Internuclear ophthalmoplegia, prenuclear paresis of contralateral superior rectus, and bilateral ptosis

Mesencephalic and associated posterior circulation infarcts

BACKGROUND AND PURPOSE

The purposes of this study were to evaluate and review the risk factors and clinical features of patients with posterior circulation stroke involving mesencephalon and neighboring structures and to describe the clinical syndromes according to the mesencephalic arterial territory involved.

METHODS

We studied all patients with acute posterior circulation stroke involving mesencephalon who were admitted consecutively to our stroke unit over a 6-year period. We selected these patients (3%) from 1296 patients with posterior circulation infarct. Neurological and radiological investigations, including MRI and angiography, were performed in all cases. We classified patients into 4 groups on the basis of MRI findings: (1) isolated mesencephalic infarcts (9 patients); (2) distal territory infarcts (19 patients), including mesencephalon, thalamus, medial temporal and occipital lobes, and cerebellum; (3) middle territory infarcts (12 patients), including the pons and anterior inferior cerebellar artery territory; and (4) proximal territory infarcts (1 patient), including the medulla and posterior inferior cerebellar artery territory.

RESULTS

Middle mesencephalon involvement was the most common in all groups, and the anteromedial territory was frequently affected, depending on the direct perforators of basilar artery. In patients with isolated mesencephalic infarct, the clinical picture was dominated by nuclear or fascicular third-nerve palsy and contralateral motor deficits. The distal territory involvement was the most common and associated with consciousness disturbances, gait ataxia, ocular motor disturbances, and visual field deficits. The neurological picture of middle territory infarcts was dominated by consciousness disturbances with dysarthria, horizontal ocular motor disorders, and hemiparesis. Proximal territory involvement was rare and associated with acute unsteadiness, vertigo, dysphagia, dysphonia, tetra-ataxia, and motor weakness. The most common cause of stroke was large-artery disease in 16 patients (39%), cardioembolism in 8 (20%), and small-artery disease with lacunar mesencephalic infarct in 10 (24%). Bilateral mesencephalic infarcts were not uncommon (27%), mainly in patients with multiple and extended infarcts in the posterior circulation, and were associated with poor outcome compared with unilateral infarct.

CONCLUSIONS

Our study highlights the topographic and clinical heterogeneity of the acute posterior circulation infarcts involving mesencephalon. The variety of the underlying potential causes of stroke requires detailed investigations of the extra and intracranial arteries and the heart.

Vertical gaze palsy induced by midbrain lesions and its structural imaging

We experienced four cases of vertical gaze palsy induced by midbrain lesions. Lesions commonly covered the rostral midbrain, including the rostral interstitial nucleus, dorsomedial to the red nucleus. Two of the four cases resulted from vascular insult, in which a single, unpaired perforator is supposed to innervate the rostral midbrain and medial thalamus bilaterally. One case showed vertical gaze palsy accompanied by bilateral ptosis. The findings agree with recent experimental evidence that a neural substrate in eyelid control lies in the supraoculomotor area immediately dorsal to the oculomotor nucleus. The remaining two cases, a brain hemorrhage and an inflammatory tumor, showed unilateral lesions of the rostral midbrain. In these cases, vertical gazes were not abolished, but were limited in an incomplete way. This may be explained by partial damages of the descending fibers, some of which decussate through the posterior commissure before it reaches the oculomotor nucleus. Thus, clinical signs and symptoms were clarified based on anatomical and physiological points of view.

Bilateral ophthalmoplegia: an unusual sign of the top of the basilar artery syndrome

Bilateral ophthalmoplegia may be an unusual sign of vertebrobasilar ischemia. We report the cases of two patients (75 and 73 years old), who suddenly developed drowsiness, bilateral ophthalmoplegia with bilateral ptosis and mild right hemiparesis. In both patients, MRI revealed bilateral thalamic and midbrain infarcts, ECG showed the presence of atrial fibrillation and Doppler study of the extracranial and intracranial vertebral arteries found no significant alterations. Ischemia involving the midbrain and thalamic paramedian regions may cause bilateral ophthalmoplegia and consciousness disturbances. In these two cases, the most plausible etiologic mechanism was cardiac embolism, and the prognosis for bilateral ocular palsy was poor.

Monocular elevation paresis and contralateral downgaze paresis from unilateral mesodiencephalic infarction

A 26 year old woman presented with monocular elevation paresis of the right eye, contralateral paresis of downward gaze, and subtle bilateral ptosis. Magnetic resonance imaging disclosed a unilateral embolic infarction restricted to the mesodiencephalic junction involving the left paramedian thalamus. Preserved vertical oculocephalic movements and intact Bell's phenomenon suggested a supranuclear lesion. This rare "crossed vertical gaze paresis" results from a lesion near the oculomotor nucleus affecting ipsilateral downward gaze and contralateral upward gaze fibres, originating in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF).

