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Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients’ records
Int. J. Oral Maxillofac. Surg. 2005; 34: 247–251 doi:10.1016/j.ijom.2004.06.009, available online at http://www.sciencedirect.com
Clinical Paper Orthognathic Surgery
Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients’ records
A. Al-Bishri1, Z. Barghash2, J. Rosenquist1, B. Sunzel1 1 Department of Maxillofacial Surgery, University Hospital MAS, Malmo¨, Sweden; 2 Folktandvard Nyhem, Halmstad, Sweden
A. Al-Bishri, Z. Barghash, J. Rosenquist, B. Sunzel:Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients’ records. Int. J. Oral Maxillofac. Surg. 2005; 34: 247–251. # 2004 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. 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.
The most common surgical procedures for correction of mandibular deformities are the sagittal split (SSO) and intraoral vertical ramus osteotomies (IVRO). SSO was described by SCHUCHARDT in 194219, and later modified by TRAUNER & OBWEGESER in 195722. Since then various modifications1,5,8 have been added to assure good bone healing, avoid unfavourable fracture, eliminate the need 0901-5027/030247+05 $30.00/0
for postoperative intermaxillary fixation (IMF) and decrease the incidence of neurosensory disturbance (NSD). The need for postoperative IMF was eliminated by the introduction of internal rigid fixation. NSD after SSO remains the main drawback of this operation with an incidence ranging from 9%14 to 84.6% objectively and 100% subjectively23.
Key words: sagittal split osteotomy; intraoral vertical ramus osteotomy; neurosensory disturbance; inferior alveolar nerve injury. Accepted for publication 8 June 2004
The vertical ramus osteotomy was described first as an extraoral procedure by LIMBERG13 in 1925 and later by CALD2 WELL & LETTERMAN in 1954. The main disadvantages were extraorally visible scars, condylar sag, necrosis of the distal tip of the proximal segment and the need for postoperative IMF. MOOSE15 in 1964 overcame the disadvantage of the facial scar by introducing an intraoral
# 2004 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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approach. HALL & MCKENNA in 19877 advised that a portion of the medial pterygoid muscle should remain attached to the distal tip of the proximal segment in order to eliminate the disadvantages of condylar sag and ischemic necrosis of the distal tip of the proximal segment. Postoperative IMF is still the main drawback of the intraoral vertical ramus osteotomy (IVRO). The main advantage of the IVRO over the SSO is the comparatively low incidence of NSD that ranges from 0%25 to 35%23. The higher incidence of NSD after SSO can be explained by more technical difficulties and closer proximity to the nerve during the operation compared to the IVRO. Injuries to the inferior alveolar nerve during SSO may occur due to stretching of the nerve during medial retraction, adherence of the nerve to the proximal segment after splitting, direct manipulation of the nerve, bony roughness on the medial side of the proximal segment or segment mobilization20. Osteosynthesis may induce injuries to the inferior alveolar nerve by compression of the nerve during fixation or by direct injury to the nerve. Severance of the nerve may also occur during osteotomy procedure. In IVRO, nerve injury could occur if the osteotomy line is too close to the mandibular foramen. This is a concern particularly if the surgeon wants a long proximal segment. Accidental medial movement of the proximal segment after the osteotomy could also contribute to nerve injury. The aims of this study were to evaluate NSD after SSO and IVRO, asses the difference between questionnaire and patient’s record in evaluating of the NSD and evaluate the discomfort caused by NSD after SSO and IVRO.
