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

Vertical one-and-a-half syndrome in a patient with pecheron artery ischemia: A case report

Vertical one-and-a-half syndrome (VOHS) is an uncommon presentation resulting from a unilateral thalamomesencephalic stroke with involvement of the rostral interstitial nucleus of the medial longitudinal fasciculus and posterior commissure. The artery of Percheron (aPe) is a branch of the posterior cerebral artery (PCA) and it is a variant that arises as a solitary trunk supplying both medial thalami and upper midbrain. A 78-year-old female patient, presented at the hospital emergency with approximately 12 hours of sudden onset of diplopia, associated with dizziness. Neurological exam revealed torsional nystagmus associated with bilateral upgaze palsy with limitation of infraduction on the left. We describe a rare case of VOHS associated with ischemic alterations at the MRI suggesting an aPe impairment. The conjugate gaze control lies anatomically at the midbrain at the central nervous system (CNS). This report describes a rare type of VOHS and brings a new insight on a possible aPe topography possibly causing this clinical presentation.

Intermittent Vertical Diplopia as a Rare Manifestation of a Rare Cerebral Infarct: Artery of Percheron Ischemic Infarct and Sidelights on the Phenotypic Variability of Thalamic Ocular Disorders

The thalamus is a complex structure with over 40 named nuclei. Ischemic lesions of the thalamus exhibit a panorama of phenomena ranging from facial numbness to ocular and visual field disturbances to hemiplegia, behavioral disorders, and stupor. It is a dense neuronal hub with a bewildering variety of connections and functions. We present an intriguing case of intermittent vertical diplopia due to an artery of Percheron ischemic infarct of the bilateral paramedian thalami. We seize upon this opportunity to simplify the thalamic nuclei sub-divisions and their vascular supply. In this process, we outline the phenotypic variability of thalamic diplopia and ophthalmoplegia and their various underlying mechanisms.

Bilateral, vertical supranuclear gaze palsy following unilateral midbrain infarct

A 60-year-old man recently admitted for bipedal oedema, endocarditis and a persistently positive COVID-19 swab with a history of anticoagulation on rivaroxaban for atrial fibrillation, transitional cell carcinoma, cerebral amyloid angiopathy, diabetes and hypertension presented with sudden onset diplopia and vertical gaze palsy. Vestibulo-ocular reflex was preserved. Simultaneously, he developed a scotoma and sudden visual loss, and was found to have a right branch retinal artery occlusion. MRI head demonstrated a unilateral midbrain infarct. This case demonstrates a rare unilateral cause of bilateral supranuclear palsy which spares the posterior commisure. The case also raises a question about the contribution of COVID-19 to the procoagulant status of the patient which already includes atrial fibrillation and endocarditis, and presents a complex treatment dilemma regarding anticoagulation.

Ocular Motor Dysfunction Due to Brainstem Disorders

BACKGROUND

The brainstem contains numerous structures including afferent and efferent fibers that are involved in generation and control of eye movements.

EVIDENCE ACQUISITION

These structures give rise to distinct patterns of abnormal eye movements when damaged. Defining these ocular motor abnormalities allows a topographic diagnosis of a lesion within the brainstem.

RESULTS

Although diverse patterns of impaired eye movements may be observed in lesions of the brainstem, medullary lesions primarily cause various patterns of nystagmus and impaired vestibular eye movements without obvious ophthalmoplegia. By contrast, pontine ophthalmoplegia is characterized by abnormal eye movements in the horizontal plane, while midbrain lesions typically show vertical ophthalmoplegia in addition to pupillary and eyelid abnormalities.

CONCLUSIONS

Recognition of the patterns and characteristics of abnormal eye movements observed in brainstem lesions is important in understanding the roles of each neural structure and circuit in ocular motor control as well as in localizing the offending lesion.

Rare valiant vertical one-and-a-half syndrome without ipsilateral upward gaze palsy in a patient with thalamomesencephalic stroke

Bilateral upward and ipsilateral downward gaze palsy due to a unilateral thalamomesencephalic stroke is called vertical one‐and‐a‐half syndrome (VOHS). Here, we report a valiant VOHS case who presented contralateral upward and ipsilateral downward gaze palsy due to a unilateral thalamomesencephalic stroke. The neuronal fiber connections associated with vertical gaze are not completely understood, so the present case provides an important proof to obtain a better understanding of vertical gaze mechanisms.

