Morbidity of the infraorbital nerve following orbitozygomatic complex fractures

Morbidity of the infraorbital nerve following orbitozygomatic complex fractures

Morbidity of the infraorbital nerve following orbitozygomatic complex fractures J. P. M. Vriens, K. F. Moos West of Scotland Regional Plastie and Max...

640KB Sizes 0 Downloads 6 Views

Morbidity of the infraorbital nerve following orbitozygomatic complex fractures J. P. M. Vriens, K. F. Moos

West of Scotland Regional Plastie and Maxillofacial Surgery Unit, Canniesburn Hospital, Switchback Road, Bearsden, Glasgow G61 1QL, UK

S U M M A R Y. Acute sensory disturbances in the distribution of the infraorbital nerve are recognised signs present in patients with orbitozygomatic complex fractures. Fifty consecutive patients with unilateral orbitozygomatic complex fractures were evaluated with regard to the long-term infraorbital nerve sensory function. The highest incidence of long-term neurosensory deficits occurred in fractures with an undistracted frontozygomatic suture. This is in complete agreement with the distribution of long-term neurosensory deficits regarding the method of treatment for orbitozygomatic complex fractures. In our series slightly more than one-third of the patients had third or fourth degree nerve injuries, according to Sunderland's classification, to the infraorbital nerve following orbitozygomatic complex fractures. This outcome should influence the managemeht of orbitozygomatic complex fractures. With regard to fixation of unstable malar fractures in relation to sensory recovery of the infraorbital nerve, miniplate osteosynthesis is recommended as opposed to wire fixation in all unstable bone fractures when there is displacement. Furthermore, open reduction and fixation of an orbitozygomatic complex fracture offer a better prognosis for complete recovery of the infraorbital nerve function than elevation only with or without Kirschner wire fixation.

tures based on the Seddon and Sunderland classifications.

INTRODUCTION Acute loss of sensory function of the infraorbital nerve following orbitozygomatic complex fractures is often seen because of its close proximity to the orbitozygomatic complex as it passes through the infraorbital sulcus in the floor of the orbit to exit through the infraorbital foramen. Traumatic injury to the infraorbital nerve may be due to compression, oedema, ischaemia or laceration. The incidence of long-term neurosensory deficits in different studies varies from 10% to 50% (Lund, 1971; Momma and Pfeifle, 1975; Waldhart, 1975; Altonen et al., 1976; Hardt and Steinhiiuser, 1976; Nordgaard, 1976; Reuther et al., 1976; Tajima, 1977; Larsen and Thomsen, 1978; Finlay et al., 1984; Kristensen and Tveteras, 1986; Jungell and Lindqvist, 1987; de Man and Bax, 1988; Souyris et al., 1989; Zachariades et al., 1990; Rohrich and WatumulI, 199 l ; Zingg et al., 1991; Taicher et al., 1993). The wide variability is due to study design, testing methods, use of terminology to describe sensory disturbances and methods of nerve injury classification. The most commonly used classification schemes for nerve injury are those of Seddon (1943) and Sunderland (1951). There is a considerable overlap between the two classification schemes. Because the Seddon and Sunderland classifications are based upon the severity and the degree of tissue injury the time frame for recovery is predictable. The aim of this report is to document infraorbital nerve injury following orbitozygomatic complex frac-

MATERIALS AND METHODS We evaluated 50 consecutive patients following orbitozygomatic complex fractures with regard to the sensory function of the infraorbital nerve. Mean patient's age was 36.6 years with a median of 32.5 years. Thirty-seven of the patients were male and 13 female. The 50 patients sustained unilateral fractures of the orbitozygomatic complex. Fractures were classified according to the system of Henderson, which identifies the following anatomical groups of orbitozygomatic complex fractures: undisplaced (type I), solitary zygomatic arch (type II), frontozygomatic suture undistracted (type III), frontozygomatic suture distracted (type IV), blow-out fracture (type V), orbital rim fracture (type VI) and comminuted or other fracture (type VII). The total series consisted of 9 type I fractures, 17 type III fractures, 17 type IV fractures and 7 type V fractures. Surgery was performed in 41 cases and this was done within 1 week after the trauma in 22 patients, within 2 weeks in 14 patients and within 3 weeks in 5 patients. The surgical treatments varied depending on the type of fracture and stability of the orbitozygomatic complex after elevation. Treatment modalities included Rowe's elevation via a Gillies approach with or without fixation-by means of a Kirschner wire, these accounted for 9 and 8 cases respectively. Sixteen patients 363

