Neuro-ophthalmology Illustrated Chapter 13 Diplopia 13 – Localization of Findings & Treatment of Diplopia – 3rd and 4th Nerves

Questions:
161. Where do these findings localize the lesion: 4th nerve palsy with contralateral Horner syndrome?
162Where do these findings localize the lesion: 3rd nerve palsy with contralateral ptosis and contralateral superior rectus weakness?
163. Where do these findings localize the lesion: 3rd nerve palsy with contralateral hemiparesis?
164. Where do these findings localize the lesion: 3rd nerve palsy and ipsilateral cerebellar ataxia?
165. Where do these findings localize the lesion: 3rd nerve palsy and contralateral tremor?
166. Where do these findings localize the lesion: 3rd nerve palsy and contralateral ataxia with tremor?
167. Where do these findings localize the lesion: 3rd nerve palsy with vertical gaze palsy, lid retraction, skew deviation, and convergence nystagmus?
168. Where do these findings localize the lesion: 3rd nerve palsy with depressed mental status?

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Questions with answers:
161. Where do these findings localize the lesion: 3rd nerve palsy with contralateral ptosis and contralateral superior rectus weakness?
Midbrain – ipsilateral 3rd nerve nucleus

162. Where do these findings localize the lesion: 3rd nerve palsy with contralateral hemiparesis?
Weber syndrome: Ventral midbrain – ipsilateral 3rd nerve fascicle and cerebral peduncle. It is caused by midbrain infarction as a result of occlusion of the paramedian branches of the posterior cerebral artery or of basilar bifurcation perforating arteries.

163. Where do these findings localize the lesion: 3rd nerve palsy and ipsilateral cerebellar ataxia?
Nothnagel syndrome: Midbrain – ipsilateral 3rd nerve fascicle and cerebral peduncle

164. Where do these findings localize the lesion: 3rd nerve palsy and contralateral tremor?
Benedikt syndrome: Midbrain – ipsilateral 3rd nerve fascicle and red nucleus

165. Where do these findings localize the lesion: 3rd nerve palsy and contralateral ataxia with tremor?
Claude syndrome: Midbrain – ipsilateral 3rd nerve fascicle, red nucleus, and cerebellar peduncle

166. Where do these findings localize the lesion: 3rd nerve palsy with vertical gaze palsy, lid retraction, skew deviation, and convergence nystagmus?
Dorsal midbrain – top of the basilar syndrome

167. Where do these findings localize the lesion: 3rd nerve palsy with depressed mental status?
Transtentorial uncal herniation

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The information below is from Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme

13.7 NOI13 Diplopia 11 – Vertical Eye Movements
Associated neurologic symptoms and signs localize the diplopia to the brainstem. Specific syndromes need to be known because of their highly localizing value (▶Table 13.6).

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13.8 Treatment of Diplopia
Binocular diplopia resolves when the patient closes one eye. Most patients realize this spontaneously and patch one eye to suppress diplopia. This is an acceptable temporary treatment, either until the diplopia resolves by itself or until other treatments are decided on.
Many simple, common sense measures can improve the vision of diplopic patients.
For example, if a patient complains of diplopia only when looking down, then avoiding looking down may be the best treatment. This can be accomplished by recommending correction of presbyopia with single-vision reading glasses instead of bifocal or progressive lenses (which require that the patient look down to read); patients can also be advised to read sitting up with the book on a table or on a book (or music) stand instead of reading lying down in bed.

13.8.1 Patching
Any patch works. A nonsticky, removable patch is more comfortable. Many patients prefer semiopaque tape placed over one lens (on their regular glasses or on sunglasses). It suppresses diplopia as well as an opaque patch but still allows them to see shadows and use their peripheral vision while ambulating (▶Fig. 13.140). 

In adults, patching one eye, even for a long period of time, does not alter visual function. Alternating the patch is not necessary, and patients can choose which eye to patch (they usually prefer not to patch the dominant eye or the eye that sees or moves best).
In young children (<10 years old), prolonged patching may induce amblyopia. This is why it is usually recommended to alternate patching in children.
Patching is usually the best acute solution for sick patients, patients in the hospital or in rehabilitation, and older patients who are at risk of falling.

13.8.2 Prisms
Diplopia can be corrected by placing a prism of appropriate power in front of one eye (the power of the prism is equivalent to the amount of ocular deviation measured with prisms).
This is usually a very good way to correct diplopia as long as the ocular deviation is not too large (usually<20 or 30 prism diopters) and is relatively stable (prisms are not a good solution for myasthenic patients whose diplopia fluctuates during the day).
Prisms are either temporary (Fresnel prisms are thin, soft plastic sheets than can be taped to the patient’s glasses and are easily removed) or permanent (prisms are ground invisibly into permanent glasses). Permanent prisms can be expensive and should be prescribed only when the diplopia has been stable for several months.
Prisms are not perfect because they correct incomitant diplopia in only one direction of gaze and because they degrade visual acuity and can induce distortion. They may not be tolerated in older patients with difficulty walking and with balance disorders.

13.8.3 Strabismus Surgery
Surgery on one or more extraocular muscles is a very effective way to definitively correct ocular misalignment. Surgery is performed only for relatively large deviations once they have been documented to be stable (it is usually recommended to wait at least 6 months after an injury resulting in diplopia before performing strabismus surgery). Surgery is highly successful for simple ocular deviations such as from a sixth nerve palsy or superior oblique paresis. It can be more difficult after a third nerve palsy.

13.8.4 Botulinum Toxin Injection
Injection of botulinum toxin into an extraocular muscle results in temporary (several weeks) paralysis of the muscle. This technique is used to temporarily straighten an eye in rare cases of severe ocular deviation from paralysis of a rectus muscle (e.g., some patients with trauma and a sixth nerve palsy may have a severe deviation of the affected eye toward the nose; injection of botulinum toxin in the medial rectus will weaken the medial rectus, and the eye will straighten for several weeks while recovering its normal function).

Reference: 1. Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme

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