Bilateral central ptosis in acquired immunodeficiency syndrome

A man with acquired immune deficiency syndrome suddenly developed bilateral complete ptosis and minor vertical gaze limitation. Magnetic resonance imaging revealed a lesion in the midbrain surrounding the sylvian aqueduct in addition to bilateral masses in the caudate nuclei. Pathologic examination showed that the caudate lesions were central nervous system lymphoma of B cell origin, but the midbrain lesion contained only signs of AIDS encephalopathy. The periaqueductal lesion involved the caudal central subnucleus and probably also the subnuclei of the superior and inferior recti of the oculomotor nuclear complex bilaterally.

Ophthalmoplegia with bilateral ptosis secondary to midbrain hemorrhage. A case with clinical and radiologic correlation

A 65-year-old white female presented with the sudden onset of headaches, bilateral ptosis, and complete ophthalmoplegia. Other than a mild decrease in mental status, she was neurologically intact. Magnetic resonance imaging (MRI) and computed tomography (CT) examinations showed a midline hemorrhage extending from the caudal diencephalon to the pontomesencephalic junction affecting the oculomotor complex, the medial longitudinal fasciculus (MLF), and the rostral parapontine reticular formation (PPRF). Ischemic changes were also noted in the midline pontine tegmentum possibly affecting root fibers from the abducens nuclei. Angiography was negative for a vascular anomaly. The radiologic findings are correlated with current models of oculomotor organization to provide an explanation for this patient's unique clinical presentation.

Isolated or predominant ocular motor nerve palsy as a manifestation of brain stem stroke

BACKGROUND AND PURPOSE

There have been few reports of strokes producing isolated or predominant ocular motor nerve palsies as a clinical manifestation.

METHODS

We studied seven patients with brain stem stroke who had ocular motor palsies as the only or the predominant neurological manifestation, and we correlated their clinical features with radiological findings.

RESULTS

Five patients had small strokes in the area of oculomotor nuclei or fascicles and showed various combinations of oculomotor disturbances. Three of these patients showed vertical gaze paresis of the opposite eye. One patient with a small hemorrhage near the aqueduct of Sylvius showed fourth nerve palsy on the contralateral side, and a patient with a small infarct in the pontine tegmentum showed isolated sixth nerve palsy. Nonocular minor neurological signs included trigeminal sensory changes in four patients and clumsy arm in two. Ocular and nonocular dysfunctions generally improved within several months. Radiological findings of the brain stem correlated well with the ocular signs.

CONCLUSIONS

We conclude that acute brain stem stroke should be included in the differential diagnosis of isolated ocular motor nerve palsies and that appropriate diagnostic investigations should be performed in these cases.

Paramedian thalamopeduncular infarction: clinical syndromes and magnetic resonance imaging

We prospectively examined 11 patients with magnetic resonance imaging-documented infarction in the paramedian thalamopeduncular region, which is supplied by the superior mesencephalic and posterior thalamosubthalamic arteries. Variations in the size and rostral-caudal extent of infarction correlated with the following three clinical patterns: (1) With unilateral paramedian mesencephalic infarction, an ipsilateral third nerve paresis was accompanied by mild contralateral hemiparesis or hemiataxia. Contralateral ptosis and impaired upgaze were observed in two patients; one of them showed additional damage to the posterior commissure. (2) With bilateral infarction in the thalamopeduncular junction, involving the mesencephalic reticular formation, supranuclear vertical gaze defects were accompanied by impaired consciousness or memory, and mild aphasia in some patients. Persistent amnesia was observed only when the dominant anterior nucleus or mamillothalamic tract was damaged. (3) With larger thalamopeduncular infarcts, partial or complete third nerve paresis was combined with supranuclear gaze disturbance and delayed contralateral tremor. An unusual gaze disorder, a variant of the vertical "one-and-a-half syndrome," occurred with a small strategically placed lesion at the thalamopeduncular junction, best explained by selective damage to supranuclear pathways or partial nuclear involvement. The primary cause of these infarctions was embolism to the basilar apex or local atheroma at the origin of the posterior cerebral artery.

Monocular downbeat nystagmus

A patient with sporadic pontocerebellar degeneration and downbeat nystagmus limited to the left eye is described. The nystagmus was not modified by head movements, but was associated with a purely tonic upgaze paresis in the same eye. Absence of internuclear ophthalmoplegia indicated sparing of the medial longitudinal fasciculus. It is suggested that the vertical oculomotor abnormalities are due to dysfunction of the ipsilateral brachium conjunctivum.

Upgaze palsy and monocular paresis of downward gaze from ipsilateral thalamo-mesencephalic infarction: a vertical "one-and-a-half" syndrome

A patient with an infarct limited to the paramedian thalamus and upper mesencephalon on the right side suffered a conjugate upgaze palsy associated with a monocular paresis of downward gaze in the ipsilateral eye (vertical "one-and-a-half" syndrome). This paresis involved tonic and phasic components. Vertical oculocephalic movements and conjugate horizontal gaze were normal. It is suggested that the unilateral lesion destroyed the fibres of the posterior commissure and the descending fibres to the ipsilateral subnucleus of the inferior rectus and contralateral subnucleus of the superior oblique just after they decussate, probably above the level of the third nerve nucleus. A complex disturbance of vertical gaze may be due to a unilateral thalamo-mesencephalic lesion.