11 - Vertical Deviations Flashcards

Question

# (Superior oblique muscle overaction) Techniques pour weaken un superior oblique tendon?

Answer 1

Weaken the superior oblique tendon : * Recession * Tenotomy * Tenectomy * Lengthening by insertion of a silicone spacer or nonabsorbable suture or by split- tendon lengthening

Answer 2

Oui. Significant intorsion will also be reduced with any of these procedures.

Answer 3

The most common paralysis of a single cyclovertical muscle is fourth nerve (trochlear) palsy, which involves the superior oblique muscle.

Answer 4

The palsy can be **congenital or acquired**; if the latter, it is usually a result of **closed head trauma** or, less commonly, **vascular problems of the central nervous system, diabetes mellitus, or a brain tumor**. Direct trauma to the tendon or the trochlear area is an occasional cause of unilateral superior oblique muscle palsy.

Answer 5

Results of one study showed that most patients with congenital superior oblique palsy had an **absent ipsilateral trochlear nerve** and **varying degrees of superior oblique muscle hypoplasia**.

Answer 6

Vrai. Superior oblique muscle underaction can also occur in several craniofacial abnormalities.

Answer 7

To differentiate congenital from acquired superior oblique muscle palsy : * The clinician can examine childhood photo graphs of the patient for a **preexisting compensatory head tilt**, although manifestations of congenital palsy sometimes become apparent only later in life. * The presence of a **large vertical fusional amplitude** supports a diagnosis of **congenital** superior oblique palsy, whereas associated **neurologic disorders** suggest an **acquired** condition. * **Facial asymmetry from long- standing** head tilting indicates **chronicity**.

Answer 8

Diagnostic evaluation, including neuroimaging, often fails to identify an etiology but may still be warranted for acquired superior oblique palsy without a history of trauma.

Answer 9

Either the normal or the affected eye can be preferred for fixation.

Answer 10

Examination of versions usually reveals * Underaction of the involved superior oblique muscle * Overaction of its antagonist inferior oblique muscle /!\ The action of the superior oblique muscle can appear normal.

Answer 11

* In a unilateral palsy, the hyperdeviation is **typically incomitant**, especially in the acute stages. * **Over time, contracture of the ipsilateral superior rectus or contralateral inferior rectus muscle** can lead to “spread of **comitance**,” with the result that there is minimal difference in the magnitude of the hypertropia when the patient looks from one side to the other.

Answer 12

If depression cannot be evaluated because of the eye’s inability to adduct (ex. in third nerve palsy), superior oblique muscle function can be evaluated by **observing whether the eye intorts**, as judged by the movement of surface landmarks or examination of the fundus, **when the patient attempts to look downward and inward from primary position**.

Answer 13

* Weakness of the superior oblique muscle also results in **extorsion** of the eye. * If the degree of extorsion is large enough, subjective incyclodiplopia, in which the patient describes the image as appearing to tilt inward, can occur. Action de l'oblique supérieur : dépression, intorsion et abduction Donc weakness : élévation, extorsion et adduction

Answer 14

* The diagnosis of unilateral superior oblique muscle palsy is further established by results of the **3- step test** and the **double Maddox rod test** to measure torsion. * However, results of the 3- step test can be confounded in patients with DVD, entities involving restriction, additional paretic muscles, previous strabismus surgery, or skew deviation. * Intorsion of the higher eye on fundus examination— instead of the expected extorsion— suggests skew deviation, especially when there are associated neurologic findings. * In addition, if the patient is placed in a supine position, the vertical tropia is more likely to decrease with skew deviation than with superior oblique palsy.

Answer 15

* Patients who **fixate with the paretic eye** can exhibit so- called inhibitional palsy of the contralateral antagonist. * If a patient with right superior oblique palsy uses the right eye to fixate on an object that is located up and to the left, the **innervation of the right inferior oblique muscle** required to move the eye into this gaze position **is reduced** because the right inferior oblique muscle does not have to overcome the normal antagonistic effect of the right superior oblique muscle (**Sherrington’s law**). * According to **Hering’s law**, **less innervation is also received by the yoke muscle** of the right inferior oblique muscle, which is the left superior rectus muscle. * This decreased innervation **can lead to the impression that the left superior rectus muscle is paretic**.

Answer 16

Bilateral superior oblique palsy occurs commonly after head trauma but is sometimes congenital.