female and 23 male) and 43 from the SSO patients (27 female and 16 male). Patients were queried about perceived sensory change along the distribution of the lingual and/or inferior alveolar nerves after the operation, duration of these changes, the effect of the changes on their life, and their satisfaction with the result of the operation. A visual analogue scale (VAS) graded from 0 (no discomfort) to 10 (intolerable discomfort) was included for the evaluation (see the questionnaire form). To evaluate the effect of the NSD on the patients, the grades of the VAS were interpreted as follows: 0–2 mild discomfort, 2–4 mild to moderate discomfort, 4–6 moderate discomfort, 6–8 moderate to severe discomfort, and 8–10 severe discomfort. A contact telephone number was provided for any further questions and a stamped addressed envelope was included for the return of the questionnaire. The records of all patients who returned the questionnaire were reviewed to identify any reported NSD after the operation. In our department, all patients are routinely followed up to18 months after the operation. During the 18 months follow up the NSD was always tested subjectively by asking the patients and objectively by using a dental probe to assess the sensory changes along the distribution of the mental nerve (lower lip and chin). All patients went through the same sequence of pre- and postoperative orthodontic treatment, treatment planning, surgical treatment and follow up. Cephalometric radiographs were taken preoperatively, immediately postoperatively, immediately after the release of intermaxillary fixation (IVRO), 6 months and 18 months postoperatively.
Material and methods
Surgical procedure
One hundred and twenty-nine patients who underwent bilateral IVRO (79 patients, 42 females and 37 males) and bilateral SSO (50 patients, 31 females and 19 males) between 1995 and 1999 at the department of Maxillofacial Surgery, University Hospital MAS, Malmo¨ , Sweden, were included in this study. The age of the patients ranged between 15 and 58 years with an average of 36.5 years. Questionnaires were mailed to the patients at least one year after the operation. Ninety-six completed questionnaires (74%) were returned, 53 questionnaires from the IVRO patients (30
In preparation for surgery under general anaesthesia, a local anaesthetic, mepivacain with adrenaline (5 mg/ml þ 5 mg/ ml; Carbocain-adrenalin, Astra-Zeneca, Sweden), was infiltrated in the operating area. Antibiotics and cortisone were routinely administered to all patients during
the first 24 h (benzyl penicillin 3 g 3 or clindamycin 600 mg 3 in case of penicillin allergy and 4 mg betamethasone 4) starting immediately before the operation. To avoid postoperative swelling of the lower lip and abrasion of the corner of the mouth a steroid cream was frequently used throughout the operation. The surgical technique for both sagittal split osteotomy and vertical ramus osteotomy were performed as described by TERRY & WHITE21. Intermaxillary fixation of the IVRO was achieved by using orthodontic brackets and stainless steel wires (0.4 mm). The wound was sutured with 4-0 Vicryl. All patients were kept on intermaxillary fixation for 4–6 weeks postoperatively. In the SSO the final fixation on each side was achieved with two or three bicortical positional screws through a transbuccal approach. No intermaxillary fixation was used postoperativly with the exception of guiding elastics. Results Intraoral vertical ramus osteotomy
Questionnaires Fifty-three completed questionnaires representing 106 operated sides were returned and analyzed. The returned questionnaires reported immediate NSD after IVRO in 11 operated sides (10.4%); three of them regained full sensibility during the first year whereas eight (7.5%) sides had long lasting NSD. In one of the patients, the NSD was bilateral (Table 1). Four patients out of seven (57%) with long lasting NSD described the effect of the disturbance as mild (Fig. 2). Ninety-eight percent of the patients operated for IVRO were satisfied with the result of the operation. The only patient, who was dissatisfied, did not have any long lasting NSD after the operation.
Record review In the files of the 53 patients with 106 operated sides, who returned completed
Table 1. NSD after IVRO and SSO as reported in returned questionnaires and patients record Record review Operation IVRO SSO
Questionnaires
Total sides
Immediate
Long lasting
Immediate
Long lasting
106 86
8 33
4 7
11 25
8 10
Neurosensory disturbance after sagittal split
249
immediate NSD in 33 operated sides (38.4%). Twenty-six of the affected sides regained full sensibility during the first postoperative year; thus seven operated sides (8.1%) remained with long lasting NSD (Fig. 1). Discussion
Fig. 1. The difference between immediate and long lasting NSD in both record review (RR) and questionnaire (Q).
questionnaires, immediate NSD was recorded in eight operated sides (7.5%). Four of them regained full sensibility over a period of one year, leaving four sides (3.8%) with long lasting NSD (Fig. 1). Sagittal split osteotomy
Questionnaires Questionnaires were returned from 43 patients with 86 operated sides. Immediate NSD was reported in 25 operated sides (29%), 15 sides regained full sen-
sibility after one year while the remaining 10 sides (11.6%) continued to have long lasting NSD. Fifty percent of the patients with NSD after SSO described the effect of NSD as mild to moderate (Fig. 2). Four out of the 43 patients (9%) were not satisfied with the result of the operation but only one attributed the dissatisfaction to sensory impairment.
