Convergence Paralysis & Spasm Flashcards
What is convergence paralysis?
An inability to converge (unlike in convergence paresis where some convergence is possible)
What are the signs and symptoms of convergence paralysis?
- Crossed diplopia at middle to near
- Exotropia at near
- Possible involvement of accommodation and pupils
What aetiology is there in convergence paralysis?
- Head trauma
- Neurological disease such as encephalitis or MS
- May be associated with dorsal midbrain syndrome – Parinaud’s syndrome (Feroze and Bhimji, 2017)
- May be primary
- Functional overlay/psychogenic (test BO fusional amplitude in the distance)
How do we manage convergence paralysis?
- Investigations e.g. MRI scan
- Base in prisms
- Occlusion
- Convex/hypermetropic lens (if accomm affected)
- Referral for psychological/psychiatric assessment (if functional overlay)
What is convergence spasm?
Usually spasm of near reflex due to contraction of MR muscles and contraction of ciliary muscles
What are the symptoms of convergence spasm?
- Uncrossed Diplopia
- Blurred Vision (if also having accommodation spasm)
What are the signs of convergence spasm?
- Esotropia - could be variable in size (from extra accomm, variable ET when measuring)
- Miosis
- Observe consistency of convergence spasm and miosis throughout testing
- Spasm on lateral gaze gives appearance of LR palsy - test abduction fully (can we get them fully abducted), doll’s head (to differentiate between convergence spasm and LR palsy)
- Macropsia
- Pseudo myopia (because they’re over accommodating so much)
What did Hyndman (2017) find was the most common cause of convergence spasm (spasm of the near reflex)?
Head Injury
What is the aetiology of convergence spasm?
- Head Injury
- Functional (stress & anxiety)
Should observe or do dynamic RET to see if there is an accommodation spasm also present - Neurological Disease
Encephalitis
MS
Arnold Chiari malformation
Tumours (posterior foss, pituitary)
Cerebral aneurysm (Weber et al., 2008) - Following CI exercises (ensure they relax after doing them because otherwise you can induce a convergence spasm)
How do we manage convergence spasm?
- Avoid treatment
If someone understands what is happening with their eyes they may be able to better control what is happening. See them again in 6 - 8 weeks. - Botulinum toxin (Kaczmarek et al., 2009)
There’s limited success but some find this useful - Occlusion
- Atropine with convex lenses
- Refer for psychological/psychiatric assessment
- Refer for neurological investigation if appropriate
How do we differentiate between CNVI palsy and convergence spasm?
- Lateral gaze measurements
- Spasm has variable measurement
- Spasm have full abduction on Dolls Head
- Spasm have normal saccades
- Hess Chart
What systemic drugs can we give a patient with convergence spasm?
Baclofen
What topical drugs can we give a patient with convergence spasm?
Given atropine 2 - 3 times a day and then weaned onto cyclo as it induces the need to converge to focus
Use miotics e.g. Pilocarpine, these increase depth of focus and reduce drive to converge
If someone had an accommodation to a level much worse than expected for their age, how can we test if this is genuine?
Dynamic RET (don’t tell them what you’re looking for)
- Autorefraction
When accommodation is reduced the patient may stop converging at the point where the image blurs. How can we test if there is an associated convergence issue?
Put up some low plus lenses to relax accommodation as the glasses do it for them.
If a patient is giving up converging because of blur and you can prove this by redoing convergence with the plus lenses then you know it’s just an accommodation issue and not a true convergence one. If it doesn’t help however = convergence issue
