Journal of the Royal Society of Medicine Volume 72 January 1979
21
Disorders of ocular motility in craniofacial dysostosis' Brian Greaves FRCS Jane Walker DBO(D) Kenneth Wybar FRCS Hospitalfor Sick Children, Great Ormond Street, London WCJ 'Craniofacial dysostosis' is a comprehensive term applied to a variety of deformities of the skull which arise because of a defect in the development of the primitive mesoderm, which is concerned in the formation of the bones of the skull (including the bony orbit), so that there is a premature synostosis of the suture lines in the base of the skull and also to some extent in the vault. It is almost certain that the condition is determined early in intrauterine life (sometimes as an inherited disorder) so that the defects are evident in the newborn, but the full effects usually become obvious only in the early years of life when there is normally a fairly rapid and uniform expansion of the skull and brain. These effects also become apparent when adjacent and relatively unaffected structures progress in a normal way (or in more or less normal ways) so that there is an ever increasing degree of asymmetry of certain parts of the bony structure of the skull and face. There may be other associated bony defects such as syndactyly and synarthrosis. There are various forms of craniofacial dysostoses, but in this paper attention is given only to three conditions - oxycephaly, Crouzon's disease and hypertelorism - which have been studied in detail in a series of 35 cases (Table 1). The general features of these three conditions, which are the most common of the various craniofacial dysostoses, have been discussed previously (Walker & Wybar 1976) together with some details of the anomalies of the eyes which are characteristic features of a significant number of cases - optic atropy, certain forms of squint and nystagmus; but this paper is confined to a reappraisal of the cases of squint with particular emphasis on the different mechanisms involved in their production. Special mention is made also of the changes in the nature of the disorders of ocular motility which follow the elaborate surgical techniques adopted in recent years for the amelioration of the severe cosmetic deformities of the various conditions and which embrace neurosurgical and plastic procedures (Tessier 1967); this operation was carried out in 19 of the 35 cases (Table 1). Squint in craniofacial dysostosis Some form of squint is common in the craniofacial dysostoses (29 of the 35 cases) (Table 2). Table 1. Nature of craniofacial dysostoses and cases involved in Tessier operation
Oxycephaly disease
Hypertelorism
Total
10
5
20
35
4
3
12
19
Crouzon's No. of cases in series No. of cases involved in Tessier procedure
Paper read to Section of Ophthalmology, 10 November 1977. Accepted 20 March 1978 0 141-0768/79/010021-04/$O 1.00/0
0) 1979 The Royal Society of Medicine
22
Journal of the Royal Society of Medicine Volume 72 January 1979
There seems to be a general impression that an exodeviation is a common feature in the craniofacial dysostoses, and this is true in hypertelorism (10 of the 20 cases) and to some extent in Crouzon's disease (2 of the 5 cases), but an esodeviation is a more common feature in oxycephaly (7 of the 10 cases). Special interest is centred on the 19 cases who underwent the Tessier procedure; in oxycephaly and in Crouzon's disease there was no change in the basic nature of the deviation, but in contrast in hypertelorism most cases developed an esodeviation of a consecutive type when there was an exodeviation before the operation, or of a primary nature when there was no squint before the operation (Table 3). It is obvious that this change in the squint from an exodeviation to esodeviation in hypertelorism (Figure 1) may be related simply to the shifting of each orbit in a nasal direction so that there is a marked reduction in the interpupillary Table 2. Incidence of squint
Crouzon's Oxycephaly disease Esotropia Exotropia Hypertropia Orthotropia
2 2
7 1 10 1
-
1
Hypertelorism
Total
4 10 24
13 13 3 6
* 1 case hypertropia with esotropia
Table 3. State of squint before and after,Tessier operation
Oxycephaly
Crouzon's disease
Hypertelorism
Before After
Before After
Before After
Esotropia Exotropia
3 1
3 1
-
-
Orthotropia
-
-
2 1
2 1
2 7 3
10 2 -