Record review Reviewing of the 43 patients, who returned the questionnaires, showed
Fig. 2. Patients discomfort after SSO and IVRO according to the questionnaire.
The evaluation of NSD along the distribution of the inferior alveolar nerve (chin and lower lip) can be performed by either purely subjective (questionnaires), relatively objective (static light touch, brush directional discrimination, two-point discrimination, and thermal discrimination) and purely objective (trigeminal somatosensory evoked potentials (TSEP)16, sensory nerve action potential (SNAP)9, and blink reflex (BR)10) methods. The purely objective methods of evaluation are not easily applicable. Thus most studies depend on subjective and the relatively objective evaluation; the latter always considered by many authors as an objective evaluation. Some authors4,17,23 have shown that patients’ subjective evaluations give a higher incidence of NSD than relatively objective evaluations while others have reported the opposite12,26. A good correlation between the subjective evaluation and 2-point discrimination (objective test) has also been reported3. However, it is only the patient who experience whether his/her sensibility has been changed. Therefore, in this study we chose the subjective evaluation to assess the NSD after sagittal split osteotomy. Upon reviewing the literature one finds big differences in the armamentarium used in objective evaluation tests of NSD. This could lead to differences in the definition of NSD. Such disadvantages could be solved by standardization of the instrument used for the tests as described by GHALI & EPKER6 in 1989. The reported immediate postoperative NSD after SSO in the previous studies was high ranging from 54%17 to 100%23. The high incidence of the immediate NSD could be caused by direct manipulation of neurovascular bundle during the operation, which often becomes swollen. As the bundle is confined to a limited bony space after fixation, nerve damage (neurapraxia) could occur. Neurapraxia is an interruption in conduction of the impulse down the nerve fiber, there is no axonal degeneration and the recovery takes place without wallerian degeneration11,18. This is probably a biochemical lesion caused by
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concussion or shock-like injuries to the fiber. Compression or relatively mild, blunt blows, bring about neurapraxia. There is a temporary loss of function, which is reversible within hours to months of the injury (the average is 6–8 weeks). In our study, the record of the patients showed immediate postoperative NSD in 33 operated sides (38.4%) while the returned questionnaire showed that 25 operated sides (29%) was affected by NSD. Of those 26 of the affected sides according to the patient’s record and 15 affected side according to the questionnaire regained full sensibility during the first postoperative year. Thus long lasting NSD was present in 8.1% and 11.6% of operated side according to the patient’s record and the questionnaire, respectively. On the other hand, the immediate NSD after IVRO was reported in eight (7.5%) and 11 operated sides (10.4%) in records and questionnaires, respectively. Long lasting NSD after IVRO was 3.8% of the operated sides (four sides) in the records and 7.5% (eight sides) in the questionnaire. Our result showed higher incidence of immediate NSD after SSO in the records than in the questionnaires, while the opposite was true in the case of IVRO. This could reflect a higher concern and expectation of surgeons on NSD after SSO than after IVRO. It might also be difficult for the patients to remember a mild short NSD immediately after the operation when asked a year or more later. The absence of nerve manipulation during IVRO operation could also contribute to the lower incidence of the immediate NSD after the operation. In the case of long lasting NSD, the returned questionnaires showed higher incidence than the reviewed records for both SSO and IVRO. The higher incidence of the long lasting NSD in the questionnaire comparing to the patients records is in agreement with the results reported by PRATT et al. 199617. Our study showed a lower incidence of the long lasting NSD after IVRO compared to SSO (IVRO, 3.8% in the reviewed record and 7.5% in the returned questionnaire, SSO, 8.1% in the reviewed records and 11.6% in the returned questionnaire) these results are in agreement with the results reported previously. WALTER & GREGG23 observed that their patients subjectively complained of chronic NSD in 70% of IVRO and 100% of SSO, whereas an objective test indicated NSD in 35% of
