Parinaud Syndrome

Question 1

PARINAUD’S causes

Answer 1

This is relatively rare and is caused by lesions in the upper midbrain (DORSAL MIDBRAIN SYNDROME)
Pineal Tumours are more common in adolescent males (pinealoma)
Metastases and gliomas
Hydrocephalous - dilatation of IIIrd ventricles results in compression of posterior commissure
Atherosclerosis
Accident/Trauma
Embolism, Vasculitis

Question 2

PARINAUD’S features

Answer 2

• A gaze disorder. The initial sign is a loss of upward saccadic movement in the presence of normal vertical smooth pursuit.
  gaze-evoked downbeat- nystagmus

Tonic downward deviation of eyes (sun-setting sign)

In progressive lesions may be followed by loss of down gaze and eventually complete vertical gaze paralysis affecting smooth pursuit, VOR movements and a loss in Bell’s phenomenon).

If the stripes of an OKN (optokinetic nystagmus) drum are slowly rotated downwards, the absence of a refixating upward movement can be clearly seen. Upward rotation of the drum results in a normal optokinetic nystagmus response due to the preservation of upward pursuit movement. OKN will be normal when rotated upwards.

Convergence retraction ‘nystagmus’. A characteristic feature of Parinaud’s syndrome is rhythmical convergence of the visual axes and associated retraction of the globes on attempted up-gaze. This is also best demonstrated by testing optokinetic nystagmus, rotating the stripes downwards. The lesion is thought to cause disinhibition of the ocular motor nuclei allowing bursts of co-firing of the extra-ocular muscles.

As the MR is the most powerful muscle this results in convergence and a retraction of the globe
* Pathological upper eyelid retraction (Collier’s sign). Upper eyelid retraction is usually associated with lid-lag and is best seen on down-gaze. One or both eyes can be affected.
* Pupil abnormalities. The pupils are usually dilated and show a reduction in response to direct and consensual light stimulation. However, pupil constriction is normal on accommodation. This disparity in pupil reaction is known as light/near dissociation.
* Papilledema. When the cause of Parinaud’s syndrome is a space-occupying lesion, usually a pinealoma, there is eventually a rise in intracranial pressure followed by papilloedema. However, this is a late sign.
Accommodation insufficiency, blurred vision and VF defects due to optic nerve vf defects

Question 3

PARINAUD’S mx

Answer 3

In dorsal midbrain syndrome, a head-up posture may be adopted to move eyes away from restricted upgaze or to avoid diplopia/convergence retraction nystagmus.
Base-up deviating prisms can help with the head-up position, though rarely tolerated by ambulatory patients.
Recession of both inferior rectus muscles can improve up-gaze range and help correct head posture.
The use of adjustable sutures can reduce the risk of inducing a vertical deviation