364 Journal of Cranio Maxillo-Facial Surgery Table 1- Patients' details Number of patients Age Sex Distribution of types of OZC fracture (Henderson's classification) Distribution of treatment

Distribution of time interval between trauma and surgical intervention (n = 41)

underwent open reduction and fixation by means of mini- or microplate osteosynthesis. Orbital floor exploration and reconstruction by means of silastic implant or autogeneous bone graft was performed in 8 patients. The patient's details are summarised in Table 1. The neurosensory evaluation included tactile, directional, pain and thermal sensation tests within the skin areas supplied by the infraorbital nerve. The areas examined were anterior cheek, lateral side of the nose and upper lip and this was done bilaterally with the non-affected side providing the control. Light touch sensation was examined with a blunt metal rod, directional sensation with a dental cotton swab, pain sensation with a 27 gauge needle and thermal (cold) sensation with an ethylchloride saturated dental swab. The 6 sites to which the stimuli were applied were selected in a random order and stimulated 4 times for each sensory modality. Three identical responses over the different ipsilateral sites were regarded as the test end-result and recorded as positive or negative sensation after comparing the test side with the control side. Sensory function was evaluated in timeintervals of 4 weeks, until at least 6 months following the trauma, or in the event of early complete return of sensation, until the date of normal sensory function. Contingency tables were used to arrange the data for the presence or absence of long-term neurosensory deficits and for the variables: type of orbitozygomatic complex fracture, treatment modalities and time intervals between the trauma and surgery. A chisquared (Z2) test was used to test whether the distribution of individuals a m o n g the categories of one variable was independent of their distribution a m o n g the categories of the other. Because the expected numbers were small the Yate's continuity correction was used. One-way analysis of variance was used to compare the means of recovery rate to normal sensation among the different types of orbitozygomatic complex fracture. Because of unequal standard deviations for each subgroup the values were logarithmically transformed.

50 Mean: 36.6 years Median: 32.5 years 13 female 37 male Type I: n = 9 Type III: n = 17 Type IV:n=17 Type V: n = 7 No surgical treatment Rowe's elevation Rowe's elevation+ K-wire fixation Open reduction + mini- and/or microplate fixation Orbital floor reconstruction ~<1 week: n = 22 ~<2 weeks: n = 14 ~<3 weeks: n = 5

n=9 n=9 n=8 n=16 n=8

RESULTS The overall long-term result of complete sensory recovery of the infraorbital nerve following orbitozygomatic fractures in our series was 64 %. Return to normal sensation occurred on average in 15.25 weeks (range 4-26 weeks) after the trauma. In 13 patients (26 %), total anaesthesia in the distribution of the infraorbital nerve was still present at a mean of 6.5 months follow-up (range 6-9 months). Some of the sensory modalities tested returned to normal in 5 patients (10 %) at a mean of 6.6 months after trauma (range 6-9 months). The correlation between type of orbitozygomatic fracture and recovery of sensation showed an incidence of long-term neurosensory deficits of 33.3 % in type I fractures, 64.7 % in type III fractures, 11.8 % in type IV fractures and 28.6% in type V fractures (Table 2). Comparison of long-term neurosensory deficits a m o n g the different types of orbitozygomatic complex fracture was significant at the 2.5 % level, suggesting that there m a y be an association between neurosensory deficit and type of fracture, the prevalence of neurosensory deficit being higher among patients with a type I I I and lower a m o n g patients with a type IV than among type I and type V orbitozygomatic complex fractures. In cases with complete return of sensation to normal and in relation to the time-interval after the trauma it took 4-26 weeks (mean 11.3 weeks) in type I fractures, 4-17 weeks (mean 9 weeks) in type III fractures, 4-26 weeks Table 2 Comparison of long-term neurosensory deficits (NSD) among the different types of orbitozygomatic complex fracture according to Henderson's classification NSD+ NSDTotal

Type I

Type III

Type IV

Type V

Total

3 6 9

11 6 17

2 15 17

2 5 7

18 32 50

Chi-square test after Yate's continuity correction X2 = 10.59, d.f. = 3, p < 0.025.

