Acute hydrocephalus is a common cause of the Parinaud dorsal midbrain syndrome.^1,2 Most patients with this condition improve either immediately following treatment of the hydrocephalus or within a few months,¹ and it is generally assumed that those who do not do so have no potential for subsequent improvement. I recently evaluated a patient whose upward gaze spontaneously improved 4½ years after treatment of trauma related hydrocephalus.

Case report

A 23 year old Asian man was in his usual excellent general and ocular health until October 2000, when he was struck by a car while walking across the street. He was taken to a local hospital where he was found to have extensive injuries, including bilateral subdural and epidural haematomas. He also had evidence of increased intracranial pressure and required an emergency cranial decompression. Postoperatively, he was evaluated by a neuro-ophthalmologist who noted that the patient’s only ocular disturbance was a mild left trochlear nerve paresis. The paresis resolved within about 3 weeks.

About 6 months after the injury, the patient developed severe headaches and double vision. He was evaluated by the same neuro-ophthalmologist who had evaluated him previously. He noted that the patient now had a severe dorsal midbrain syndrome characterised by lack of elevation of either eye above the midline associated with an exotropia of 25–30 prism dioptres at distance and near, and a left hypotropia of 5 prism dioptres. An evaluation that included neuroimaging and measurement of intracranial pressure revealed hydrocephalus, and the patient underwent placement of a ventriculoperitoneal shunt with normalisation of intracranial pressure, resolution of neuroimaging evidence of hydrocephalus, and resolution of headaches but without any change in ocular motility or alignment. He was eventually referred to the neuro-ophthalmology unit of the Wilmer Eye Institute at the Johns Hopkins Hospital for evaluation and management.

The patient was examined by me for the first time in September 2001, 11 months after the original injury and about 5 months after he had first been noted to have a dorsal midbrain syndrome. At that time, the examination revealed visual acuity of 20/20 in both eyes at distance and near. Automated perimetry revealed bilateral, incomplete, congruous, superior homonymous quadrantic field defects. Pupils were normally reactive to both light and near stimulation. In primary position, the patient had a 25 prism dioptre exotropia that increased to 35 prism dioptres on attempted right gaze and decreased to 15 prism dioptres on attempted left gaze. There was also a 5 prism dioptre left hypotropia. Both eyes could elevate just barely to the midline. There was no difference in degree of elevation with pursuit versus saccades, and elevation did not improve with the oculocephalic manoeuvre. Lateral gaze and downgaze were normal bilaterally for both pursuit and saccadic eye movements. I recommended consideration of strabismus surgery and asked the patient to return in 4 months for reassessment. He did so in January 2002, at which time his ocular motility and alignment were stable. Specifically, neither eye was able to elevate above the midline, either voluntarily or by the oculocephalic manoeuvre.

In May 2002, I performed a left lateral rectus muscle recession of 7.5 mm and a left medial rectus resection of 6.5 mm with superior transposition of both the lateral and medial rectus muscles one muscle width. Postoperatively, the patient had excellent horizontal alignment, although he still had a small left hypotropia of about 5 prism dioptres and was still unable to elevate either eye above the midline.

I subsequently followed the patient at regular intervals. When I examined him in April 2004, he had no change in his ocular motility or alignment, and I recommended that he consider obtaining a small vertical prism to try to eliminate his residual vertical diplopia. I also recommended that he return in 1 year for reassessment. He did so in August 2005.

When I examined the patient in August 2005, he indicated that he thought his vision had improved. He stated that although he was aware of some double vision, it was somewhat less than it had been previously. He also thought his eyes were “moving better.”

On examination, the patient’s visual acuity with correction was 20/15 in each eye at distance and J1 in each eye at near. Colour vision testing using Hardy-Rand-Rittler pseudoisochromatic plates was 10/10 bilaterally. Visual fields were performed by static technique and showed stable bilateral, incomplete, congruous, superior homonymous quadrantic defects, consistent with damage to both inferior occipital lobes. Pupils were isocoric and normally reactive to light and near stimulation. The patient had full abduction, adduction, and infraduction of both eyes. In addition, he now was able to elevate both eyes about 35° above the midline. He had normal velocity saccades in all directions, but he developed convergence-retraction nystagmus when looking at an optokinetic drum whose targets were being rotated downward. When the targets were moving upward, to the right, or to the left, the response was normal. In primary position, the patient had a 4 prism dioptre intermittent left hypotropia at distance and near, associated with 4° of intorsion of the left eye using double Maddox rods. He was most comfortable with a 4 prism dioptre prism placed base up over the left spectacle lens, and a Fresnel prism of this strength and orientation was placed on the left lens of his glasses. He had no ptosis or lid retraction, and the results of slit lamp biomicroscopy, applanation tonometry, and ophthalmoscopy were normal.

Comment

The dorsal midbrain syndrome of Parinaud usually results from damage to premotor pathways for binocular upward gaze in the dorsal mesencephalon.² Depending on the extent of damage, the patient may have pursuit saccadic dissociation, with better upward gaze during pursuit than when attempting upward saccades, and some patients have improved upward gaze with the oculocephalic manoeuvre, indicating sparing of infranuclear pathways. The dorsal midbrain syndrome may be caused by extrinsic or intrinsic lesions, with hydrocephalus being a common aetiology in some series.^1,3 Depending on the nature and extent of damage as well as the length of time the condition has been present before the underlying disorder is treated, some patients improve, often substantially, whereas others do not. In general, patients whose underlying condition is treated successfully but who do not improve within a few weeks to months are thought to have no potential to improve; however, our patient’s spontaneous improvement about 4½ years after onset and treatment of the underlying condition indicates that some patients retain the potential to improve even after several years have passed. This information may be of value in counselling patients with the dorsal midbrain syndrome who ask if there is any chance of improvement when none has occurred after months to a few years.