Transactions 29th European Strabismological Association Meeting – de Faber (ed) © 2005 European Strabismological Association, ISBN 04 1537 211 9

Familial congenital superior oblique palsy

Majid Farvardin, Ali Banihashemi & Mostafa Saadat

Shiraz University of Medical Sciences, Shiraz, Iran

ABSTRACT:

Purpose: Eight patients from three families suffering from congenital superior oblique palsy (SOP) were studied, during a 7 year period in order to investigate the genetic transmission of this disease. Methods: One patient of each family came to the clinic complaining of eye deviation and head tilt. All available family members of these patients were invited and examined. According to results of the alternate prism cover” and “Bielschowsky” test and also presence of symptoms since early childhood and the absence of any history of trauma, congenital SOP was diagnosed.

Results: In “Family A”, the father and his offsprings suffered from congenital SOP. Another family member also had a history of head tilt but didn’t come for examination. In “Family B”, three patients of two consecutive generations suffered from congenital SOP. Two other family members also had a history of head tilt, but didn’t come for examination. In “Family C”, the mother and her daughter suffered from congenital SOP. In the three families 4 patients were operated.

Conclusion: An autosomal dominant inheritance pattern was seen.

1INTRODUCTION

Paralysis of the fourth cranial nerve is the most common cranial nerve paralysis encountered in ophthalmology. 29–67 percent of cases of superior oblique palsy are of the congenital type.2 The congenital cases of this disease usually occurs sporadically. There are limited reports of familial superior oblique palsy in literature.3 Autosomal mode of transmission has been suggested.1,2,3 In this study patients of three families diagnosed with congenital superior oblique palsy have been studied. According to their family trees, a theory about the genetic transfer of this disease has been proposed and the results obtained have been compared to those reported in literature.

2MATERIAL AND METHODS

This study has been conducted on three families at Shiraz Medical University eye clinics from 1995–2002. Each patient came to the clinic with a history of eye deviation and head tilt, and after being diagnosed with congenital superior oblique palsy, (considering the fact that in these patients’ families there were people suffering from eye deviation and tilting of the head), all members of these patients’ families were invited for eye examination. All family members recieved thorough eye examinations. According to “Alternate Prism Cover” and “three step” test results superior oblique palsy was diagnosed. The main findings included; hypertropia of the affected eye in primary position, increased hypertropia in adduction and increased hypertropia in tilting the head towards the affected eye. Superior oblique palsy was considered congenital when the patient had a history of symptoms from early childhood and no history of significant incidents such as severe blows to the head existed.

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Figure 1. Pedigree of family A, B & C.

3RESULTS

Figure-1A shows three consecutive generations of “Family A”. There were no marriages between close relatives in this family. According to the history and existing pictures, patient no.4 also always tilted her head to the right, but she was not available for eye examinations. She probably suffers from congenital superior oblique palsy of the left eye. In both Patient no.1 & 2 children eye deviation and tilting of the head to the right existed before they were one year old. Both children suffered from congenital superior oblique palsy of the left side and were otherwise normal. Both underwent left inferior oblique surgery at the age of five and three respectively. The father of these children (patient no. 3) is now 40 years old. He underwent surgery of his left 30 years ago. According to old photographs, he suffered from hypertropia of the left eye and tilting of the head to the right in childhood and now has 5 prism diopter hypertropia of the left eye which increases with tilt of the head to the left and gaze to right. All these observations are infavor of congenital superior oblique palsy of the left eye.

Figure-1B shows three consecutive generations of “Family B”. None of the marriages in this family were between close relatives. According to the history and available photographs, patient no.4 tilted his head to the left all throughout his life. He was not available for eye examinations but probably suffers from congenital superior oblique palsy of the right eye. Patient no.1 has been tilting his head to the left since childhood. He showed 10 prism diopter hypertropia, of the right eye in primary position. Hypertropia of the right eye increases with gaze to left and tilt to the right. He suffers from congenital superior oblique palsy of the right eye. Patient no.2 is a 34 year old woman, She had been tilting her head to the right since childhood. She suffers superior oblique palsy of the left eye. Surgery was suggested to these two patients but because they did not accept, none of them were operated on. According to available photographs, patient no.3 has an obvious head tilt to the left and this condition has existed since childhood. He was not available for eye examinations. He probably suffers from congenital superior oblique palsy of the right eye. Patient no.5 is a 7 year old girl. She was brought to the ophthalmologist at the age of five due to tilting of the head to the left from early childhood. She showed 8 prism diopter hypertropia in primary position. Hypertropia of the right eye increased with gaze to left and tilting of the head to the right. She was diagnosed as congenital superior oblique palsy of the right eye, and underwent right inferior oblique weakening. Nothing abnormal besides eye deviation was observed in the patients of “Family B” and none of them had a history of severe blows to the head.

