Paramedian Pontine Tegmentum Research Articles

A case of cardioembloic stroke with wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) syndrome

Here, we report a case of an 85-year-old man who presented sudden onset of diplopia, dysarthria, and gait disturbance. On admission, he exhibited bilateral adduction palsy, convergence palsy, and binocular exotropia in the forward gaze showing wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) syndrome. He had a history of chronic nonvalvular atrial fibrillation. DWI-MRI revealed acute ischemic lesions in the paramedian pontine tegmentum, lower midbrain, both cerebellar hemispheres, and left frontal cortex. He was thus diagnosed with an acute phase of cardioembolic stroke. Subsequently, the right eye adduction palsy in the forward gaze was slightly improved, but other eye movement disorders persisted during discharge from the hospital. The pathology was suspected to involve bilateral damages to both medial longitudinal fasciculus and the paramedian pontine reticular formation. WEBINO syndrome was not only ascribed to lacunar infarction and large artery atherosclerosis but also cardioembolic stroke. The presence of other non-eye symptoms and multiple ischemic lesions could be the characteristics of WEBINO syndrome following cardioembolic stroke.

Do the paramedian tract neurons in pons take a role as a vertical neural integrator in humans?

Impairment of gaze holding mechanism and gaze-evoked nystagmus (GEN) in the vertical plane due to a focal brain lesion is usually caused by a failure of the vertical neural integrator, which is known to be localized in the interstitial nucleus of the Cajal in the upper midbrain. We report a patient with hemorrhagic stroke involving the paramedian pontine tegmentum who presented with vertical GEN due to a failure of vertical gaze holding mechanism and unilateral internuclear ophthalmoplegia. The possible structure taking a role as a vertical neural integrator in this patient might be the paramedian tract (PMT) neuron.

Ｏｎｅ‐ａｎｄ‐ａ‐ｈａｌｆ症候群ならびに顔面神経麻痺で発症した多発性硬化症例

A 35-year-old man who was referred to our hospital 6 days after diplopia, dizziness and left hemifacial palsy had experienced left facial palsy 8 years earlier. Ocular movement showed typical left one-and-a-half (OAH) syndrome; conjugate left-side lateral gaze palsy and impaired left-eye adduction and for the right eye, gaze nystagmus induction in the right-side gaze. Vertical eye movement and convergence were not disturbed. Pure-tone audiometry, auditory brain stem response (ABR) and vestibular evoked myogenic potential (VEMP) were within the normal range, while caloric tests showed canal paresis on both sides. T2-weighted magnetic resonance imaging (MRI) showed multiple high-intensity lesions in the paramedian pontine tegmentum and white matter close to the lateral ventricles, yielding a diagnosis of multiple sclerosis based on recurrent facial palsy and multiple lesions seen on MRI. Methylpredonisolone pulse therapy effectively removed left facial palsy completely within a week and ocular movement had normalized one month later. Careful evaluation of eye movement is a key in suspected brain lesion symptoms such as multiple sclerosis presenting a variety of neurological signs and symptoms.

ＷＥＢＩＮＯ症候群を呈した多発性硬化症の１例

We report a 50-year-old man presenting with wall-eyed bilateral internuclear opthalmoplegia (WEBINO) syndrome. He had suffered from progressive double vision and tetraparesis, and been diagnosed as secondary progressive multiple sclerosis (MS). On admission, he presented with bilateral facial nerve palsy, pseudobulber palsy, and spastic tetraparesis, predominantly on the right side. Bilateral adduction deficits were noted on horizontal gaze, together with nystagmus of abducting eyes. On primary eye position, the right eye was fixed in the midposition, while the left eye was exotropic. The right eye was deviated outward on fixation with the left eye. Vertical gaze and convergence were preserved. These ocular findings were compatible with WEBINO and considered to result from impairment of bilateral medial longitudinal fasciculus and imbalance of paramedian pontine reticular formation on both sides. T2-weighted images of MRI revealed a high signal lesion in the paramedian pontine tegmentum without enhancement. He underwent steroid pulse therapy, followed by mild improvement in adduction of both eyes. Although WEBINO tends to be observed in the acute stage of stroke, this patient suggests that demyelinative lesions of MS can cause persistent WEBINO, involving the paramedian pontine tegmentum.

Body lateropulsion as an isolated or predominant symptom of a pontine infarction

Background: Lateropulsion of the body—that is, falling to one side—is a well-known clinical feature of stroke in the posterior circulation. Body lateropulsion as an isolated or predominant manifestation of a...

