The Superior Oblique Posterior Tenectomy as therapy for Congenital Brown’s Syndrome

Introduction: Since more than 50 years, various surgical procedures
have been described for congenital Brown’s syndrome. However most
showed low success rates and some even severe side effects. The aim
of this retrospective study was to evaluate the results of superior
oblique posterior tenectomy. This technique was introduced in 1996
by Mühlendyck. Since this first description no other results have
been published by others. Patients and methods: 21 patients with
congenital Brown’s syndrome (aged 2 to 29 years) were operated
between 2001 and 2006, in the Department of Ophthalmology,
Ludwig-Maximilians-University Munich. In all patients,
intraoperative forced ductions showed severe passive restriction of
elevation in adduction and superior oblique posterior tenectomy was
performed as a primary procedure. The squint angle (vertical and
horizontal deviation in primary position, lateral gaze, up/down
gaze), active elevation in adduction, abnormal head posture at
distance fixation, binocular vision (in primary position and
anomalous head posture) were assessed in each case. All the
measurements were performed 1 day before, 1 month and 3 months
after surgery. Eight patients were examined 6-24 months after
primary procedure. Results: Intraoperatively, a tight or very tight
posterior part of the superior oblique tendon was found in 87 % of
operated eyes. At the end of the operation, passive motility in
adduction became free (14 eyes) /almost free (7 eyes) on the
majority of operated patients (totally 23 eyes). Inspite of free
passive motility, the active monocular elevation in adduction was
only slightly improved by 0.5 mm to 5 mm (mean 2.25 mm), like
hypotropia in primary position, which was improved by 1 to 12 deg
(mean 4 deg). Better results regarding hypotropia in primary
position were noted when the preoperative vertical deviation in
primary position was more than 10 deg. However in cases with
preoperative hypotropia less than 10 deg, a better fusion was
obtained. Preoperatively, 17 patients showed an abnormal head
posture. Postoperatively, 12 of them totally gave up their posture
and 5 improved partially. Of 8 cases with a long-term follow-up, 5
showed unchanged measurements of vertical deviation in primary
position, monocular elevation in adduction and head posture. 3
patients with a long-term follow-up had further surgery and an
improvement of vertical deviation in straight gaze and active
elevation in adduction. Conclusion: The use of superior oblique
posterior tenectomy significantly improves abnormal head posture
and also improves alignment and ocular rotations in patients with
congenital Brown’s syndrome. We did not see any serious side effect
like consecutive superior oblique muscle underaction (as in
superior oblique tenotomy or recession) and no foreign body
extrusion (as in silicone superior oblique tendon expander). So the
superior oblique posterior tenectomy is a safe and effective
procedure with regard to the head posture. The fact that the
passive motility had dramatic improved postoperatively, but the
active elevation in adduction improved only slightly, suggests a
paretic/ dysinnervational component to the superior oblique in some
patients. From this point of view, a therapeutic algorithm
depending on intraoperative/ radiological findings in congenital
Brown’s syndrome is proposed.