Figure-1C shows three consecutive generations of “Family C”. None of the marriages in this family were between close relatives. The mother of the family and her daughter suffer from superior oblique palsy of the left side. None of them have a history of severe blows to the head. Patient no.2 came to the clinic in early childhood complaining of tilting of the head to the right. In primary position she shows 10 hypertropia of the left eye which increased with gaze to right and tilt of the head to the left. Inferior oblique muscle of her left eye was overactive. She was diagnosed as congenital superior oblique palsy of the left eye and underwent inferior oblique weakening surgery of the left eye. Patient no.1 is a 44 year old woman. She has been tilting her head to the right since childhood. She shows 16 prism diopter hypertropia of the left eye. Hypertropia of the left eye increases with gaze to right and tilt to the left. She was diagnosed as congenital superior oblique palsy of the left eye, and surgery was suggested to her but she did not accept it. The father of

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patient no.2, three sisters and a brother underwent eye examinations and were all healthy. None of the parents and siblings of patient no.1 had a history of tilting the head.

The characteristics of the eight patients examined in these three families have been summarized in table 1. Also one person in “Family A” and two people in “Family B” with a lifelong history of tilting their heads were not examined. These three people also probably suffer from congenital superior oblique palsy.

Of the eight patients examined, four of them were operated on by the authors of this article. All these patients showed an over action of inferior oblique muscle in examinations prior to surgery, and in the Knapps classification were placed in class one or three. In all patients traction test of the superior oblique muscle tendon was done during surgery which showed no sign of marked laxity in any of them, therefore inferior oblique weakening was done in all patients. The degree of vertical deviation after surgery in all patients was at an acceptable level and tilting of the head was significantly reduced or eliminated.

4DISCUSSION

About 50 percent of all cases of superior oblique palsy are of the congenital type.4 Different theories have been suggested about the location of the lesion causing congenital superior oblique palsy. In some early studied nuclear aplasia of the fourth nerve is proposed as the cause of the disease. Fink and Helveston are of the opinion that most cases of superior oblique muscle palsy are due to a peripheral cause. In a study of 34 patients, six were seen to lack the superior oblique muscle tendon.3

In the current study, most of the patients were female and left eye involvement was seen more commonly; the results are comparable to that of Harris et al.2 All of our patients had unilateral involvement, in two families, left sided involvement was seen, and in one family, involvement of both right and left side was seen. In the 11 families previously reported in literature, in 8 families, unilateral involvement was seen and in 4 families only the left side was involved.2,3 Therefore in this regard the results of this study is comparable to previous reports, and it seems reasonable to conclude that the majority of cases of congenital superior oblique palsy are unilateral. Taking into view the incidence of the disease in consecutive generations, the equal involvement of males and females, the transmission of disease from father to son and the absence of consanguineous marriages in these two families an autosomal dominant pattern of inheritance of the disease seems very probable in family A&B. In “Family C”, due to the presence of only two cases in two consecutive generations, we cannot draw any definite conclusions regarding their inheritance pattern, but in spite of this, the inheritance pattern is explained with the autosomal dominant pattern. In most previous studies an autosomal dominant pattern of inheritance was also suggested.

Severe laxity or the absence of the superior oblique muscle tendon was not seen in any of our patients undergoing surgery. Therefore we are of the opinion that the cause of superior oblique muscle palsy in our patients was a neurological cause rather than being due to lesions of the superior oblique muscle tendon. Giangiacomo and Botelho have reported the bilateral absence of the superior oblique muscle in one of their patients.2 This patient belonged to a family in which almost all patients in this family had bilateral involvement, but in our series. All the patients in the involved families had unilateral lesions. It seems accurate to conclude that different genetic lesions with different effector sites can cause congenital superior oblique palsy.

5CONCLUSION

In this current study and previous series, an autosomal dominant inheritance pattern is seen. On this basis, it seems necessary to consider the presence of genetic inheritance, in any patient presenting with congenital superior oblique palsy. A thorough examination of family members of these patients, will enrich our medical knowledge in this field.

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REFERENCES

1.Bhola, R.M., Horne, G.V., Squirrell, D.M., Chan, T.K., Kumar, D. Autosomal dominant congenital superior oblique palsy. Eye 2001; 15: 479–484.

2.Botelho, P.J., Glangiacoma, J.G. Autosomal dominant inheritance of congenital superior oblique palsy. Ophthalmology 1996; 103: 1508–1511.

3.Harris, D.J., Memmen, J.E., Katz, N.N.K., Parks, M.M. Familial congenital superior oblique palsy. Ophthalmology 1986; 93: 88–90.

4.Younge, B.R., Sutula, F. Analysis of trochlear nerve palsies, diagnosis, etiology and treatment. Mayo Clin Proc 1977; 52: 11–18.

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