Double Elevator Palsy refers to limited elevation of one eye in adduction, primary gaze, and abduction. The term double elevator refers to both the elevators of an eye i.e. superior rectus and inferior oblique muscle. However, there are cases in which deficient elevation is produced by tight inferior rectus muscle. Due to this, Double elevator palsy is included under restrictive strabismus. Now Double elevator palsy is known by a more descriptive term as Monocular Elevation Deficit Syndrome (MED).This is distinguished from Brown’s syndrome in which elevation is restricted much more in adduction rather than in abduction.
This condition presents as hypotropia when the patient fixates with normal non-paretic eye. Chin elevation and ptosis/pseudoptosis are often present. Fixation with the paretic eye produces hypertropia of the normal non-paretic eye. Ptosis also disappears since it is not due to paresis of levator palpebrae superioris muscle.
White (1942) described a congenital deficiency of upgaze associated with hypotropia and ptosis of the affected paretic eye. Dunlap (1952) to describe the weakness affecting both elevators of involved eye coined the term Double elevator palsy.
Double elevator palsy may be associated with certain innervational conditions such as
Lorenz Brigit, Brodsky Michael C. Pediatric Ophthalmology, Neurophthalmology, Genetics; Strabismus-New Concepts in Pathophysiology, Diagnosis, and Treatment. Springer- Verlag Berlin Heidelberg 2010. P 87- 88.
Kaynak-Hekimhan Pelin, Grover A K, Toukhy Essam El, Nassaralla Belquiz A, Murthy Ramesh, Morekar Sunil. Surgical Techniques in Ophthalmology- Oculoplasty and Reconstructive Surgery. Jaypee Brothers Medical Publishers (P) Ltd 2010. P 219.
White JW. Paralysis of the superior rectus and inferior oblique muscles of the same eye. Arch Ophthalmol. 1942; 27: 366–371.
Dunlap EA. Vertical displacement of horizontal recti; Symposium on strabismus transactions of the new Orleans Academy of Ophthalmology; St Louis: Mosby; 1971. pp. 307–329.
Symptoms of MED includes
Causes may include congenital and acquired cases.
Congenital cases are characterised by orthotropia or hypotropia in primary position of gaze, true ptosis or pseudoptosis in majority of cases. A large number of cases on forced duction test, show restriction of eyeball in elevation. Jaw movement as in yawning may show paradoxical movements of eyelids (Marcus Gunn phenomenon). Dissociated vertical deviation (DVD) may be present. Upward and outward rolling of eyeballs or Bell’s phenomenon is often preserved.
Since elevation is preserved in Bell’s phenomenon, DVD or under anaesthesia, several authors believe it to be a supranuclear disorder. Others discuss it to be a fascicular lesion. Long lasting palsy of superior rectus alone may impede elevation in adduction, thus nuclear origin of superior rectus may be a factor. Even primary fibrotic origin is presumed in cases showing resistance to forced duction test.
Thus supranuclear, nuclear, fascicular and muscular causes are discussed for double elevator palsy.
Cerebrovascular diseases such as hypertension, thromboembolism, and arteritis usually cause acquired cases. Other causes of double elevator palsy include
Diagnosis depends upon history and clinical examination.
In congenital MED, history of onset of symptoms and its association with other features is important. The presence of associated amblyopia points to congenital aetiology.
In acquired MED, history of associated neurological features (ataxia, vertigo, tinnitus, loss of consciousness) is important. History of malignancy or cardiovascular disorder is also important.
Clinical examination distinguishes between MED due to primary superior rectus palsy, any cause of supranuclear superior rectus weakness, or primary/secondary inferior rectus restriction.
Primary superior rectus palsy or paresis: It is characterised by a forced duction test showing no restriction to full upward rotation. Bell’s phenomenon is not present.
Supranuclear superior rectus weakness: This is usually congenital and is characterised by monocular absence of vertical eye movements in superior field of gaze. There is no resistance to upward gaze in forced duction test. Bell’s phenomenon is present.
Patients with primary inferior rectus restriction or fibrosis: This group of patients often do not have hypotropia in primary gaze. Forced duction test shows restriction to upward rotation because of inferior rectus restriction. Superior rectus palsy or supranuclear disorders may produce secondary contracture in inferior rectus. Hypotropia and ptosis are usually present. Forced duction test shows inferior rectus restriction.
Besides regular blood tests, following tests may be done
Differential diagnosis of congenital MED includes conditions such as
Differential diagnosis of acquired MED includes conditions such as
Management is not required in all cases of MED.
Patients with orthophoria in primary position of gaze or with limited changes in head position may be just observed.
Indications for surgery are
Patient and the family members should be clear that surgery does not cure MED, particularly cases with superior rectus paresis or with supranuclear aetiology. The goal of surgery is to improve position of affected paretic eye in primary position of gaze, to improve binocularity.