.

.

.

.

/

Morbidity of the infraorbital nerve following orbitozygomatic complex fractures Table 3 - Mean recovery rates (weeks) to normal sensation (n = 32) among the different types of orbitozygomatic complex fracture according Henderson's classification (in brackets logarithmic transformation of the values because of equalizing s and of removing skewness in each group)

Number (ni) Mean (x0 s.d. (s)

Type I

Type III

Type IV

Type V

6 11.33 (0.77) 0.41

6 9 (0.85) 0.29

15 18.07 (1.18) 0.25

5 19 (2.08) 0.35

One-way analysis of variance F = 4.3, d.f. = (3.28), p < 0.025.

(mean 18.1 weeks) in type IV fractures and 4-26 weeks (mean 19 weeks) in type V fractures for recovery of the sensory function (Table 3). Comparison of means in the recovery rate to normal sensation among the different types of orbitozygomatic complex fracture was significant at the 2.5 % level, suggesting that there may be an association between type of fracture and time-lapse for recovery to normal sensation. Because of the close relationship between type of fracture and treatment performed a similar trend in the recovery of sensory function was shown regarding method of treatment. The distribution of long-term neurosensory deficits present was 77.8 % for elevation only, 37.5% for elevation and fixation with a Kirschner wire, 12.5% for open reduction and fixation, and 25 % for orbital floor reconstruction. Of the cases which did not receive any surgical treatment, 44.4 % had persistent neurosensory deficits (Table 4). Comparison of long-term neurosensory deficits among the treatment modalities was significant at the 2.5% level, suggesting that there may be an association between long-term neurosensory deficits and the management of patients with orbitozygomatic complex fracture. The prevalence of long-term neurosensory deficit being higher among closed elevation and lower among open reduction and fixation of the fracture than among the other treatments performed. When drawing comparison with open reduction and plate fixation and other types of treatment among the different types of fracture, the results were clearly more significant (Table 5). The majority of the patients who had surgical treatment for the orbitozygomatic complex fracture and with no long-term neurosensory deficits present, underwent surgery within 1 week after the trauma as opposed to patients with persistent impairment of the sensory function of the infraorbital nerve (Table 6). However, this was statistically significant at the 5% level, the results gave the impression that the prevalence of long-term neurosensory deficits was dependent on the time-lapse between trauma and treatment.

Table 5 - Comparison of long-term neurosensory deficits (NSD) among the different types of orbitozygomatic complex fracture according to Henderson's classification

NSD+ NSDTotal

Type I

Type III

Type IV

Type V

Total

31" 6t 9

llt 6t 17

I* 15' 16

1" 5* 6

16 32 48

Chi-square test after Yate's continuity correction Z~ = 13.59, d.f. = 3, p < 0.005. * With open reduction and fixation. t Without open reduction and fixation. Table 6 - Comparison of long-term neurosensory deficits (NSD) among the distribution of time intervals between the trauma and the moment of surgical intervention (n = 41)

NSD + NSD Total

~< 1 week

~< 2 weeks

~< 3 weeks

Total

5 17 22

5 9 14

4 1 5

14 27 41

Chi-square test after Yate's continuity correction Z 2 = 6.0, d.f. = 2, p < 0.05. Table 7 - Distribution of different degrees of nerve injury in relation to type of orbitozygomatic complex fracture

1st degree (3) 2nd degree 3rd degree 4th degree Total

Type I

Type III

Type IV

Type V

Total

4 2 1 2 9

4 3 3 7 17

4 10 1 2 17

1 4 0 2 7

13 19 5 13 50

Table 8 - Distribution o f type of nerve lesion in relation to type of orbitozygomatic complex fracture