IVRO and 84.6% of SSO operated sides. ZAYTOUN et al.27 reported no NSD after IVRO and 68% in the SSO one year after the operation. WESTERMARK et al.24 reported an incidence of NSD of 9%in the IVRO and 39.4% in the SSO. The difference in the incidence of immediate NSD after SSO and IVRO among both questionnaires and the patient’s records was significant. The NSD was described as mild in 57% of the affected patients in the IVRO group and no patient described his disturbance as moderate to severe or severe. Fifty percent (four patients) of the affected patients in the SSO describe
Appendix A.Questionnaire
the effect as moderate to severe and none of them described the effect as a severe effect, all the four patients were above the age of 40 years. This coincided with the result reported by WES25 in that the TERMARK et al. in 1999 older patients paid more attention to the NSD than the younger patients did. Regarding patient satisfaction 98% of the IVRO and 91% of the SSO patients were satisfied. The only one patient who was not satisfied in the IVRO group was not affected by NSD but due to functional reason. Out of the four patients who were not satisfied in the SSO group only one was due to NSD.
Neurosensory disturbance after sagittal split
References 1. Bell WH, Schendel SA. Biological basis for modification of the sagittal ramus split operation. J Oral Surg 1977: 35: 362–369. 2. Caldwell JB, Letterman GS. Vertical osteotomy in the mandibular rami for correction of prognathism. J Oral Surg 1954: 12: 185–202. 3. Chen N, Neal CE, Lingenbrink P, Bloomquist D, Kiyak HA. Neurosensory changes following orthognathic surgery. Int J Adult Orthod Orthognath Surg 1999: 14: 259–267. 4. Cunningham LL, Tiner BD, Clark GM, Bays RA, Keeling SD, Rugh JD. A comparison of questionnaire versus monofilament assessment of neurosensory deficit. J Oral Maxillofac Surg 1996: 54: 454–459. 5. Dal Pont G. Retromolar osteotomy for correction of prognathism. J Oral Surg Anesth Hosp Dent Serv 1961: 19: 42–47. 6. Ghali GE, Epker BN. Clinical neurosensory testing: practical applications. J Oral Maxillofac Surg 1989: 47: 1074– 1078. 7. Hall HD, McKenna SJ. Further refinement and evaluation of intraoral vertical ramus osteotomy. J Oral Maxillofac Surg 1987: 45: 684–688. 8. Hunsuck EE. A modified intraoral sagittal splitting technique for correction of mandibular prognathism. J Oral Surg 1968: 26: 249–252. 9. Ja¨a¨skela¨inen SK, Peltola JK, Forssell K, Va¨ha¨talo K. Evaluating function of the inferior alveolar nerve with repeated nerve conduction tests during
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mandibular sagittal split osteotomy. J Oral Maxillofac Surg 1995: 53: 269–279. Ja¨a¨skela¨inen SK, Peltola JK, Lehtinen R. The mental nerve blink reflex in the diagnosis of lesions of the inferior alveolar nerve following orthognathic surgery of the mandible. Br J Oral Maxillofac Surg 1996: 34: 87–95. LaBanc JP. Classification of nerve injuries. Oral Maxillofac Surg Clin North Am 1992: 4: 285–296. Leira JI, Gilhuus-Moe OT. Sensory impairment following sagittal split osteotomy for correction of mandibular retrognathia. Int J Adult Orthod Orthogn Surg 1991: 6: 161–167. Limberg AA. Treatment of open bite by means of plastic oblique osteotomy of the ascending rami of the mandible. Dent Cosmos 1925: 67: 1191–1197. MacIntosh RB. Experience with the sagittal split osteotomy of the mandibular ramus: a 13-years review. J Oral Maxillofac Surg 1981: 8: 151–165. Moose SM. Surgical correction of mandibular prognathism by intraoral subcondylar osteotomy. J Oral Surg 1964: 22: 197–201. Nakagawa K, Koichiro U, Takatsuka S, Takazakura D, Yamamoto E. Somatosensory-evoked potential to evaluate the trigeminal nerve after sagittal split osteotomy. Oral Surg Oral Med Oral Pathol 2001: 91: 146–152. Pratt CA, Tippett H, Barnard JD, Birnie DJ. Labial sensory function following sagittal split osteotomy. Br J Oral Maxillofac Surg 1996: 34: 75–81. Seddon HJ. Three types of nerve injury. Brain 1943: 66: 237.
