Gaze Preference, Gaze Palsy, and Tonic Deviations
Gaze preference is an acute inability to produce gaze contralateral to the side of a cerebral (supranuclear) lesion; it is accompanied by a tendency for tonic deviation of the eyes toward the side of the lesion. In such cases, the doll’s head maneuver generates a full range of horizontal eye movements because the vestibular-ocular pathways are intact. Stroke is the most common etiology for this type of cerebral injury. The eye movement dysfunction is generally temporary, lasting only days or weeks. Presumably, alternative cerebral-bulbar pathways (perhaps from the parietal lobe) become increasingly capable of generating the saccades and maintaining central gaze.
Gaze palsy is a symmetric limitation of the movements of both eyes in the same direction (ie, a conjugate ophthalmoplegia). Brainstem lesions that produce a horizontal gaze palsy disrupt eye movements toward the side of the lesion (opposite to the pattern observed with lesions of the FEF). With CN VI nuclear lesions, a gaze palsy occurs because the CN VI nucleus also contains internuclear neurons destined for the contralateral CN III subnucleus via the MLF. CN VI nuclear lesions damage the final common site for supranuclear innervation of horizontal eye movements; thus, the doll’s head maneuver is ineffective in driving the paretic eyes toward the side of the lesion. Bilateral pontine injury can abolish all horizontal eye movements (Fig 8-4). This devastating injury still allows vertical eye movements, which often occur spontaneously (ie, ocular bobbing). Congenital horizontal gaze palsy can occur as part of Möbius syndrome, in which aplasia of the CN VI nuclei is accompanied by bilateral facial paresis.
Vertical gaze palsies can manifest as selective limitation of upgaze or downgaze. In either case, the lesion is usually in the midbrain. Limitation of conjugate upgaze occurs with damage to the pretectum, an isthmus between the superior colliculi and the thalamus. Supranuclear fibers that control vertical gaze (upgaze greater than downgaze) decussate through the pretectum (posterior commissure) as they pass to the riMLF, the midbrain structure that functions as the saccadic generator for vertical eye movements (and thus is the homologue of the PPRF for horizontal saccades). Clinical manifestations of dorsal midbrain syndrome (also known as pretectal or Parinaud syndrome) (Fig 8-5) include
Figure 8-4 Axial magnetic resonance imaging (MRI) scan of a brain. T1-weighted image without contrast shows signal hyperintensity (arrows) in the bilateral pons. This 67-year-old patient reported “trouble moving my eyes” and was found to have a virtually complete horizontal gaze palsy, consistent with ischemia involving the paramedian pontine reticular formation on both sides. She had no other focal neurologic deficits.
(Courtesy of Prem S.Subramanian, MD, PhD.)
conjugate limitation of vertical gaze (usually upgaze)
co-contraction of extraocular muscles with attempted upgaze (convergence-retraction nystagmus)
mid-dilated pupils with light–near dissociation
retraction of the eyelids in primary position (Collier sign)
disruption of convergence (convergence spasm or convergence palsy)
Patients with dorsal midbrain syndrome often present with only a subset of these signs, although the limitation of conjugate upgaze is the most common feature. Common etiologies of this syndrome include hydrocephalus, ventriculoperitoneal shunt malfunction, mass lesions (especially pineal-based tumors), multiple sclerosis, stroke, and Whipple disease. Workup must include neuroimaging. Treatment consists of addressing the underlying etiology. Residual diplopia can be treated with prisms, and upgaze deficits can be improved with strabismus surgery.
The pretectum is the terminal structure supplied by the artery of Percheron (small penetrating arteries that arise from the area around the top of the basilar artery; see Chapter 1). Stenosis at the origin of these vessels, disease of the more proximal basilar artery, or entrapment of emboli that lodge at the top of the basilar artery can infarct the riMLF, resulting in vertical saccadic gaze deficits with relative sparing of vertical pursuit and vestibular-ocular movements.
Figure 8-5 Dorsal midbrain syndrome. A, A patient with a germinoma pressing on the pretectum shows a poor pupillary light reaction. B, The near reaction of the pupils is good. C, Attempted upgaze is poorly done. D, MRI (T1-weighted with contrast) shows pineal (white arrow) and chiasmal (yellow arrow) germinoma with involvement of the dorsal midbrain, located beneath the pineal lesion.
(Parts A–C used with permission from Albert DM, Jakobiec FA, eds. Principles and Practice of Ophthalmology, vol 2. Philadelphia: Saunders; 1994:2476. Part D courtesy of Prem S. Subramanian, MD, PhD.)
Deviation of the eyes may occur with seizures involving any cerebral lobe. Most notably, a lesion of the FEF that causes excess neural activity, such as a focal seizure, will drive the eyes contralaterally during the period of the seizure. The head also may turn contralateral to the seizure focus during the ictus. In the postictal state, when there may be lingering hypoactivity of the FEF neurons, the eyes may deviate ipsilateral to the side of the lesion because of a relative increase in input from the unaffected FEF on the opposite side of the brain.
Transient and conjugate downward or upward ocular deviation may occur in healthy newborns. In these cases, the vertical doll’s head maneuver can move the eyes out of their tonically held position. Tonic downgaze in premature newborns, however, may be associated with serious neurologic disease, especially when intraventricular hemorrhage expands the third ventricle and presses on the pretectum. Tonic downward deviation of the eyes combined with retraction of the eyelids, referred to as the setting sun sign, is primarily observed in children as part of dorsal midbrain syndrome. Conjugate paresis of upgaze is an associated finding, and in these cases, the doll’s head maneuver cannot induce upward movements of the eyes.
Oculogyric crisis is a tonic upward ocular deviation, sometimes directed toward the right or left. Patients find it difficult to direct their eyes downward. This disorder often arises from an idiosyncratic reaction to neuroleptic antipsychotic drugs such as haloperidol and fluphenazine, as well as antiemetic drugs such as metoclopramide, which are strong dopaminergic blockers. These drugs alter supranuclear input onto the ocular motor nuclei. The crisis may persist for hours. Patients with Wilson disease may have an oculogyric crisis. Administration of anticholinergic drugs (eg, prochlorperazine) promptly stops the crisis.
Buckley EG, Holgado S. Surgical treatment of upgaze palsy in Parinaud’s syndrome. J AAPOS. 2004;8(3):249–253.
Caplan LR. “Top of the basilar” syndrome. Neurology. 1980;30(1):72–79.
Corbett JJ. Neuro-ophthalmic complications of hydrocephalus and shunting procedures. Semin Neurol. 1986;6:111–123.
Keane JR. The pretectal syndrome: 206 patients. Neurology. 1990;40(4):684–690.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.