Neuropraxia Axonotmesis Total

Type I

Type III

Type IV

Type V

Total

4 5 9

4 13 17

4 13 17

1 6 7

13 37 50

On the basis of time-lapse to recovery of sensory function of the infraorbital nerve or persistent presence of neurosensory deficits in the distribution of the infraorbital nerve, the outcome of the neurosensory tests resulted in 13 (26 %) neuropraxia, and in 37 (74 %) axonotmesis lesions according to Seddon's classification. This corresponds to 13 (26 %) 1st degree type 3, 19 (38%) 2nd degree, 5 (10%) 3rd degree and 13 (26 %) 4th degree injuries according to Sunderland's classification. The distribution of the different degrees of nerve injury in relation to the type of orbitozygomatic complex fracture is shown in Tables 7 and 8 and Figures 1 and 2. There was no

Table 4 Comparison of long-term neurosensory deficits (NSD) among the different treatment modalities performed for orbitozygomatic complex fracture

NSD+ NSDTotal

365

No surgical treatment

Elevation

Elevation + K-wire

Open reduction + fixation

Orbital floor reconstruction

Total

4 5 9

7 2 9

3 5 8

2 14 16

2 6 8

18 32 50

Chi-square test after Yate's continuity correction Z g = 11.37, d.f. = 4, p < 0.025.

366

Journal of Cranio Maxillo-Facial Surgery

,°8 l 6

2 0

I

II Jm iiil type I

l iii type III

~yp~ iv

type v

Fig. 1 - Distribution of nerve injuries according to Sunderland's classification in relation to the type of fracture of orbitozygomatic complex fractures according to Henderson's classification; chi-square test after Yate's continuity correction 1,2 = 11.59, d.f. = 9, p<0.01. []:lstD(3),[]:2ndD,[]:3rdD,[]:4thD.

15

10

I°°

type I

type III

type IV

type V

Fig. 2 - Distribution of nerve injuries according to Seddon's classification in relation to the type of fracture of orbitozygomatic complex fractures according to Henderson's classification; chi-square test after Yate's continuity correction I, 2 = 2.18, d.f. = 3. I : neuropraxia, [] : axonotmesis.

significant difference between type of orbitozygomatic complex fracture and type of nerve lesion according to Seddon's classification, however, according to Sunderland's classification of nerve injuries this was significant at the 1% level. This indicates an association between type of fracture and type of nerve lesion, as was to be expected. DISCUSSION Orbitozygomatic complex fractures are common injuries of the craniomaxillofacial skeletal. The classification system designed by Henderson is based on anatomical types and on predicted stability upon reduction. Types III, IV and VII frequently require fixation of the main body of the zygoma, whereas in types I, II, V and VI no displacement of the main body of the zygoma occurs. Sequelae of orbitozygomatic complex fractures include effects on the orbital contents and facial aesthetics and are an indication for surgical treatment. Sensory disturbances in the distribution of the infraorbital nerve are almost always

present in orbitozygomatic fractures (Rowe, 1985). The nerve can be damaged through oedema, ischaemia, compression, traction and/or rupture by the bony spicules of a disrupted orbital floor and/or sharp edge of the fracture line. According to the literature, the incidence of sensory disturbances in orbitozygomatic complex fractures in the immediate post-trauma period varies from 24% to 94% (Wiesenbaugh, 1970; Lund, 1971; Schmoker et al., 1975; Waldhart, 1975; Reuther et al., 1976; Tajima, 1977; Ellis et al., 1985; Jungell and Lindqvist, 1987; de Man and Bax, 1988 ; Schindelhauer, 1990; Zingg et al., 1991; Taicher et al., 1993). Studies with the lowest incidence of sensory dysfunction use unrefined methods for sensory testing and tend to be retrospective. However, the vast majority of patients will have neurosensory deficits in the function of the infraorbital nerve initially following orbitozygomatic complex fractures, because in 95% of orbitozygomatic fractures the fracture line involves the infraorbital foramen (Schilli, 1990). Theoretically absence of neurosensory deficits implies that the fracture may be lateral, medial or posterior to the