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19. Schuchardt K. Ein Beitrag zur Chirurgischen Kieferorthopadie unter Berucksichtigung ihrer Bedeutung fur die Behandlung angeborener und erworbener Kieferdeformitaten bie Soldaten. Dtsch Zahn Mund Kieferheilkd 1942: 9: 73– 89. 20. Teerijoki-Oksa T, Ja¨a¨skela¨inen SK, Forssell K, Virtanen A, Forssell H. AN evaluation of clinical and electrophysiologic tests in nerev injury diagnosis after sagittal split osteotomy. Int J Oral Maxillofac Surg 2003: 32: 15–23. 21. TERRY BC, WHITE PR. Mandibular ramus surgery. In: Proffit, White, eds: Surgical Orthodontic Treatment. Mosby Year Book 1991: 264–274. 22. Trauner R, Obwegeser H. The surgical correction of mandibular prognathism and retrognathia with consideration of the genioplasty. Oral Surg Oral Med Oral Pathol 1957: 10: 677–689. 23. Walter JM, Gregg JM. Analysis of postsurgical neurologic alternation in trigeminal nerve. J Oral Surg 1979: 37: 410–414. 24. Westermark A, Bystedt H, Von Konow L. Inferior alveolar nerve functions after mandibular osteotomies. Br J Oral Maxillofac Surg 1998: 36: 425– 428. 25. Westermark A, Bystedt H, Von Konow L. Patient’s evaluation of the final result of sagittal split osteotomy: is it influenced by impaired sensitivity of the lower lip and chin? Int J Adult Orthod Orthognath Surg 1999: 14: 135–139. 26. Ylikontiola L, Kinnunen J, Oikarinen K. Comparison of different assessments measuring neurosensory deficit after bilateral sagittal split osteotomy. Int J Oral Maxillofac Surg 1998: 27: 417–421. 27. Zaytoun HS, Phillps C, Terry BC. Long-term neurosensory deficits following transoral vertical ramus and sagittal split osteotomies for mandibular prognathism. J Oral Maxillofac Surg 1986: 44: 193–196. Address: Awwad Al-Bishri Department of Maxillofacial Surgery Malmo¨ University Hospital (MAS) 205 02 Malmo¨ Sweden. Tel: þ46 40 333109 Fax: þ46 40 336205 E-mail : [email protected]
Clinical Paper Orthognathic Surgery
Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients’ records
A. Al-Bishri1, Z. Barghash2, J. Rosenquist1, B. Sunzel1 1 Department of Maxillofacial Surgery, University Hospital MAS, Malmo¨, Sweden; 2 Folktandvard Nyhem, Halmstad, Sweden
A. Al-Bishri, Z. Barghash, J. Rosenquist, B. Sunzel:Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients’ records. Int. J. Oral Maxillofac. Surg. 2005; 34: 247–251. # 2004 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. 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.
The most common surgical procedures for correction of mandibular deformities are the sagittal split (SSO) and intraoral vertical ramus osteotomies (IVRO). SSO was described by SCHUCHARDT in 194219, and later modified by TRAUNER & OBWEGESER in 195722. Since then various modifications1,5,8 have been added to assure good bone healing, avoid unfavourable fracture, eliminate the need 0901-5027/030247+05 $30.00/0
for postoperative intermaxillary fixation (IMF) and decrease the incidence of neurosensory disturbance (NSD). The need for postoperative IMF was eliminated by the introduction of internal rigid fixation. NSD after SSO remains the main drawback of this operation with an incidence ranging from 9%14 to 84.6% objectively and 100% subjectively23.
