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)

4. 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.

5. MED Syndrome causes

6. 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

7. Pathology : Ziffer classification
• Type 1 includes patients with primary IR restriction or fibrosis
• 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.

8. • 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.

9. 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.

10. 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.

11. 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.

12. 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 .

13. 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 .

14. 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

15. 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 .

16. • 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 .

17. • 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.

18. 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.

19. • 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.

20. • 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.

21. 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.

22. • 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.

23. 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.

24. • 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.

25. D/D :

26. 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.

27. 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.

28. 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.

29. • 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 preferred.

31. • 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 .

32. • 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.

33. • 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.

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

35. • 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

36. 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.

37. 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.

38. • 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.

39. • 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.

40. IN Summary ………

41. 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 .