distance, but it may also be related in many cases to the limitation of abduction which frequently follows the operation and persists for a considerable period of time, sometimes even permanently. It is interesting, however, to note that the esodeviation is liable to remain even when there is a gradual restoration of full abduction as the mechanical effects of the operation subside, so that squint surgery becomes necessary, particularly when there is potential binocular vision with an awareness of diplopia or when the deviation is sufficient to be cosmetically unsightly. It is important, however, to delay any such operation until it is certain that there is no prospect of any spontaneous improvement; this usually means an interval of at least six months. 'V' phenomenon Attention must be paid to the frequent occurrence of the 'V' phenomenon in the cases of this series (27 of the 29 squinting cases) (Table 4). This was emphasized by Limon de Brown (1974) who found consistent evidence of the 'V' phenomenon in all 10 cases of oxycephaly and Crouzon's disease that she studied; she considered that the 'V' phenomenon was the result of a mechanical defect rather than the result of a neurogenic lesion. This was based on the assumption that the shallowness of each orbit in an anteroposterior direction results in a diminished support of the eyeball so that a greater reliance is placed on the supporting role of the inferior transverse ligament of Lockwood (suspensory ligament of the eyeball) with an overaction of the inferior oblique and inferior rectus, which are associated anatomically with the ligament, in an attempt to try and compensate for the diminished effectivity of the
Journal of the Royal Society ofMedicine Volume 72 January 1979
23
Figure 1. Consecutive esotropia after Tessier operation
ligament. This leads to a secondary underaction of the superior oblique and superior rectus, but it seems more likely that the superior oblique weakness which is a common feature of oxycephaly and Crouzon's disease is of a primary nature. This may not necessarily be obvious on an assessment of the degree of restricted movement of each eye in a position of depression in adduction, but it is more readily detected by the Bielschowsky head-tilting test which provides a positive response in the presence of a superior oblique paresis; a forcible tilting of the head to the side of the affected eye results in an updrift of the eye because the elevating influence of the superior rectus is not neutralized by the depressing influence of the superior oblique when an attempt is made by the superior rectus and superior oblique to compensate for the excyclotropic position of the eye which follows the head tilting. A positive response is readily apparent in each eye when the squint is essentially of the alternating type, but it is less easy to demonstrate the effect in the dominant eye in a squint when there is an obvious preference to fix with one particular eye. It is evident, however, that in such a case the bilateral nature of the superior oblique paresis is apparent when surgical treatment is incorrectly limited to the more affected eye. It seems likely that the restricted anteroposterior diameter of the orbit in oxycephaly and Crouzon's disease, and also some anomalous development of the bony structures around the suspensory
Table 4. Incidence of' V' phenomenon in squints Crouzon's
Oxycephaly disease Esotropia Exotropia Hypertropia with esotropia
7 1 1
2 1 -
Hypertelorism
Total
4 10 1
13 12 2
24
Journal of the Royal Society of Medicine Volume 72 January 1979
Figure 2. Change in line of pull of superior oblique in hypertelorism. Continuous line represents orbit after lateral displacement and abnormal line of pull. (Drawing by Mr T Tarrant, Institute of Ophthalmology)
trochlea, result in an underaction on the tendinous part of the superior oblique which may be purely of a mechanical nature, but there may also be some developmental anomaly of the muscle. In hypertelorism a weakness of the superior oblique plays a significant role in the 'V' phenomenon which is a common feature of the condition, but the mechanism of this weakness is different. In hypertelorism there is a displacement laterally of each orbit, but this displacement does not affect the orbit apex. It follows that a displacement of the eye laterally without any real change in the position of the trochlea increases the angle of the line of pull of the superior oblique with the vertical meridian (Figure 2), with a decrease in its effectiveness as a depressor of the eye. Furthermore, the even greater incidence of the 'V' phenomenon in Table 5. Incidence of' V' phenomenon before and after Tessier operation
Esotropia Exotropia
Oxycephaly
Crouzon's disease
Before After
Before After
Before After
I
1 7
3 I
3 I
-
1
Hypertelorism 9 2
hypertelorism after the Tessier operation (Tarble 5) may be regarded as the result of an increased weakness of the action of the superior oblique which is prone to occur because of some degree of interference with its normal function in the region of the trochlea.