Morbidity of the infraorbital nerve following orbitozygomatic complex fractures 367

infraorbital groove or canal. All patients in our series had neurosensory deficits in the cutaneous distribution of the infraorbital nerve immediately after the trauma. This can be explained by the relatively small number of patients and a limited number of different types of fracture. The long-term outcome of overall sensory function following orbitozygomatic complex fractures is in agreement with the results found by many authors (Lund, 1971; Waldhart, 1975; Hardt and Steinhiiuser, 1976; Reuther et al., 1976; Tajima, 1977 Finlay et al., 1984; Jungell and Lindqvist, 1987; de Man and Bax, 1988; Zachariades et al., 1990; Zingg et al., 1991; Roeea and Ferra, 1992; Taicher et al., 1993); although we have to recognise that it is difficult, if not impossible, to compare the results among investigators, because there is no 'gold standard' for trigeminal nerve sensory testing. Seddon's classification is based on the time course and completeness of sensory recovery and of necessity is a retrospective diagnosis. Sunderland's classification incorporates the features of Seddon's scheme but includes the amount of nerve tissue damaged and tissue still intact. Where neuropraxia or 1st degree lesions (type 1 and 2) exist, return to normal sensory function occurs within 1 week following nerve injury, 1st degree (type 3) takes 1 to 2 months for complete recovery, but is far earlier than can be explained by axonal regeneration. Complete recovery occurs in 2-4 months in an axonotmesis or 2nd degree nerve injury. A neurotmesis or 3rd, 4th or 5th degree nerve injury will show incomplete recovery of sensory function. Whereas 4th and 5th degree nerve injuries will have a poor prognosis for spontaneous recovery, 3rd degree nerve injury may show partial return of sensation within 3-5 months after the trauma. The most likely cause for 3rd and 4th degree injuries include severe traction or compression. Not all nerve fibres have the same susceptibility to compression injuries and ischaemia. The A/q (myelinated) fibres, responsible for mechanoception (touch), are more susceptible to compression and ischaemia than the A6 (myelinated) and C (unmyelinated) fibres (pain, temperature). Following a compression injury it is quite possible to have a deficit in mechanoception (light touch, moving touch), but intact nociception (pinprick) and thermal discrimination. In our study this phenomenon is reflected by the fact that in 10 % of the cases complete recovery of neurosensory function occurred for only some of the sensory modalities tested. Assuming that no transection or rupture of the entire infraorbital nerve trunk had occurred in our series, 36 % of patients had 3rd or 4th degree nerve injuries. Pathophysiologically this means loss of axonal continuity and endoneurial tubes. In 4th degree injury it also means interruption of the epineurium. Although it is impossible to translate these results to the initial trauma to the nerve, we can report that in at least 18 cases (36 %) these severe nerve injuries were present at the time of injury, as they were still present at 6-9 months after the trauma. This should influence the management of orbitozygomatic complex fractures in general, which has already been indicated by