Key words: sagittal split osteotomy; intraoral vertical ramus osteotomy; neurosensory disturbance; inferior alveolar nerve injury. Accepted for publication 8 June 2004
The vertical ramus osteotomy was described first as an extraoral procedure by LIMBERG13 in 1925 and later by CALD2 WELL & LETTERMAN in 1954. The main disadvantages were extraorally visible scars, condylar sag, necrosis of the distal tip of the proximal segment and the need for postoperative IMF. MOOSE15 in 1964 overcame the disadvantage of the facial scar by introducing an intraoral
# 2004 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
248
Al-Bishri et al.
approach. HALL & MCKENNA in 19877 advised that a portion of the medial pterygoid muscle should remain attached to the distal tip of the proximal segment in order to eliminate the disadvantages of condylar sag and ischemic necrosis of the distal tip of the proximal segment. Postoperative IMF is still the main drawback of the intraoral vertical ramus osteotomy (IVRO). The main advantage of the IVRO over the SSO is the comparatively low incidence of NSD that ranges from 0%25 to 35%23. The higher incidence of NSD after SSO can be explained by more technical difficulties and closer proximity to the nerve during the operation compared to the IVRO. Injuries to the inferior alveolar nerve during SSO may occur due to stretching of the nerve during medial retraction, adherence of the nerve to the proximal segment after splitting, direct manipulation of the nerve, bony roughness on the medial side of the proximal segment or segment mobilization20. Osteosynthesis may induce injuries to the inferior alveolar nerve by compression of the nerve during fixation or by direct injury to the nerve. Severance of the nerve may also occur during osteotomy procedure. In IVRO, nerve injury could occur if the osteotomy line is too close to the mandibular foramen. This is a concern particularly if the surgeon wants a long proximal segment. Accidental medial movement of the proximal segment after the osteotomy could also contribute to nerve injury. The aims of this study were to evaluate NSD after SSO and IVRO, asses the difference between questionnaire and patient’s record in evaluating of the NSD and evaluate the discomfort caused by NSD after SSO and IVRO.
female and 23 male) and 43 from the SSO patients (27 female and 16 male). Patients were queried about perceived sensory change along the distribution of the lingual and/or inferior alveolar nerves after the operation, duration of these changes, the effect of the changes on their life, and their satisfaction with the result of the operation. A visual analogue scale (VAS) graded from 0 (no discomfort) to 10 (intolerable discomfort) was included for the evaluation (see the questionnaire form). To evaluate the effect of the NSD on the patients, the grades of the VAS were interpreted as follows: 0–2 mild discomfort, 2–4 mild to moderate discomfort, 4–6 moderate discomfort, 6–8 moderate to severe discomfort, and 8–10 severe discomfort. A contact telephone number was provided for any further questions and a stamped addressed envelope was included for the return of the questionnaire. The records of all patients who returned the questionnaire were reviewed to identify any reported NSD after the operation. In our department, all patients are routinely followed up to18 months after the operation. During the 18 months follow up the NSD was always tested subjectively by asking the patients and objectively by using a dental probe to assess the sensory changes along the distribution of the mental nerve (lower lip and chin). All patients went through the same sequence of pre- and postoperative orthodontic treatment, treatment planning, surgical treatment and follow up. Cephalometric radiographs were taken preoperatively, immediately postoperatively, immediately after the release of intermaxillary fixation (IVRO), 6 months and 18 months postoperatively.