Acknowledgment: The cases in this series were under the care of Mr David Matthews at the Hospital for Sick Children, Great Ormond Street, and were examined in the Eye Department as part of the elaborate routine assessment to determine the appropriateness of the Tessier operation. References Limon de Brown E (1974) Proceedings of the 2nd International Strabismological Association. Diffusion Generale de Librairie, Paris; p 371 Tessier P (1967) Annales de chirurgie plastique 12, 273 Walker J & Wybar K (1976) Transactions of the 3rd International Congress of Orthoptists. Stratton Intercontinental, New York; p 229
21
Disorders of ocular motility in craniofacial dysostosis' Brian Greaves FRCS Jane Walker DBO(D) Kenneth Wybar FRCS Hospitalfor Sick Children, Great Ormond Street, London WCJ 'Craniofacial dysostosis' is a comprehensive term applied to a variety of deformities of the skull which arise because of a defect in the development of the primitive mesoderm, which is concerned in the formation of the bones of the skull (including the bony orbit), so that there is a premature synostosis of the suture lines in the base of the skull and also to some extent in the vault. It is almost certain that the condition is determined early in intrauterine life (sometimes as an inherited disorder) so that the defects are evident in the newborn, but the full effects usually become obvious only in the early years of life when there is normally a fairly rapid and uniform expansion of the skull and brain. These effects also become apparent when adjacent and relatively unaffected structures progress in a normal way (or in more or less normal ways) so that there is an ever increasing degree of asymmetry of certain parts of the bony structure of the skull and face. There may be other associated bony defects such as syndactyly and synarthrosis. There are various forms of craniofacial dysostoses, but in this paper attention is given only to three conditions - oxycephaly, Crouzon's disease and hypertelorism - which have been studied in detail in a series of 35 cases (Table 1). The general features of these three conditions, which are the most common of the various craniofacial dysostoses, have been discussed previously (Walker & Wybar 1976) together with some details of the anomalies of the eyes which are characteristic features of a significant number of cases - optic atropy, certain forms of squint and nystagmus; but this paper is confined to a reappraisal of the cases of squint with particular emphasis on the different mechanisms involved in their production. Special mention is made also of the changes in the nature of the disorders of ocular motility which follow the elaborate surgical techniques adopted in recent years for the amelioration of the severe cosmetic deformities of the various conditions and which embrace neurosurgical and plastic procedures (Tessier 1967); this operation was carried out in 19 of the 35 cases (Table 1). Squint in craniofacial dysostosis Some form of squint is common in the craniofacial dysostoses (29 of the 35 cases) (Table 2). Table 1. Nature of craniofacial dysostoses and cases involved in Tessier operation
Oxycephaly disease
Hypertelorism
Total
10
5
20
35
4
3
12
19
Crouzon's No. of cases in series No. of cases involved in Tessier procedure
Paper read to Section of Ophthalmology, 10 November 1977. Accepted 20 March 1978 0 141-0768/79/010021-04/$O 1.00/0
0) 1979 The Royal Society of Medicine
22
Journal of the Royal Society of Medicine Volume 72 January 1979
There seems to be a general impression that an exodeviation is a common feature in the craniofacial dysostoses, and this is true in hypertelorism (10 of the 20 cases) and to some extent in Crouzon's disease (2 of the 5 cases), but an esodeviation is a more common feature in oxycephaly (7 of the 10 cases). Special interest is centred on the 19 cases who underwent the Tessier procedure; in oxycephaly and in Crouzon's disease there was no change in the basic nature of the deviation, but in contrast in hypertelorism most cases developed an esodeviation of a consecutive type when there was an exodeviation before the operation, or of a primary nature when there was no squint before the operation (Table 3). It is obvious that this change in the squint from an exodeviation to esodeviation in hypertelorism (Figure 1) may be related simply to the shifting of each orbit in a nasal direction so that there is a marked reduction in the interpupillary Table 2. Incidence of squint
Crouzon's Oxycephaly disease Esotropia Exotropia Hypertropia Orthotropia
2 2
7 1 10 1
-
1
Hypertelorism
Total
4 10 24
13 13 3 6
* 1 case hypertropia with esotropia
Table 3. State of squint before and after,Tessier operation
Oxycephaly
Crouzon's disease
Hypertelorism
Before After
Before After
Before After
Esotropia Exotropia
3 1
3 1
-
-
Orthotropia
-
-
2 1
2 1
2 7 3
10 2 -