Jungell and Lindqvist (1987). In their study of 68 patients with zygomatic complex fractures, 9 patients (13.2 %) underwent surgery to the nerve and 6 patients experienced some improvement. In another study, results from neuromicrosurgery to the infraorbital nerve indicate a high degree of successful regeneration, with complete return of sensation in the distribution of the infraorbital nerve in 6 out of 7 cases (Mozsary and Middleton, 1983). The indications for neuromicrosurgery are strongest for the neurotmesis or 3rd, 4th and 5th degree nerve injuries. In cases with a zygoma fracture who were treated only by bone elevation, 49% of all cases have permanent damage of the infraorbital nerve and at the same time > 50% of these patients have re-displacement of the zygoma as reported by Schindelhauer (1990). In our series, the incidence was higher, i.e. 77.8 %. The reason for the damage to the nerve is not only the compression of the nerve for a short period by the displaced zygoma but probably also from additional splits of the orbital floor, along the infraorbital canal. With regard to fixation of unstable zygomatic fractures in relation to sensory recovery of the infraorbital nerve, miniplate osteosynthesis is recommended as opposed to wire fixation in all unstable zygomatic bone fractures where there is displacement (de Man and Bax, 1988). The incidence of postoperative infraorbital nerve sequelae is diminished by 50 % in unstable zygomatic fractures when treated by osteosynthesis with miniplates (Champy et al., 1986). This is in agreement with our findings of only 12.5 % persistent neurosensory deficits after open reduction and fixation with plate osteosynthesis. The results regarding orbital floor reconstruction in which 25 % of the cases had persistent neurosensory deficits are in agreement with the study by Kirkegaard et al. (1986), who found that 30 % of the patients had persistent reduced sensation in the infraorbital nerve distribution area. Andersen et al. (1985) reported an incidence of 22 % of long-term neurosensory deficits in patients operated on for unilateral orbital floor fractures. Although a neurosensory deficit in the distribution of the infraorbital nerve is not regarded as an indication for surgical treatment of orbitozygomatic complex fractures, in the absence of other significant symptoms, 44.4 % of the patients who did not undergo surgery sustained persistent neurosensory deficits. Surgery within 1 week after the trauma will improve the sensory function of the infraorbital nerve. Despite the fact that not all of these patients will seek treatment for alteration in sensation, depending on the nature of the sensory disturbances, there may be a subgroup of patients who would benefit from early surgical treatment to prevent long-term nerve dysaesthesia. Furthermore, open reduction and fixation of an orbitozygomatic complex fracture offers a better prognosis for complete recovery of infraorbital nerve function than elevation only with or without K-wire fixation. Furthermore, early neuromicrosurgical intervention on the infraorbital nerve is indicated in one-third of all orbitozygomatic complex

368 Journal of Cranio Maxillo-Facial Surgery

fractures, in particular in type III fractures, because of a high percentage of 3rd or 4th degree nerve injuries according to Sunderland's classification. Our study evaluated the recovery rate of subjective sensory modalities. A study including more quantitative neurological examination, such as cutaneous pressure thresholds, two-point discrimination and vibratory threshold measurements may give a clearer indication as to choice of treatment. References Altonen, M., A. Kohonen, K. Dickhoff : Treatment of zygomatic fractures: Internal wiring and antral packing reposition without fixation. J. Maxillofac. Surg. 4 (1976) 10%115. Andersen, M., P. Vibe, I. M. Nielsen, K. V. Hall: Unilateral floor fractures. Scand. J. Plast. Reconstr. Surg. 19 (1985) 193-196 Champy, M., J. P. Lodde, J. L. Kahn, P. Keilwasser : Attempt at systematization in the treatment of isolated fractures of the zygomatic bone: techniques and results. J. Otolaryngol. 15 (198) 39-43 Ellis, E., A. El-Atar, K. . Moos: An analysis of 2,067 cases of zygomatico-orbital fracture. J. Oral Maxillofac. Surg. 43 (1985) 417-428 Finlay, P. M., R. P. Ward-Booth, K. F. Moos: Morbidity associated with the use of antral packs and external pins in the treatment of the unstable fracture of the zygomatic complex. Br. J. Oral Maxillofac. Surg. 22 (1984) 18-23 Hardt, H., E. W. Steinhiiuser : Treatment results after zygomaticorbital fractures. Schweiz. Monatsschr. Zahnheilkd. 86 (197) 825-835 Jungell, P., C. Lindqvist: Paresthesia of the infraorbital nerve following fractures of the zygomatic complex. Int. J. Oral Maxillofac. Surg. 16 (1987) 363-367 Kirkegaard, J., O. Greisen, P. E. Hojslet : Orbital floor fractures: early repair and results. Clin Otolaryngol. 11 (1986) 69-73 Kristensen, S., K. Tveteras : Zygomatic fractures: classification and complications. Clin. Otolaryngol. 11 (1986) 123-129 Larsen, O. D., M. Thomsen: Zygomatic fractures. II. A follow-up study of 137 patients. Scand. J. Plast. Reconstr. Surg. 12 (1978) 59-63 Lund, K.: Fractures of the zygoma: a follow-up study of 62 patients. J. Oral Surg. 29 (1971) 557-560 Man, K. de, W. A. Bax: The influence of the mode of treatment of zygomatic bone fractures on the healing process of the infraorbital nerve. Br. J. Oral Maxillofac. Surg. 24 (1988) 419-425 Momma, W. G., K. Pfeifle : Behandlungsergebnisse isolierter Jochbein-Frakturen. Fortschr. Kiefer Gesichtschir. Thieme 19 (1975) 163 Mozsary, P. G., R. A. Middleton: Microsurgical reconstruction of the infraorbital nerve. J. Oral Maxillofac. Surg. 41 (1983) 697-700 Nordgaard, J. O. : Persistent sensory disturbances and diplopia following fractures of the zygoma. Arch. Otolaryngol. 102 (1976) 80-82