Answer 17

Unilateral Superior Oblique Palsy : * Shows little if any V pattern and less than 10° of extorsion in downgaze. * Subjective incyclodiplopia is uncommon. * The Bielschowsky head-tilt test (step 3 of the 3- step test) yields positive results for the involved side only. * Abnormal head positions— usually a tilt toward the shoulder opposite the side of the weakness— are common. * The oblique muscle dysfunction is confined to the involved eye. Bilateral Superior Oblique Palsy : * Usually show a V pattern. * Extorsion is 10° or more in downgaze; more than 15° of extorsion in primary position is highly suggestive of bilateral involvement. * Subjective incyclodiplopia is common in acquired bilateral cases. * The Bielschowsky head- tilt test yields positive results on tilt to each side— that is, right head tilt produces a right hypertropia and left head tilt, a left hypertropia. * There is bilateral oblique muscle dysfunction. * Patients may exhibit a chin- down head position. * Symmetric palsies may show little or no hypertropia in primary position.

Answer 18

**Markedly asymmetric bilateral** superior oblique palsy that initially appears to be unilateral is called masked bilateral palsy.

Answer 19

Signs of masked bilateral palsy include * Bilateral objective fundus extorsion * Esotropia in downgaze * Even the mildest degree of oblique muscle dysfunction on the presumably uninvolved side

Answer 20

Masked bilateral palsy is more common in patients with head trauma.

Answer 21

Indications for surgery : * Abnormal head position * Significant vertical deviation * Diplopia * Asthenopia

Answer 22

**For small, symptomatic deviations** that **lack a prominent torsional component** — especially those that have become **comitant**— prisms that compensate for the hyperdeviation in primary position may be used to overcome diplopia.

Answer 23

If the paresis is asymmetric, hypertropia in primary position may be present and require many of the same considerations as hypertropia in unilateral palsy.

Answer 24

If the palsies are symmetric (minimal hypertropia in primary position), **both inferior oblique muscles can be weakened** if they are **overacting** and **hypertropia is present in side gaze**. **Bilateral superior oblique muscle tightening** should be performed when hypertropia in side gaze is **accompanied by V-pattern esotropia or symptomatic extorsion,** especially in downgaze.

Answer 25

Most cases are considered to be congenital or posttraumatic.

Answer 26

Inferior oblique palsy is suspected when the patient has **hypotropia and 3- step- test results** consistent with this diagnosis. Prominent feature is **deficient elevation when the eye is in adduction**.

Answer 27

* Indications for treatment of inferior oblique muscle palsy are abnormal head position, vertical deviation in primary position, and diplopia. * Management consists of weakening either the ipsilateral superior oblique muscle or the contralateral superior rectus muscle.

Answer 28

* Skew deviation is an **acquired vertical strabismus** that can mimic superior or inferior oblique palsy. * The deviation is due to **peripheral or central asymmetric disruption of supranuclear input from the otolith organs. **

Answer 29

* **Intorsion of the hypertropic eye** on fundus examination— rather than the expected extorsion in superior oblique palsy— suggests skew deviation, particularly when there are associated neurologic findings. * In addition, if the patient is **placed in a supine position, the vertical tropia is more likely to decrease with skew deviation** than with superior oblique palsy. * Similarly, if there is **extorsion of the hypotropic eye** on fundus examination— instead of the expected intorsion in inferior oblique palsy— then skew deviation is the likely diagnosis.

Answer 30

Monocular elevation deficiency (previously termed double- elevator palsy) involves a limitation of upward gaze with a hypotropia that is similar in adduction and abduction.

Answer 31

There are 3 forms of this motility pattern, each with a different cause: * **Restriction of the inferior rectus muscle**; * **Deficient innervation of elevator muscles** (paresis of 1 or both elevator muscles or a monocular supranuclear gaze disorder); * **Combination** of restriction and elevator muscle deficit.

Answer 32

All 3 forms of monocular elevation deficiency are characterized by * Hypotropia of the involved eye with limited elevation * A **chin-up head position** with binocular fusion in downgaze * Ptosis or pseudoptosis

Answer 33

* True ptosis is present in **50%** of affected patients. * These are features of **third nerve palsy**, as well. * Therefore, if any other feature of third nerve palsy is present, that condition should be suspected rather than monocular elevation deficiency.

Answer 34

Restriction * Positive forced duction on elevation * Normal force generation and saccadic velocity (no muscle paralysis) * Often an extra or deeper lower eyelid fold on attempted upgaze * Poor or absent Bell phenomenon

Answer 35

Elevator muscle innervational deficit * Negative forced duction on elevation * Reduced force generation and saccadic velocity * Preservation of Bell phenomenon (indicating a supranuclear cause) in many cases * Combination of restriction and elevator muscle deficit

Answer 36

Positive forced duction on elevation * Reduced force generation and saccadic velocity

Answer 37

Indications for treatment include * A large vertical deviation in primary position, with or without ptosis * An abnormal chin-up head position.