Unilateral asterixis, thalamic astasia and vertical one and half syndrome in a unilateral posterior thalamo-subthalamic paramedian infarct: An interesting case report

A 42-year-old young lady presented with acute onset of dizziness, drooping of left eye with binocular diplopia and inability to walk unassisted. She had past history of uncontrolled diabetes mellitus and hypertension. On examination, she had left fascicular type of third nerve palsy, vertical one and half syndrome (VOHS), left internuclear ophthalmoplegia and skew deviation with ipsilesional hypertropia. She also had thalamic astasia and right unilateral asterixis. Her MRI revealed T2 and Flair hyper intense signal changes with restricted diffusion in the left thalamus, subthalamus and left midbrain. MR Angiography was normal. Thalamic-subthalamic paramedian territory infarct is relatively uncommon. It can present with oculomotor abnormalities including vertical one and half syndrome, skew deviation, thalamic astasia and asterixis. This case is reported for the rarity of the presenting clinical findings in unilateral thalamo-mesencephalic infarcts.

A hypothetical scheme for the brainstem control of vertical gaze

OBJECTIVES

To develop a hypothetical scheme to account for clinical disorders of vertical gaze based on recent insights gained from experimental studies.

METHODS

The authors critically reviewed reports of anatomy, physiology, and effects of pharmacologic inactivation of midbrain nuclei.

RESULTS

Vertical saccades are generated by burst neurons lying in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). Each burst neuron projects to motoneurons in a manner such that the eyes are tightly coordinated (yoked) during vertical saccades. Saccadic innervation from riMLF is unilateral to depressor muscles but bilateral to elevator muscles, with axons crossing within the oculomotor nucleus. Thus, riMLF lesions cause conjugate saccadic palsies that are usually either complete or selectively downward. Each riMLF contains burst neurons for both up and down saccades, but only for ipsilateral torsional saccades. Therefore, unilateral riMLF lesions can be detected at the bedside if torsional quick phases are absent during ipsidirectional head rotations in roll. The interstitial nucleus of Cajal (INC) is important for holding the eye in eccentric gaze after a vertical saccade and coordinating eye-head movements in roll. Bilateral INC lesions limit the range of vertical gaze. The posterior commissure (PC) is the route by which INC projects to ocular motoneurons. Inactivation of PC causes vertical gaze-evoked nystagmus, but destructive lesions cause a more profound defect of vertical gaze, probably due to involvement of the nucleus of the PC. Vestibular signals originating from each of the vertical labyrinthine canals ascend to the midbrain through several distinct pathways; normal vestibular function is best tested by rotating the patient's head in the planes of these canals.

CONCLUSIONS

Predictions of a current scheme to account for vertical gaze palsy can be tested at the bedside with systematic examination of each functional class of eye movements.

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.

Binocular vertical diplopia

The assessment of a patient with binocular vertical diplopia begins with a thorough history and neuro-ophthalmologic examination. The neuro-ophthalmologic examination includes observation for a compensatory head, face, or chin position; ocular ductions and versions in the nine cardinal positions of gaze; the three-step test; the double Maddox rod test; indirect ophthalmoscopy to observe the location of the fovea in relationship to the optic nerve head to determine cyclodeviation; and the forced ductions test. Binocular vertical diplopia may be due to supranuclear processes, ocular motor nerve dysfunction, neuromuscular junction disease, diseases of eye muscle, mechanical processes causing vertical eye misalignment, and even retinal disease. In this article, the differential diagnosis of these processes is outlined.

Downgaze paresis following severe head trauma in a child

A 4 1/2-year-old girl developed a downgaze paresis following severe head trauma. Magnetic resonance imaging showed evidence of peri-aqueductal lesions in the rostral midbrain in the region of the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). Twenty five weeks following the injury, the downgaze paresis remained unchanged but she developed convergence retraction nystagmus on attempted upgaze. Repeat imaging did not show any change in the lesions in the rostral midbrain. This report provides further evidence for the riMLF in the control of downgaze, and a synkinesis is postulated for the development of the convergence retraction nystagmus.

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).

Spatial organization of premotor neurons related to vertical upward and downward saccadic eye movements in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) in the cat

The rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) contains premotor neurons that are related to the control of vertical and torsional saccadic eye movements. In the present study, complimentary light microscopic anterograde biocytin and retrograde horseradish peroxidase experiments have been performed to determine the organization of premotor neurons in the riMLF in the cat that are related intimately to the vertical motoneuron populations in the oculomotor and trochlear nuclei. The results indicate a rostral-caudal topographic arrangement of neurons in the riMLF that is related to the target projections to vertical downward (inferior rectus and superior oblique) and vertical upward (superior rectus and inferior oblique) motoneurons, respectively, in the oculomotor and trochlear nuclei. Both the anterograde and the retrograde studies are consistent, in that they demonstrate the tendency for downward and upward riMLF neurons to be separated spatially by a distance of approximately 0.5 mm in the rostral-caudal axis of the nucleus. The riMLF projections to inferior oblique and superior oblique motoneurons are predominantly ipsilateral. Projections to inferior rectus and superior rectus motoneurons, however, are bilateral, and, presumably, they provide one means for assuring the conjugacy of vertical saccadic eye movements. Because premotor burst neurons that encode parameters for upward or downward saccades are intermingled within the riMLF, and excitatory and inhibitory premotor neurons also coexist in this region, the findings from this study suggest that subregions of the riMLF contain coexistent populations of excitatory and inhibitory neurons that are related to opposite directions of vertical eye movements. The spatial segregation of excitatory premotor neurons in the riMLF that are related to vertical upward vs. downward movements, furthermore, provides a basis for the interpretation of vertical upward and/or downward gaze palsies that might result from discrete lesions at the mesodiencephalic junction in humans.

Morphology and soma-dendritic distribution of synaptic endings from the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) on motoneurons in the oculomotor and trochlear nuclei in the cat

The morphology and soma-dendritic distribution of anterograde biocytin-labelled rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) synaptic endings in the oculomotor and trochlear nuclei have been examined by electron microscopy by using both preembedding immunoperoxidase and postembedding immunogold methods. The results indicate that three morphological types of riMLF synaptic endings are distinguishable on the basis of synaptic vesicle morphology (spheroidal, pleiomorphic, or ellipsoidal) and postsynaptic membrane specializations (asymmetrical or symmetrical). All three morphological types of riMLF synaptic endings establish synaptic connections predominantly with dendrites. Synaptic endings that contain ellipsoidal synaptic vesicles have a more proximal soma-dendritic distribution than those that contain either spheroidal or pleiomorphic synaptic vesicles. Furthermore, all three morphological types of synaptic endings are encountered in the same motoneuron subdivisions of the oculomotor and trochlear nuclei in the same experiments. The findings suggest that subregions of the riMLF contain coexistent populations of excitatory and inhibitory premotor neurons that are related to opposite directions of vertical saccadic eye movements but that project to the same motoneuron subgroups on the ipsilateral side. Both the morphology and the mode, pattern, and soma-dendritic distribution of saccade-related riMLF synaptic endings that establish synaptic connections with vertical motoneurons differ from those of excitatory and inhibitory second-order vertical vestibular synaptic endings. These differences in the synaptic organization of riMLF and second-order vestibular inputs to oculomotor and trochlear motoneurons may be related to differences in the information transferred by each source, the riMLF input conveying eye-velocity signals, and the vestibular input conveying eye-position signals.

Small primary intracerebral hemorrhage. Clinical presentation of 28 cases

BACKGROUND

Although there have been sporadic reports of patients with small intracerebral hemorrhages presenting with discrete clinical features, the clinical and distributional characteristics of these hemorrhages have not been adequately investigated.

CASE DESCRIPTIONS

We studied 28 patients who had primary intracerebral hemorrhage of a longest diameter < or = 1.5 cm as seen in computed tomographic scan and/or magnetic resonance imaging. Small primary intracerebral hemorrhages were found in the basal ganglia in 8 patients (2 with intraventricular hemorrhage), the posterior limb of the internal capsule in 8, the area of the fourth ventricle of the cerebellum in 7 (5 with intraventricular hemorrhage), the pontine tegmentum in 4, and the thalamomesencephalic area in 1. All patients except 3 were hypertensive, suggesting that most of the hemorrhages may have occurred because of rupture of small end arteries secondary to long-standing hypertension. Depending on their location, the hemorrhages clinically manifested as pure motor stroke in 7, pure sensory stroke in 6, vertigo/ataxia in 7, sensorimotor stroke in 4, and ataxic hemiparesis in 2 patients. One patient with thalamomesencephalic hemorrhage showed vertical gaze disturbance, and 1 with basal ganglionic hemorrhage presented with symptoms of acute hydrocephalus secondary to a relatively large amount of intraventricular hemorrhage. The prognosis of small intracerebral hemorrhage was generally excellent except for when patients were very old or when there was a significant amount of intraventricular bleeding.

CONCLUSIONS

Small primary intracerebral hemorrhage has its predilection sites: basal ganglia, posterior limb of the internal capsule, area of the fourth ventricle of the cerebellum, and pontine tegmentum. Most of the hemorrhages are probably caused by rupturing of the small end arteries in the setting of chronic hypertension. They produce discrete clinical syndromes often mimicking classic lacunar syndrome, of which pure sensory stroke is relatively common.

