Double elevator palsy

MED SYNDROME , CAUSES, ETIOLOGY
INVESTIGATIONS
CLINICAL sings & symptoms etc

1. DOUBLE ELEVATOR PALSY ( MED : MONOCULAR ELEVATION DEFICIENCY SYNDROME) Dr. VINIT KUMAR SCEH, LAHAN, NEPAL PEDIATRIC OPHTHALMOLOGY

2. Monocular Elevation Deficiency, also known by the older term Double Elevator Palsy , is an inability to elevate one eye in all fields of gaze, usually resulting in one eye that is pointed downward relative to the other eye (hypotropia)

3. Disease Monocular Elevation Deficiency (MED) is the limitation of elevation of the affected eye from any position of gaze with normal ductions in all other gazes. MED is a frequent cause of hypotropia & can be associated with ptosis/pseudoptosis. Superior rectus palsy, inferior rectus restriction & supranuclear lesions have been found to be contributory to MED.

4. MED Syndrome causes

5. Etiology : congenital (mostly sporadic) & acquired Congenital causes of MED include, supranuclear palsy, primary superior rectus (SR) paresis & primary inferior rectus(IR) restriction as in cases of congenital fibrosis of inferior rectus . Acquired MED is usually caused by trauma, cerebrovascular diseases like hypertension, thromboembolism, sarcoidosis, syphilis & midbrain tumors like pineocytomas, acoustic neuromas & metastatic tumors affecting supranuclear pathways

6. Pathology : Ziffer classification Type 1 includes patients with primary IR restriction or fibro sis Forced duction test (FDT) demonstrates a tight IR. The upward saccades are usually normal until stopped by tight IR , preventing further upgaze . Bells phenomenon is usually poor. In Type 2 MED , cases of primary SR palsy are included. FDT is free & upward saccades are slow both below & above midline. Bell’s phenomenon is usually absent.

7. Type 3 MED is supranuclear type & is usually congenital. It is characterized by intact or mildly reduced vertical saccadic velocity below midline but abnormal or absent velocity above midline & FDT is free.

8. Pathophysiology It has been established that superior rectus is the main muscle responsible for elevation of the eye, be it in abduction, adduction or primary position. Thus, the defective elevation can be explained by presence of a superior rectus palsy alone, inferior rectus restriction can also be considered as a cause of MED in presence of a normal superior rectus.

9. Pathophysiology : Efferent tracts for upgaze leave the rostral interstitial nucleus of the medial longitudinal fasciculus ( riMLF ), cross the midline in the posterior commissure, course through the pretectum & enter the superior rectus (SR) subnucleus of the oculomotor nucleus, leaving the subnucleus , upgaze fibres to the SR immediately cross the midline again. As a result of double decussation of upgaze fibers, the SR receives innervation from ipsilateral riMLF as well as contralateral pretectum & SR subnucleus . In cases of MED, it is presumed that supranuclear input from riMLF into third cranial nerve nucleus is interrupted. Supranuclear deficiency affects upgaze , therefore causes monocular elevation deficiency.

10. Clinical feature Age: Average age of presentation is 14 years as reported in previous studies. Gender: No gender predisposition Vertical deviation , head posture , diplopia & ptosis BINOCULAR FIXATION : patient keep their head tipped backward & maintain binocular fusion , visual acuity is normal in this patients . The posture adopted by these patients to move the eyes by means of Dolls head phenomenon in to the field of action of the depressors of the globe.

11. Clinical features : However when these patients hold their head erect in primary position their may occure : hypotropia of the affected eye & vertical diplopia . Fixation with uninvolved eye : shows hypotropia in involved eye . Pseudoptosis ( that is ptosis disappears when the patient fixates with the paretic eye ) . True ptosis due to associated LPS weakness may be present in 50% of cases . True ptosis does not resolve when patient fixates with paretic eye . Amblyopia of the affected eye with visual acuity of 6/60 or less Diplopia is absent .

12. Chief Complaints Vertical misalignment of the eyes Diplopia Abnormal head posture Inability to elevate the affected eye Drooping of eyelid Decrease vision Fixation with involved eye : shows following features : hypertropia of normal eye which is greater due to secondary deviation , visual acuity in the normal eye may be reduced , & true ptosis due to associated weakness of LPS may be present .