Regional distribution of functions in dorsolateral prefrontal cortex of the monkey

Single-cell responses were obtained from 352 neurons in dorsolateral prefrontal cortex (Walker's areas 9 and 46) of three monkeys. The neurons were classified functionally according to their responsiveness to visual, auditory and somatosensory stimulation, and to correlation of their activity with spontaneous eye or limb movements. A comparison between the distribution of different functions and known modality-specific anatomical connections to various sectors of this area showed a good correspondence. On average somatosensory and motor neurons were located more ventrally than the remaining ones, and were concentrated to the middle third of the inferior bank of principal sulcus and adjacent inferior convexity, where a number of somatosensory projections overlap. Oculomotor neurons were found caudally in both banks of principal sulcus and in a narrow band on the dorsal convexity, coinciding with the projection fields of areas 7a and 7ip of posterior parietal cortex, superior colliculus, and paramedian pontine tegmentum. Other functions were scatteredly distributed. Visual neurons which preferred moving to stationary stimuli were located more caudally and dorsally than other visual neurons. The present study shows that a parcellation of dorsolateral prefrontal cortex proposed on the basis of anatomical connectivity is also functionally evident.

Die Internukleäre Ophthalmoplegie der Abduktion nach Lutz („hintere” INO) - ein sinnvolles Syndrom?

The syndrome of internuclear ophthalmoplegia of abduction is analysed against the background of updata concepts on the organisation of the oculomotor system in the brainstem. Since the system cannot be satisfactorily characterised, neither phenomenologically nor topically or theoretically, it is suggested to abandon the postulate of an independent syndrome of internuclear ophthalmoplegia of abduction and to replace it by the anatomic descriptive term of a paramedian pontine tegmentum syndrome.

Benign cyst of the paramedian pontine tegmentum

A benign ovoid cyst, without an epithelial lining, localized in the paramedian pontine tegmentum, was examined by computed tomography (CT) and magnetic resonance imaging (MRI) (25 x 15 x 15 mm) and successfully operated upon. The one-and-a-half syndrome (horizontal gaze palsy to the right and paralysis of adduction of the right eye) and ipsilateral "peripheral" VII nerve palsy dominated the clinical picture. Fenestration, 5 mm in diameter, of the cyst wall through the floor of the IV ventricle was performed and 2.6 ml of clear, colorless fluid was evacuated. Inspection of the cyst, using the operating microscope, revealed a smooth, white, glistening cavity with no evidence of other pathological tissue. Duraplasty was performed with allogenic pericardium. Neurological symptoms improved immediately after surgery. Light and electron microscopy of the cyst wall revealed a fibrillar astroglial network and fragments of ependyma at the ventricular side of the biopsy.

Cheiro-oral syndrome with bilateral oral involvement: a study of pontine lesions by high-resolution magnetic resonance imaging.

Two cases of unusual cheiro-oral syndrome due to small pontine haemorrhage are described, in which both sides of the mouth were involved in the initial stage. High resolution magnetic resonance imaging revealed a small lesion at the paramedian pontine tegmentum in both cases and suggested involvement of the medial portion of the medial lemniscus.

Afferent projections to the cerebellar flocculus in the pigmented rat demonstrated by retrograde transport of horseradish peroxidase.

The horseradish peroxidase (HRP) retrograde transport method was used to identify brainstem afferents to the cerebellar flocculus in the pigmented rat. Injections of the enzyme were made through recording microelectrodes, making it possible to localize the injection site by physiological criteria. Clearly, the largest number of afferents arise from the bilateral vestibular and perihypoglossal nuclei and from the contralateral dorsal cap (of Kooy) of the inferior olive. Additionally, a substantial number arise bilaterally from: (1) the nucleus reticularis tegmenti pontis (NRTP); (2) several of the cranial motor nuclei including the abducens, retrofacial and facial nuclei and the nucleus ambiguus; (3) the rostral part of the lateral reticular nucleus (subtrigeminal nucleus); (4) the raphe pontis and raphe magnus and (5) neurons intercalated among the medial longitudinal fasciculus (MLF) just rostral to the hypoglossal nucleus and another group rostral to the abducens nucleus. The basilar pontine nuclei contained a large number of lightly labeled neurons in all flocculus injections which were discretely located within the dorsolateral, lateral and medial divisions. These areas were labeled bilaterally but with a slight contralateral preponderance. Injection into the flocculus, but involving the adjacent ventral paraflocculus, produced a heavier labeling of pontine neurons with a slightly different distribution. Therefore, we tentatively conclude that the flocculus receives input from these pontine visual centers (dorsolateral, lateral and medial nuclei), perhaps through collateral projections from neurons projecting to the paraflocculus. The present study demonstrates strong similarities between the rat and other species studied (e.g., rabbit, cat, monkey) in terms of the brainstem nuclei projecting to the flocculus. Most noticeable in quantitative terms are the pathways known to mediate vestibular (vestibular and perihypoglossal nuclei) and visual (optokinetic) information (e.g., NRTP). Additionally, we can provide morphological evidence that the midline and paramedian pontine tegmentum, identified in the cat and monkey as containing saccade-related neurons, send large numbers of projections to the rat flocculus. Given these similarities, the rat may be a suitable animal model in which to study the pathways underlying visual-vestibular interaction and saccadic mechanisms in the flocculus.