Reuther, J., J. E. Hausamen, W. Esswein : Neurologische Storingen nach Frakturen im Kiefer- und Gesichtsbereich. Fortschr. Kiefer Gesichtschir. Thieme. 21 (1976) 290-293 Rocca, A., M. Ferra: Les sequelles des fractures du plancher de l'orbite. Evaluation du dommage corporel. Rev. Stomatol. Chir. Maxillofac. 93 (1992) 80-84 Rohrich, R. J., D. Watumull: The superiority of rigid plate fixation in the management of zygoma fractures and a longterm follow-up clinical study. Plast. Reconstr. Surg. (1991) Rowe, N. L. : Fractures of the zygomatic complex and orbit. In: N. L. Rowe, J. L. Williams (Eds.) : Maxillofacial injuries. Churchill Livingstone, Edinburgh, London, Melbourne, New York 1985 Sehilli, W.: Treatment of zygoma fractures. Oral Maxillofac. Surg. Clin. North Am. 2 (1990) 155-169 Schindelhauer, P. : Zur Therapie der Jochbeinfraktur. Klinische und experimentelle Untersuchungen. Zahn. Mund. Kieferheilkd. 78 (1990) 615-619 Schmoker, R., B. Spiessl, E. Holtgrave, C. Sehotland: Ergebnisse der operativen Versorgung yon Jochbeinfrakturen. Fortschr. Kiefer Gesichtschir. Thieme. 19 (1975) 154-156 Seddon, H. J. : Three types of nerve injury. Brain 66 (1943) 237 Souyris, F., F. Klersy, P. Jammet, C. Payrot : Malar bone fractures and their sequelae. J. Craniomaxillo fac. Surg. 17 (1989) 64-68 Sunderland, S.: A classification of peripheral nerve injuries produced by loss of function. Brain 74 (1951) 491 Taicher, S., L. Ardekian, N. Samet, Y. Shoshani, I. Kaffe : Recovery of the infraorbital nerve after zygomatic complex fractures: a preliminary study of different treatment methods. Int. J. Oral Maxillofac. Surg. 22 (1993) 339-341 Tajima, S. : Malar bone fractures: experimental fractures on the dried skull and clinical sensory disturbances. J. Max.-Fac. Surg. 5 (1977) 150-156 Waldhart, E.: Ergebnisse einer Kontrolluntersuchung von Patienten mit Jochbein-Frakturen. Fortschr. Kiefer Gesichtschir. Thieme 19 (1975) 166-167 Wiesenbaugh, J. M. : Diagnostic evaluation of zygomatic complex fractures. J. Oral Surg. 28 (1970) 204-208 Zachariades, N., D. Papavassiliou, I. Papademetriou : The alterations in sensitivity of the infraorbital nerve following fractures of the zygomaticomaxillary complex. J. Craniomaxillo fac. Surg. 18 (1990) 315-318 Zingg, M., K. Chowdhury, K. Ladraeh, T. Vuillemin, F. Sutter, J. Reveh: Treatment of 813 zygoma-lateral orbital complex fractures. Arch. Otolaryngol. Head Neck Surg. 117 (1991) 611-620

J. P. M. Vriens

Medical Centre Leeuwarden Department of Oral and Maxillofacial Surgery PO Box 888 8901 BR Leeuwarden The Netherlands Paper received 9 May 1995 Accepted 11 September 1995