Material and methods
Surgical procedure
One hundred and twenty-nine patients who underwent bilateral IVRO (79 patients, 42 females and 37 males) and bilateral SSO (50 patients, 31 females and 19 males) between 1995 and 1999 at the department of Maxillofacial Surgery, University Hospital MAS, Malmo¨ , Sweden, were included in this study. The age of the patients ranged between 15 and 58 years with an average of 36.5 years. Questionnaires were mailed to the patients at least one year after the operation. Ninety-six completed questionnaires (74%) were returned, 53 questionnaires from the IVRO patients (30
In preparation for surgery under general anaesthesia, a local anaesthetic, mepivacain with adrenaline (5 mg/ml þ 5 mg/ ml; Carbocain-adrenalin, Astra-Zeneca, Sweden), was infiltrated in the operating area. Antibiotics and cortisone were routinely administered to all patients during
the first 24 h (benzyl penicillin 3 g 3 or clindamycin 600 mg 3 in case of penicillin allergy and 4 mg betamethasone 4) starting immediately before the operation. To avoid postoperative swelling of the lower lip and abrasion of the corner of the mouth a steroid cream was frequently used throughout the operation. The surgical technique for both sagittal split osteotomy and vertical ramus osteotomy were performed as described by TERRY & WHITE21. Intermaxillary fixation of the IVRO was achieved by using orthodontic brackets and stainless steel wires (0.4 mm). The wound was sutured with 4-0 Vicryl. All patients were kept on intermaxillary fixation for 4–6 weeks postoperatively. In the SSO the final fixation on each side was achieved with two or three bicortical positional screws through a transbuccal approach. No intermaxillary fixation was used postoperativly with the exception of guiding elastics. Results Intraoral vertical ramus osteotomy
Questionnaires Fifty-three completed questionnaires representing 106 operated sides were returned and analyzed. The returned questionnaires reported immediate NSD after IVRO in 11 operated sides (10.4%); three of them regained full sensibility during the first year whereas eight (7.5%) sides had long lasting NSD. In one of the patients, the NSD was bilateral (Table 1). Four patients out of seven (57%) with long lasting NSD described the effect of the disturbance as mild (Fig. 2). Ninety-eight percent of the patients operated for IVRO were satisfied with the result of the operation. The only patient, who was dissatisfied, did not have any long lasting NSD after the operation.
Record review In the files of the 53 patients with 106 operated sides, who returned completed
Table 1. NSD after IVRO and SSO as reported in returned questionnaires and patients record Record review Operation IVRO SSO
Questionnaires
Total sides
Immediate
Long lasting
Immediate
Long lasting
106 86
8 33
4 7
11 25
8 10
Neurosensory disturbance after sagittal split
249
immediate NSD in 33 operated sides (38.4%). Twenty-six of the affected sides regained full sensibility during the first postoperative year; thus seven operated sides (8.1%) remained with long lasting NSD (Fig. 1). Discussion
Fig. 1. The difference between immediate and long lasting NSD in both record review (RR) and questionnaire (Q).
questionnaires, immediate NSD was recorded in eight operated sides (7.5%). Four of them regained full sensibility over a period of one year, leaving four sides (3.8%) with long lasting NSD (Fig. 1). Sagittal split osteotomy
Questionnaires Questionnaires were returned from 43 patients with 86 operated sides. Immediate NSD was reported in 25 operated sides (29%), 15 sides regained full sen-
sibility after one year while the remaining 10 sides (11.6%) continued to have long lasting NSD. Fifty percent of the patients with NSD after SSO described the effect of NSD as mild to moderate (Fig. 2). Four out of the 43 patients (9%) were not satisfied with the result of the operation but only one attributed the dissatisfaction to sensory impairment.
Record review Reviewing of the 43 patients, who returned the questionnaires, showed
Fig. 2. Patients discomfort after SSO and IVRO according to the questionnaire.