Midbrain angioma with disconjugate vertical gaze palsy

Loss of depression in one eye with contralateral loss of elevation is rare. It has been attributed to a subnuclear lesion of the oculomotor nerve nuclear complex. We present a patient with these signs who has an arteriovenous malformation occupying his rostral midbrain. We argue that attributing these findings to a subnuclear lesion of the oculomotor nerve complex does not take into consideration the secondary, vertical action of the obliques.

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.

Vertical gaze palsy and selective unilateral infarction of the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF)

We report a clinico-pathological correlation study in a patient with basilar artery thrombosis, who developed tetraplegia and combined up- and downgaze palsy involving voluntary saccades and visually-guided movements, but sparing the oculocephalic responses. At necropsy, apart from bilateral infarction in the basis pontis, there was a single unilateral infarct selectively destroying the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) on the right. The posterior commissure and its nucleus, the nucleus of Cajal, the nucleus of Darkschewitsch and the pontine tegmentum were spared. We suggest that the unilateral riMLF lesion may have disrupted bilateral upgaze excitatory and inhibitory inputs and unilateral downgaze excitatory inputs. The functional anatomy of inhibitory and excitatory vertical gaze circuitry, which remains speculative, may explain why a unilateral lesion of the upper midbrain tegmentum may be sufficient to generate an upgaze palsy or a combined up- and downgaze palsy, while an isolated downgaze palsy requires bilateral lesions.

Manic delirium and frontal-like syndrome with paramedian infarction of the right thalamus

A disinhibition syndrome affecting speech (with logorrhoea, delirium, jokes, laughs, inappropriate comments, extraordinary confabulations), was the main manifestation of a right-sided thalamic infarct involving the dorsomedian nucleus, intralaminar nuclei and medial part of the ventral lateral nucleus. Resolution of conflicting tasks was severely impaired, suggesting frontal lobe dysfunction. These abnormalities correlated with the finding on SPECT of a marked hypoperfusion in the overlying hemisphere predominating in the frontal region. We suggest that this behavioural syndrome was produced by disconnecting the dorsomedian nucleus from the frontal lobe and limbic system.

Unilateral left paramedian infarction of thalamus and midbrain: a clinico-pathological study

In a patient with a unilateral embolic infarct in the left posterior thalamo-subthalamic paramedian artery territory, neuropathological studies showed involvement of the intralaminar, dorsomedial, and internal part of the ventral posterior nuclei of the thalamus, of the rostral part of the mesencephalic reticular formation, and of the posterior commissure. The patient showed upgaze palsy for voluntary saccades, smooth pursuit and vestibulo-ocular movements, sustained downgaze, right-sided motor hemineglect and facio-brachial hypaesthesia, motor transcortical aphasia and anterograde amnesia. This case confirms that unilateral destruction of the posterior commissure, rostral interstitial nucleus of the MLF and interstitial nucleus of Cajal produces a non-dissociated upgaze palsy. Involvement of the nucleus of Cajal probably produced the sustained downward deviation of the eye, by causing predominance of downward vestibulo-ocular inputs. This case also shows that thalamic aphasia and anterograde amnesia may be related to a paramedian lesion of the thalamus, with special reference to involvement of the dorsomedial nucleus, in the absence of lesion of the pulvinar and mamillo-thalamic tract and of conspicuous involvement of the ventral lateral nucleus. Selective hemineglect for motor tasks may occur in infarction of the dominant thalamus, involving the intralaminar nuclei.

The syndrome of unilateral tuberothalamic artery territory infarction

The study of 3 personal cases and 5 published cases of unilateral infarct limited to the territory of the tuberothalamic artery suggests that this syndrome should be differentiated from the other thalamic syndromes. The onset is usually sudden, with moderate contralateral weakness. Sensory changes may be present but remain mild. The patients are apathetic, show perseveration and may be disoriented. In left-sided infarcts, transcortical aphasia, verbal and visual memory impairment and sometimes acalculia are found. In right-sided infarcts, hemispatial neglect, visual memory impairment and disturbed visuospatial processing are common. A decreased level of consciousness, disturbed ocular movements, severe motor weakness and delayed abnormal movements do not occur. Involvement of the ventral lateral and dorsomedial nucleus with sparing of the intralaminar nuclei, posterolateral formation and upper midbrain may explain this picture. The fact that the tuberothalamic artery arises from the posterior communicating artery, which often receives its supply from the carotid system, further justifies considering unilateral tuberothalamic infarcts as a syndrome.