13. CLINICAL FEATURES : Limitation of elevation ( in adduction as well as abduction, both on version & ductions ) beyond midline is main characteristic of this condition . Other clinical characteristics : An extra or deep lower lid fold on the affected side may be seen in patients with IR muscle restriction. Bells phenomenon : is poor / absent with IR muscle restriction . Positional tonometry : with applanation tonometer shows a rise in IOP of more than 3mm Hg in 15 degree upward gaze as compared to that in primary gaze in patient with restrictive limitations . But no such significant increase in IOP occurs in paretic weakness

14. Signs Ptosis/Pseudoptosis : Ptosis can be associated with hypotropia because of fascial attachments between levator palpebrae superioris & superior rectus muscle.. Pseudoptosis & true ptosis both the components can be present in the patient. In these cases when the patient is made to fix with the affected eye, ptosis partly recovers. True ptosis when present is usually complex type & is associated with Marcus Gunn Jaw Winking phenomenon (MGJWP). Amblyopia may be present if there is a constant deviation of affected eye or associated ptosis, or anisometropia .

15. Abnormal Head Posture  : Most commonly patient has a chin elevation if binocular fusion is present. Abnormal head posture may not be present if the affected eye is amblyopic. Upward Saccades : Upward saccades are slow/floating in cases of SR palsy, absent above the midline in supranuclear palsy & intact (coming to an abrupt halt) in cases associated with IR restriction .

16. Bell’s phenomenon is usually absent in cases of IR restriction & SR palsy as they limit the upward rotation of globe, but Bell's is usually present in cases of MED resulting from supranuclear defects . Deviation : There is hypotropia of the affected eye when the normal eye is fixing , but as the affected eye takes up fixation there is hypertropia of the normal eye . MED cases may also have co-existent horizontal deviations.

17. Diagnostic procedures Forced duction test Forced duction test is a clinical test which should be done pre-operatively to reveal any restriction. The test is typically performed under topical anaesthesia , conjunctiva is held at limbus with Pierce Hoskin forceps or globe holding forceps, & patient is asked to look in opposite direction of testing muscle to relax the concerned muscle . A positive Forced Duction Test (FDT) is seen in patients of IR restriction.

18. Active Force Generation Test Active force generation test is done under topical anaesthesia by asking the patient to look in the direction of muscle being tested, presence of a tug is suggestive of residual SR action.

19. Diplopia Charting Red & green glasses over right & left eyes respectively, dissociate the two images & would be seen double. Test can be done both for distance & near, with the help of illuminated slit target. The slit is used vertically for charting horizontal deviations & horizontally for charting vertical deviations. The seperation between two images is recorded & is useful in diagnosis & follow-up.

20. Hess Screen & Lees Screen Hess Screen & Lees Screen is used to document relative incomitance & underactions & is based on haploscopic principle. Two test objects are shown to the patient which is seen as one localisation . Hess Screen consist of a three and a half feet black cloth marked with a series of red lines forming a square of 5 degree each. From the central zero point three squares 15 degree marks the inner square and outer square has excursion of 30 degree.

21. The outer square is used for mild incomitances not detected on inner square charting. Patient wears a red green glass, with red glass in front of right eye and green glass in front of left eye, patient is given a green pointer which he aligns on the red dots and the observer records the points. Lees Screen is also similar but does not require red green glass instead uses a mirror septa to cause dissociation of two eye.

22. Differential diagnosis Brown’s Syndrome is characterised by limitation of elevation in adduction, with divergence in upgaze caused by slippage of globe resulting in characterstic Y pattern . Vertical Duane Syndrome can be diagnosed by the presence of globe retraction in downgaze along with limitation of elevation in upgaze . Congenital fibrosis of extra ocular muscles initially affecting inferior recti can be misdiagnosed as MED. …….Bilateral presentation involvement of other extraocular muscles are features that help distinguish it.

23. Partial third nerve palsy involving the superior division of oculomotor nerve may simulate the findings of MED. Progressive external ophthalmoplegia involves multiple extra ocular muscles. Orbital inflammatory disease and orbital cellulitis present with a tender inflamed globe.

