygomaticomaxillary buttress internal fixation. (Twelve of the 60 identified patients were available for a late postoperative radiographic evaluation.) Lateral cephalometric radiographs were taken preoperatively (T1), early postoperatively (T2), and late postoperatively (T3) to analyze skeletal movement. RESULTS: These 12 patients (5 male, 7 female) had a mean age of 24.5 years at surgery. Mean time from surgery to T2 was 41.2 days; mean time from surgery to T3 was 14.8 months. One patient received anterior wire osteosynthesis fixation, while 11 patients received both anterior titanium miniplate internal skeletal fixation and anterior wire osteosynthesis fixation. Six patients underwent Le Fort I osteotomy with genioplasty, 1 patient underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy, and 5 patients underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy and genioplasty. These 12 patients all underwent maxillary superior repositioning with either advancement (11 patients) or setback (1 patient). Statistically significant surgical (T2-T1) changes were found in all variables measured. In late postsurgical measurements (T3-T2), all landmarks in the horizontal and vertical plane showed statistically significant skeletal stability. CONCLUSION: This case series suggests that anterior internal fixation alone in cases of 1-piece Le Fort I maxillary superior repositioning with advancement has good late postoperative skeletal stability.     

Impairment of the inferior alveolar nerve after sagittal split osteotomy

The incidence and degree of neurosensory disturbance of the inferior alveolar nerve, as well as its recovery course, were studied on 46 sides in 23 patients who had undergone bilateral sagittal split osteotomies, by means of subjective symptoms, light touch, anaesthesiometer and two-point discrimination. The degree of disturbance was classified into mild, moderate and severe grades by the threshold pressure shown in tests with the anaesthesiometer. The disturbance, which was almost exclusively limited to mild (37%) and severe (28%) grades, was observed in 67% of the sample at one week. The disturbance disappeared completely within one to three months postoperatively in most sites with mild disturbance, and within three months to one year in half of the severely affected sites. Although the recovery was delayed in the other half of the severely disturbed sites, the disturbance was of mild grade at one and a half years. The overall incidence of disturbance at one year was 15%. Computed tomographic examination of the ascending ramus showed that the narrowest width between the mandibular canal and the buccal cortical plate ranged from 0 mm to 3.2 mm with a mean of 1.6 +/- 0.9 mm (SD) and it was less than 1.2 mm in 91% of sites with a severe grade disturbance, whereas it was distributed in a range of 0.9 mm to 3.2 mm in sites with no disturbance or with mild or moderate disturbance. The importance of preoperative computed tomography to indicate the location of the mandibular canal and the use of a thin cement spatula for the osteotomy was stressed, to avoid or reduce postoperative development of neurosensory impairment.     

Patterns of lingual split and lateral bone cut end and their associations with neurosensory disturbance after bilateral sagittal split osteotomy

The purpose of this study was to characterize the patterns of lingual split and lateral bone cut end (LBCE) after bilateral sagittal split osteotomy (BSSO) in patients and identify their associations with postoperative neurosensory disturbance. This retrospective cohort study recruited 273 patients with skeletal malocclusion who received BSSO. The postoperative cone beam computed tomography data were reconstructed to three-dimensionally view the patterns of lingual split and LBCE. Associations between lingual split and LBCE and their effects on neurosensory disturbance in the lower lip and chin were determined. Six types of lingual split and three types of LBCE were defined based on three-dimensional images. Type I lingual split as a vertical fracture line to the inferior mandibular border was the most common (40.29%). Inferior LBCE was the most prevalent, followed by lingual and buccal types. Significant associations among lingual split, LBCE and skeletal deformities were found (P < 0.05). However, patterns of lingual split and LBCE were not associated with the incidence of neurosensory disturbance. Patterns of lingual split after BSSO significantly associated with types of LBCE and dentomaxillofacial deformities, but not with postoperative neurosensory disturbance.     

口内路径下颌骨升枝矢状劈开截骨术治疗下颌前突畸形

下颌骨升枝矢状劈开术是目前世界上使用最普遍的矫正下颌骨畸形的手术方法之一。作者采用口内入路下颌骨畸形的手术方法之一。作者采用口内入路下颌骨升枝矢状劈开截骨术治疗下颌骨前突１８２例，其中真性下颌前突１４３例，假性下颌前突３９例。年龄在１５～５８岁之间，平均２４岁。随访６个月～９年。除９例术后畸形复发需再次矫正以外均获满意效果。本文介绍了口内入路下颌骨升枝矢状截骨术的手术过程及注意事项，并着重讨论了其优缺点，可能出现的并发症及处理方法