The evaluation of NSD along the distribution of the inferior alveolar nerve (chin and lower lip) can be performed by either purely subjective (questionnaires), relatively objective (static light touch, brush directional discrimination, two-point discrimination, and thermal discrimination) and purely objective (trigeminal somatosensory evoked potentials (TSEP)16, sensory nerve action potential (SNAP)9, and blink reflex (BR)10) methods. The purely objective methods of evaluation are not easily applicable. Thus most studies depend on subjective and the relatively objective evaluation; the latter always considered by many authors as an objective evaluation. Some authors4,17,23 have shown that patients’ subjective evaluations give a higher incidence of NSD than relatively objective evaluations while others have reported the opposite12,26. A good correlation between the subjective evaluation and 2-point discrimination (objective test) has also been reported3. However, it is only the patient who experience whether his/her sensibility has been changed. Therefore, in this study we chose the subjective evaluation to assess the NSD after sagittal split osteotomy. Upon reviewing the literature one finds big differences in the armamentarium used in objective evaluation tests of NSD. This could lead to differences in the definition of NSD. Such disadvantages could be solved by standardization of the instrument used for the tests as described by GHALI & EPKER6 in 1989. The reported immediate postoperative NSD after SSO in the previous studies was high ranging from 54%17 to 100%23. The high incidence of the immediate NSD could be caused by direct manipulation of neurovascular bundle during the operation, which often becomes swollen. As the bundle is confined to a limited bony space after fixation, nerve damage (neurapraxia) could occur. Neurapraxia is an interruption in conduction of the impulse down the nerve fiber, there is no axonal degeneration and the recovery takes place without wallerian degeneration11,18. This is probably a biochemical lesion caused by
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Al-Bishri et al.
concussion or shock-like injuries to the fiber. Compression or relatively mild, blunt blows, bring about neurapraxia. There is a temporary loss of function, which is reversible within hours to months of the injury (the average is 6–8 weeks). In our study, the record of the patients showed immediate postoperative NSD in 33 operated sides (38.4%) while the returned questionnaire showed that 25 operated sides (29%) was affected by NSD. Of those 26 of the affected sides according to the patient’s record and 15 affected side according to the questionnaire regained full sensibility during the first postoperative year. Thus long lasting NSD was present in 8.1% and 11.6% of operated side according to the patient’s record and the questionnaire, respectively. On the other hand, the immediate NSD after IVRO was reported in eight (7.5%) and 11 operated sides (10.4%) in records and questionnaires, respectively. Long lasting NSD after IVRO was 3.8% of the operated sides (four sides) in the records and 7.5% (eight sides) in the questionnaire. Our result showed higher incidence of immediate NSD after SSO in the records than in the questionnaires, while the opposite was true in the case of IVRO. This could reflect a higher concern and expectation of surgeons on NSD after SSO than after IVRO. It might also be difficult for the patients to remember a mild short NSD immediately after the operation when asked a year or more later. The absence of nerve manipulation during IVRO operation could also contribute to the lower incidence of the immediate NSD after the operation. In the case of long lasting NSD, the returned questionnaires showed higher incidence than the reviewed records for both SSO and IVRO. The higher incidence of the long lasting NSD in the questionnaire comparing to the patients records is in agreement with the results reported by PRATT et al. 199617. Our study showed a lower incidence of the long lasting NSD after IVRO compared to SSO (IVRO, 3.8% in the reviewed record and 7.5% in the returned questionnaire, SSO, 8.1% in the reviewed records and 11.6% in the returned questionnaire) these results are in agreement with the results reported previously. WALTER & GREGG23 observed that their patients subjectively complained of chronic NSD in 70% of IVRO and 100% of SSO, whereas an objective test indicated NSD in 35% of
IVRO and 84.6% of SSO operated sides. ZAYTOUN et al.27 reported no NSD after IVRO and 68% in the SSO one year after the operation. WESTERMARK et al.24 reported an incidence of NSD of 9%in the IVRO and 39.4% in the SSO. The difference in the incidence of immediate NSD after SSO and IVRO among both questionnaires and the patient’s records was significant. The NSD was described as mild in 57% of the affected patients in the IVRO group and no patient described his disturbance as moderate to severe or severe. Fifty percent (four patients) of the affected patients in the SSO describe
Appendix A.Questionnaire
the effect as moderate to severe and none of them described the effect as a severe effect, all the four patients were above the age of 40 years. This coincided with the result reported by WES25 in that the TERMARK et al. in 1999 older patients paid more attention to the NSD than the younger patients did. Regarding patient satisfaction 98% of the IVRO and 91% of the SSO patients were satisfied. The only one patient who was not satisfied in the IVRO group was not affected by NSD but due to functional reason. Out of the four patients who were not satisfied in the SSO group only one was due to NSD.
Neurosensory disturbance after sagittal split
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