24. D/D :

25. Management Management of MED includes both non-surgical & surgical components. Non-surgical management The correction of underlying refractive error is to be done & amblyopia therapy is given if needed, followed by surgery whenever indicated.

26. Indications of surgery ?? ?? Which include ……. Significant vertical deviation in primary gaze Significant abnormal head posture/ AHP Deviation-induced amblyopia Diplopia in primary gaze, & restricted binocular fields.

27. GOAL OF SURGERY … The goal of surgery is to improve the position of the affected eye in primary gaze & to increase binocular field of vision. The surgery of choice in the management of monocular elevation deficit depends on results of forced duction test . FDT In patients with positive forced duction test, inferior rectus recession is the first choice of management.

28. In patients with negative forced duction test but a positive active force generation test, superior rectus resection can be done. In patients with negative FDT /forced duction test & a negative active force generation test /ATGT Knapp's procedure is preferr ed.

29. Knapp's procedure Knapp’s procedure is commonly practiced & is now a well-established treatment for MED syndrome . In the Knapp’s procedure, the tendons of the medial & lateral rectus muscles are transposed to the insertion of the superior rectus muscle. Knapp’s in his work studied 15 patients over a period of eight years . The procedure showed marked variability correcting 21-55 PD (average 38 PD) hypotropia .

30. Modifications of Knapp's procedure For management of MED cases with associated horizontal deviation partial tendon Knapp’s ( Modifed Knapp’s) procedure has been described, in which the superior part of equally divided horizontal muscles is placed near the superior rectus muscle insertion, allowing the correction of horizontal deviation with the untouched inferior half.

31. Augmented Knapp's procedure, Knapp's procedure can be combined with posterior fixation sutures on the horizontal recti, known as Augmented Knapp's. Following the surgical correction of hypotropia & improvement in Bell’s phenomenon, associated ptosis and/or Marcus Gunn phenomenon be addressed.

32. Contralateral superior rectus recession Contralateral superior rectus recession can be an option of management in the patients with residual hypotropia after inferior rectus recession.

33. Modified Nishida's for monocular elevation deficit / MED syndrome No split no tenotomy technique by Nishida et al has originally been described for abducen nerve palsy, the procedure has been found to be useful in the management of monocular elevation deficit by Murthy et al and can help in correction of upto 30 pd of vertical deviation with low risk of anterior segment ischemia

34. Management of Acquired MED As there are wide variety of causes of acquired MED, thorough investigations (general, ophthalmologic, neurologic, neuro-ophthalmologic & orthoptic (ocular motility work up) should be undertaken, & management varies according to the underlying cause.

35. Complications Ptosis can lead to refractive error & amblyopia, also if ptosis surgery is done before the strabismus surgery it can lead to exposure keratopathy as most of the patients have poor Bell's phenomenon . Surgical complications : Anterior segment ischemia : presenting with corneal edema, thinning, non pigmented keratin precipitates, iris atrophy & anterior chamber flare. Anterior segment ischemia can result if three or more adjacent recti surgery has been done in one eye, adults with atherosclerosis, previous radiation therapy & retinal detachment surgery are more vulnerable.

36. The complication can be avoided if two vertical recti along with one horizontal recti are not operated in the same sitting. Management includes, systemic & local corticosteroid . Overcorrections & undercorrections . Tenon's prolapse & conjunctival cyst can result due to improper apposition of the conjunctiva which allows Tenon's to prolapse & interferes with healing process.

37. Corneal dellen formation can occur due to disruption of tear film & local dehydration. Other intraoperative complications like surgery on wrong eye, wrong muscle, hemorrhages , scleral perforation,slipped muscle, bradycardia, infections may also occur in patients undergoing surgery.

38. IN Summary ………

39. Points to remember Recession of IR muscle : useful for presence of inferior restriction for a vertical deviation up to 18-20 D Recession of the IR muscle plus resection of SR is indicated when in the presence of inferior restriction & the deviation is more than 18 to 20 D KNAPPS procedure usually corrects 20 to 35 PD of hypotropia in primary position. Knapp after IR recession usually has greater effect Augmented transposition using posterior fixation suture should be done for large hypotropia > 35 PD with no IR restriction Modified Knapp’s : if horizontal deviation is present then recess- resect & also transpose the MR & LR muscles .