distance, but it may also be related in many cases to the limitation of abduction which frequently follows the operation and persists for a considerable period of time, sometimes even permanently. It is interesting, however, to note that the esodeviation is liable to remain even when there is a gradual restoration of full abduction as the mechanical effects of the operation subside, so that squint surgery becomes necessary, particularly when there is potential binocular vision with an awareness of diplopia or when the deviation is sufficient to be cosmetically unsightly. It is important, however, to delay any such operation until it is certain that there is no prospect of any spontaneous improvement; this usually means an interval of at least six months. 'V' phenomenon Attention must be paid to the frequent occurrence of the 'V' phenomenon in the cases of this series (27 of the 29 squinting cases) (Table 4). This was emphasized by Limon de Brown (1974) who found consistent evidence of the 'V' phenomenon in all 10 cases of oxycephaly and Crouzon's disease that she studied; she considered that the 'V' phenomenon was the result of a mechanical defect rather than the result of a neurogenic lesion. This was based on the assumption that the shallowness of each orbit in an anteroposterior direction results in a diminished support of the eyeball so that a greater reliance is placed on the supporting role of the inferior transverse ligament of Lockwood (suspensory ligament of the eyeball) with an overaction of the inferior oblique and inferior rectus, which are associated anatomically with the ligament, in an attempt to try and compensate for the diminished effectivity of the
Journal of the Royal Society ofMedicine Volume 72 January 1979
23
Figure 1. Consecutive esotropia after Tessier operation
ligament. This leads to a secondary underaction of the superior oblique and superior rectus, but it seems more likely that the superior oblique weakness which is a common feature of oxycephaly and Crouzon's disease is of a primary nature. This may not necessarily be obvious on an assessment of the degree of restricted movement of each eye in a position of depression in adduction, but it is more readily detected by the Bielschowsky head-tilting test which provides a positive response in the presence of a superior oblique paresis; a forcible tilting of the head to the side of the affected eye results in an updrift of the eye because the elevating influence of the superior rectus is not neutralized by the depressing influence of the superior oblique when an attempt is made by the superior rectus and superior oblique to compensate for the excyclotropic position of the eye which follows the head tilting. A positive response is readily apparent in each eye when the squint is essentially of the alternating type, but it is less easy to demonstrate the effect in the dominant eye in a squint when there is an obvious preference to fix with one particular eye. It is evident, however, that in such a case the bilateral nature of the superior oblique paresis is apparent when surgical treatment is incorrectly limited to the more affected eye. It seems likely that the restricted anteroposterior diameter of the orbit in oxycephaly and Crouzon's disease, and also some anomalous development of the bony structures around the suspensory
Table 4. Incidence of' V' phenomenon in squints Crouzon's
Oxycephaly disease Esotropia Exotropia Hypertropia with esotropia
7 1 1
2 1 -
Hypertelorism
Total
4 10 1
13 12 2
24
Journal of the Royal Society of Medicine Volume 72 January 1979
Figure 2. Change in line of pull of superior oblique in hypertelorism. Continuous line represents orbit after lateral displacement and abnormal line of pull. (Drawing by Mr T Tarrant, Institute of Ophthalmology)
trochlea, result in an underaction on the tendinous part of the superior oblique which may be purely of a mechanical nature, but there may also be some developmental anomaly of the muscle. In hypertelorism a weakness of the superior oblique plays a significant role in the 'V' phenomenon which is a common feature of the condition, but the mechanism of this weakness is different. In hypertelorism there is a displacement laterally of each orbit, but this displacement does not affect the orbit apex. It follows that a displacement of the eye laterally without any real change in the position of the trochlea increases the angle of the line of pull of the superior oblique with the vertical meridian (Figure 2), with a decrease in its effectiveness as a depressor of the eye. Furthermore, the even greater incidence of the 'V' phenomenon in Table 5. Incidence of' V' phenomenon before and after Tessier operation
Esotropia Exotropia
Oxycephaly
Crouzon's disease
Before After
Before After
Before After
I
1 7
3 I
3 I
-
1
Hypertelorism 9 2
hypertelorism after the Tessier operation (Tarble 5) may be regarded as the result of an increased weakness of the action of the superior oblique which is prone to occur because of some degree of interference with its normal function in the region of the trochlea.
Acknowledgment: The cases in this series were under the care of Mr David Matthews at the Hospital for Sick Children, Great Ormond Street, and were examined in the Eye Department as part of the elaborate routine assessment to determine the appropriateness of the Tessier operation. References Limon de Brown E (1974) Proceedings of the 2nd International Strabismological Association. Diffusion Generale de Librairie, Paris; p 371 Tessier P (1967) Annales de chirurgie plastique 12, 273 Walker J & Wybar K (1976) Transactions of the 3rd International Congress of Orthoptists. Stratton Intercontinental, New York; p 229
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