science

Parinaud's syndrome

Parinaud's syndrome is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Parinaud's syndrome rather than just read about it. In short: Parinaud's syndrome is a constellation of neurological signs indicating injury to the dorsal midbrain. More specifically, compression of the vertical gaze center at the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF).

Key takeaways

Parinaud's syndrome belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Parinaud's syndrome to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Parinaud's syndrome from memory before moving on to harder problems.

Reference excerpt

Parinaud's syndrome is a constellation of neurological signs indicating injury to the dorsal midbrain. More specifically, compression of the vertical gaze center at the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF). It is a group of abnormalities of eye movement and pupil dysfunction and is named for Henri Parinaud (1844–1905), considered to be the father of French ophthalmology.

Signs and symptoms Parinaud's syndrome is a cluster of abnormalities of eye movement and pupil dysfunction, characterized by:

Paralysis of upwards gaze: Downward gaze is usually preserved. This vertical palsy is supranuclear, so doll's head maneuver should elevate the eyes, but eventually all upward gaze mechanisms fail. In the extreme form, conjugate down gaze in the primary position, or the "setting-sun sign" is observed. Neurosurgeons see this sign most commonly in patients with hydrocephalus. Pseudo-Argyll Robertson pupils: Accommodative paresis ensues, and pupils become mid-dilated and show light-near dissociation. Convergence-retraction nystagmus: Attempts at upward gaze often produce this phenomenon. On fast up-gaze, the eyes pull in and the globes retract. The easiest way to bring out this reaction is to ask the patient to follow down-going stripes on an optokinetic drum. Eyelid retraction (Collier's sign) It is also commonly associated with bilateral papilledema. It has less commonly been associated with spasm of accommodation on attempted upward gaze, pseudoabducens palsy (also known as thalamic esotropia) or slower movements of the abducting eye than the adducting eye during horizontal saccades, see-saw nystagmus and associated ocular motility deficits including skew deviation, oculomotor nerve palsy, trochlear nerve palsy and internuclear ophthalmoplegia.

Causes

Parinaud's syndrome results from injury, either direct or compressive, to the dorsal midbrain. Specifically, compression or ischemic damage of the mesencephalic tectum, including the superior colliculus adjacent oculomotor (origin of cranial nerve III) and Edinger-Westphal nuclei, causing dysfunction to the motor function of the eye. Classically, it has been associated with three major groups:

Young patients with brain tumors in the pineal gland or midbrain, causing hydrocephalus Women in their 20s-30s with multiple sclerosis Older patients following stroke of the upper brainstem However, any other compression, ischemia or damage to this region can produce these phenomena: hydrocephalus, midbrain hemorrhage, cerebral arteriovenous malformation, trauma and brainstem toxoplasmosis infection. Neoplasms and giant aneurysms of the posterior fossa have also been associated with the midbrain syndrome. Vertical supranuclear ophthalmoplegia has also been associated with metabolic disorders, such as Niemann-Pick disease, Wilson's disease, kernicterus, and barbiturate overdose.

Diagnosis Diagnosis can be made via combination of physical exam, particularly deficits of the relevant cranial nerves. Confirmation can be made via imaging, such as CT scan or MRI.

Treatment Treatment is primarily directed towards etiology of the dorsal midbrain syndrome. A thorough workup, including neuroimaging is essential to rule out anatomic lesions or other causes of this syndrome. Visually significant upgaze palsy can be relieved with bilateral inferior rectus recessions. Retraction nystagmus and convergence movement are usually improved with this procedure as well.

Prognosis The eye findings of Parinaud's syndrome generally improve slowly over months, especially with resolution of the causative factor; continued resolution after the first 3–6 months of onset is uncommon. However, rapid resolution after normalization of intracranial pressure following placement of a ventriculoperitoneal shunt has been reported.

References

Further reading Aguilar-Rebolledo F, Zárate-Moysén A, Quintana-Roldán G (1998). "Parinaud's syndrome in children". Rev. Invest. Clin. (in Spanish). 50 (3): 217–20. PMID 9763886. Waga S, Okada M, Yamamoto Y (1979). "Reversibility of Parinaud syndrome in thalamic hemorrhage". Neurology. 29 (3): 407–9. doi:10.1212/wnl.29.3.407. PMID 571990. S2CID 42247406.

External links

Illustrations

Worked examples

Example 1 — a first encounter with Parinaud's syndrome

Start with the simplest possible case. Write down what Parinaud's syndrome claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Parinaud's syndrome before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Parinaud's syndrome ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Parinaud's syndrome

In research: Parinaud's syndrome appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Parinaud's syndrome in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Parinaud's syndrome is common in secondary-school and first-year university syllabi. It links to neighbouring topics Disorders of ocular muscles, binocular movement, accommodation and refraction, Medical signs, Syndromes affecting the nervous system, so understanding it makes those chapters shorter.
In everyday life: Look for Parinaud's syndrome outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Parinaud's syndrome in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Parinaud's syndrome means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Parinaud's syndrome out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Parinaud's syndrome in simple terms?

Why does Parinaud's syndrome matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Parinaud's syndrome?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Parinaud's syndrome.