Juvenile Primary Pontine Hemorrhage

A 12-year-old boy was admitted in a comatose state following a sudden episode of headache and vomiting. General physical examination and vital signs at admission were normal. A difference was noted in pupil sizes, the right being slightly larger, and light reactions of both pupils were sluggish. Bilateral deep tendon reflexes were exaggerated and decerebrate posturing was elicited by noxious stimuli. There was right hemiparesis, but facial palsy was not be observed. A lumbar tap revealed an opening pressure of 230 mm H2O and the fluid was bloody. Ventricular drainage was performed the following day. Conray ventriculography showed a filling defect in the posterior end of the third ventricle, but the aqueduct of Sylvius and the fourth ventricle were not visualized. Computed tomography (CT) revealed the presence of a high density lesion in the area between the left paramedian pontine tegmentum and the fourth ventricle. It was diagnosed as a primary pontine hemorrhage, and a ventriculo-peritoneal shunt was performed. Left vertebral angiography failed to show any abnormal findings such as vascular malformation. Ten days after admission, anisocoria disappeared. The patient's consciousness became clear one month after the onset. With improvement of the level of consciousness, the following abnormal neurological findings were noted. Ocular movement indicated the presence of the one-and-a-half syndrome, i.e., complete loss of horizontal movement of both eyes except for lateral gaze of the right eye accompanied by nystagmus. There were left peripheral facial palsy and right hemiparesis with exaggerated deep tendon reflexes plus a right Babinski response. Right hemiparesis improved after about one year. A CT scan performed two years after the onset revealed a non-enhanced low density area in the pontine tegmentum where the hematoma had been located. At present, the patient is in good health and attending junior high school.

Direct and indirect preoculomotor pathways of the brainstem: an autoradiographic study of the pontine reticular formation in the cat.

AbstractThe efferent connections of the paramedian pontine reticular formation have been studied in the cat in autoradiographic experiments designed to analyze direct and indirect preoculomotor pathways. Injections of tritium‐labelled amino acids were placed (1) near the border between the oral and caudal subdivisions of the nucleus pontis centralis, (2) in more rostral and dorsal parts of the pontine tegmentum, (3) at the pontomesencephalic border, and (4) at the pontomedullary border.Tegmental injections of the first group were unique in labelling a direct ipsilateral pathway to the abducens nucleus and nucleus prepositus hypoglossi. More rostral injections failed to produce discrete labelling of the nuclei of the extraocular muscles but labelled nearby tegmentum and central gray substance. Caudal deposits, involving the pontomedullary reticular formation at its junction with the abducens, perihypoglossal and vestibular nuclei, labelled a decussating fiber system reaching the contralateral abducens nucleus, nucleus prepositus hypoglossi and parts of the vestibular complex. In a single additional case, an injection placed in the oculomotor complex produced heavy labelling of the abducens nuclei.All tegmental injections labelled discrete reticulo‐reticular and other variably complex longitudinal pathways. Most injections of (a) the pontomedullary and (b) the pontomesencephalic zones elicited labelling of the pretectum including the nucleus of the optic tract. An incidental finding in the latter group was dense labelling of the pars compacta of the substantia nigra, subthalamic nucleus, and (1 case) entopeduncular nucleus; in one case of each of these groups, labelled fibers were traced to the external pallidum.These observations suggest that, with respect to its efferent oculomotor affiliations, the paramedian pontine tegmentum may be divided into compartments whose supranuclear connections are distinct but for the most part heavily weighted toward influencing the abducens nucleus and periabducens region. Considered within the framework of behavioral and physiological studies of the so‐called pontine gaze center, and studies of pontine afferents, the findings are interpreted as suggesting a functional differentiation of these tegmental zones with respect to their influence on eye‐head coordination.

Motor excitation and inhibition in internuclear palsy. An electromyographic study.

INTERNUCLEAR ophthalmoplegia is the hallmark of a lesion in the paramedian pontine tegmentum. 1-3 It implies distinctive disturbances in patterns of ocular motor innervation. Electromyography (EMG) was used in six patients with acute and chronic internuclear ophthalmoplegia to display and analyze these altered patterns of motor excitation and inhibition during various types of horizontal gaze. All were patients at the University of California San Francisco Medical Center. Method Conjunctival topical anesthesia was used. Fine concentric needle electrodes were inserted into the involved medial rectus (MR) and one or more of the other three horizontal rectus muscles and were gently manipulated until the recording tips were securely within the belly of the muscle. The electronic system used for recordings from these muscles is standard for EMG and has been described previously. 4 Several types of horizontal eye movements were studied: (1) following movements to the extremes of lateral gaze, (2)