Answer 38

* If **restriction originating inferiorly** is present, the **inferior rectus muscle** should be **recessed**. * If there is **no restriction**, the **medial and lateral rectus muscles can be transposed toward the superior rectus muscle** (Knapp procedure). * Alternatively, the surgeon can **recess the ipsilateral inferior rectus** and either **recess the contralateral superior rectus muscle** or **resect the ipsilateral superior rectus muscle**. * Ptosis surgery should be deferred until the vertical deviation has been corrected and the pseudoptosis component eliminated.

Answer 39

Ptosis surgery should be deferred until the vertical deviation has been corrected and the pseudoptosis component eliminated.

Answer 40

Faux. Diplopia in the immediate postinjury stage is common and not necessarily an indication for urgent intervention.

Answer 41

Depending on the site of the bony trauma, muscles can be either * Restricted due to entrapment * Paretic due to muscle contusion or nerve damage « Flap tears » of the inferior rectus muscle have also been described by some authors as a cause of limitation of elevation, depression, or both. Paresis of a muscle may resolve over several months. If the fracture requires surgery, the range of eye movements may improve. By contrast, fibrosis after trauma may cause restriction to persist even after successful repair of the fracture.

Answer 42

Treatment of strabismus is usually necessary when **diplopia persists in primary position or downgaze** or there is an associated **compensatory head position**.

Answer 43

Some mild limitations of eye movements can be managed with **prisms**.

Answer 44

Dissociated vertical deviation (DVD) is an **innervational disorder** found in more than 50% of patients with infantile strabismus (esotropia or exotropia).

Answer 45

Dissociated vertical deviation (DVD) is an innervational disorder found in **more than 50%** of patients with infantile strabismus (esotropia or exotropia).

Answer 46

* There are 2 explanations for the origin of DVD. * One theory is that DVD is a vertical vergence movement **to damp latent nystagmus**, with the oblique muscles playing the principal role. * An alternative theory suggests that deficient fusion allows the **primitive dorsal light reflex**, which is prominent in other species, to emerge.

Answer 47

Dissociated vertical deviation **usually presents by age 2 years**, whether or not any horizontal deviation has been surgically corrected.

Answer 48

* Either eye **slowly drifts upward and outward**, with **simultaneous extorsion**, **when occluded or during periods of visual inattention** (Fig 11-8). * Some patients attempt to compensate by **tilting the head**, for reasons that still have not been conclusively identified. In addition to DHD, latent nystagmus and horizontal strabismus are often associated with DVD. * These entities are manifestations of deficient binocular vision.

Answer 49

**DVD** is usually the most prominent component of the dissociated strabismus complex (DSC), but sometimes the principal dissociated movement is one of abduction (dissociated horizontal deviation, DHD), and occasionally it is almost entirely a torsional movement (dissociated torsional deviation, DTD).

Answer 50

* DVD is usually bilateral but is frequently asymmetric. * It may occur spontaneously (manifest DVD) or only when 1 eye is occluded (latent DVD).

Answer 51

Vrai. Measurement of DVD is difficult and imprecise.

Answer 52

* In one method, a base- down prism is placed in front of the upwardly deviating eye while it is behind an occluder. * The occluder is then switched to the fixating lower eye. * The prism power is adjusted until the deviating eye shows no downward movement to refixate. * These steps are then repeated for the other eye. * Measurements obtained with this technique are confounded by any coexisting true hypertropia, but it does provide a rough estimate for surgical planning.

Answer 53

Treatment of DVD is indicated if the deviation is **noticeable** (generally more than 6Δ–8Δ) and **occurs frequently during the day**.

Answer 54

When DVD is unilateral or highly asymmetric, **encouraging fixation by the eye with greater DVD** by optically **blurring the fellow eye** is sometimes sufficient.

Answer 55

* Surgery on the vertical muscles often improves the condition but rarely eliminates it. * **Recessions of the superior rectus muscle**, ranging from 6 to 10 mm according to the size of the hypertropia, can be effective. * If there is residual DVD after superior rectus muscle recession, **inferior rectus muscle resection or plication** can be performed. * **Inferior oblique muscle anterior transposition** is also effective in treating DVD, especially if it is accompanied by inferior oblique muscle overaction. * Bilateral surgery is performed whenever both eyes can fixate; asymmetric surgery is an option if the DVD is asymmetric.

Answer 56

Because DVD can mimic **OEAd**, distinguishing it from overaction of the inferior oblique muscles is important, as the **surgical approaches to these 2 conditions are different in most cases**.