Understanding Parinaud’s Syndrome

Parinaud’s syndrome involves dysfunction of the structures of the dorsal midbrain. We investigated the pathophysiology related to the signs and symptoms to better understand the symptoms of Parinaud’s syndrome: diplopia, blurred vision, visual field defects, ptosis, squint, and ataxia, and Parinaud’s main signs of upward gaze paralysis, upper eyelid retraction, convergence retraction nystagmus (CRN), and pseudo-Argyll Robertson pupils. In upward gaze palsy, three structures are disrupted: the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), interstitial nucleus of Cajal (iNC), and the posterior commissure. In CRN, there is a continuous discharge of the medial rectus muscle because of the lack of inhibition of supranuclear fibers. In Collier’s sign, the posterior commissure and the iNC are mainly involved. In the vicinity of the iNC, there are two essential groups of cells, the M-group cells and central caudal nuclear (CCN) group cells, which are important for vertical gaze, and eyelid control. Overstimulation of the M group of cells and increased firing rate of the CCN group causing eyelid retraction. External compression of the posterior commissure, and pretectal area causes pseudo-Argyll Robertson pupils. Pseudo-Argyll Robertson pupils constrict to accommodation and have a slight response to light (miosis) as opposed to Argyll Robertson pupils were there is no response to a light stimulus. In Parinaud’s syndrome patients conserve a slight response to light because an additional pathway to a pupillary light response that involves attention to a conscious bright/dark stimulus. Diplopia is mainly due to involvement of the trochlear nerve (IVth cranial nerve. Blurry vision is related to accommodation problems, while the visual field defects are a consequence of chronic papilledema that causes optic neuropathy. Ptosis in Parinaud’s syndrome is caused by damage to the oculomotor nerve, mainly the levator palpebrae portion. We did not find a reasonable explanation for squint. Finally, ataxia is caused by compression of the superior cerebellar peduncle.

Central Ocular Motor Disorders: Clinical and Topographic Anatomical Diagnosis, Syndromes and Underlying Diseases

The key to the diagnosis of ocular motor disorders is a systematic clinical examination of the different types of eye movements, including eye position, spontaneous nystagmus, range of eye movements, smooth pursuit, saccades, gaze-holding function, vergence, optokinetic nystagmus, as well as testing of the function of the vestibulo-ocular reflex (VOR) and visual fixation suppression of the VOR. This is like a window which allows you to look into the brain stem and cerebellum even if imaging is normal. Relevant anatomical structures are the midbrain, pons, medulla, cerebellum and rarely the cortex. There is a simple clinical rule: vertical and torsional eye movements are generated in the midbrain, horizontal eye movements in the pons. For example, isolated dysfunction of vertical eye movements is due to a midbrain lesion affecting the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), with impaired vertical saccades only or vertical gaze-evoked nystagmus due to dysfunction of the Interstitial nucleus of Cajal (INC). Lesions of the lateral medulla oblongata (Wallenberg syndrome) lead to typical findings: ocular tilt reaction, central fixation nystagmus and dysmetric saccades. The cerebellum is relevant for almost all types of eye movements; typical pathological findings are saccadic smooth pursuit, gaze-evoked nystagmus or dysmetric saccades. The time course of the development of symptoms and signs is important for the diagnosis of underlying diseases: acute: most likely stroke; subacute: inflammatory diseases, metabolic diseases like thiamine deficiencies; chronic progressive: inherited diseases like Niemann-Pick type C with typically initially vertical and then horizontal saccade palsy or degenerative diseases like progressive supranuclear palsy. Treatment depends on the underlying disease. In this article, we deal with central ocular motor disorders. In a second article, we focus on clinically relevant types of nystagmus such as downbeat, upbeat, fixation pendular, gaze-evoked, infantile or periodic alternating nystagmus. Therefore, these types of nystagmus will not be described here in detail.

Wall-eyed bilateral internuclear ophthalmoplegia in posterior circulation stroke-a case report

Internuclear ophthalmoplegia is characterised by restricted ocular motility in lateral gaze in which the affected eye shows impairment of adduction and it results from damage to medial longitudinal fasciculus (MLF). Wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) is an extremely rare neurological manifestation which has typical signs including primary gaze exotropia, vertical gaze palsy, ptosis, abducting nystagmus. The common and serious etiological factor is cerebrovascular accident involving the vessels supplying MLF and many cases have life threatening associated neurological impairment. In this case report we have discussed about a gentleman who presented with bilateral ptosis, primary gaze exotropia and headache. Patient found to have vertical gaze palsy and abducting nystagmus on examination. Computed tomography (CT) imaging shows infarct in pontine region and CT angiography revealed basilar artery occlusion supplying region of pons with involvement of posterior cerebral artery. Patient treated with antiplatelet and diplopia managed. Patient showed improvement on subsequent follow-up visits.

A potential new brainstem reflex: The oculoglossal phenomenon

Background: A synchronized involuntary movement of the tongue to the same side as voluntary movements of the eyes, termed the oculoglossal phenomenon, has been observed. A description of the hypothesized pathway of this phenomenon could guide the development of a rapid clinical evaluation of the long segment of the brainstem and help facilitate further studies to establish a new reflex, if possible. The aim of this study is to describe and propose the simple concept of this pathway/phenomenon, the oculoglossal phenomenon. Methods: This is an observational study. Of a newly observe brainstem phenomenon evaluated on a subject at the National Neuroscience Institute in king Fahad Medical City (KFMC), Riyadh, Saudi Arabia. After being observed incidentally in a single patient, 60 participants were tested between January and March 2020 to confirm the presence of the phenomenon. Each subject was instructed to protrude the tongue and then move their eyes horizontally to the side. If the tongue simultaneously and involuntarily moved to the same side as the eyes, the test was deemed confirmatory. A literature review was performed, and possible anatomical pathway was proposed. Results: The oculoglossal reflex was present in most (50/60, 83.3%) of the subjects. Our proposed pathway begins at the frontal cortex, followed by a projection to the paramedian pontine reticular formation, then to the contralateral medial longitudinal fasciculus and bilaterally to the hypoglossal nuclei. Conclusion: An accurate description of this phenomenon could lead to additional studies and possibly establishing it as a legitimate reflex, thus conceivably adding a new tool in the neurological examination to evaluate the brainstem’s integrity.

A Case Report of Classical eight-and-a-Half Syndrome and Etiology Analysis

Eight-and-a-half syndrome is one-and-a-half syndrome plus ipsilateral seventh (facial) cranial nerve palsy, which was first reported by Eggenberger in 1998. This syndrome is caused by a lesion (most often vascular or demyelinating) in the dorsal tegmentum of the caudal pons. It involves the para pontine reticular formation and the medial longitudinal fasciculus, as well as the nucleus and the fasciculus of the facial nerve. We describe a case of a 56-year-old man presented with eight-and-a-half syndrome. We also discuss the vascular pathology and etiology of this syndrome through the literature review. Most eight-and-a-half syndrome cases are caused by occlusions of the perforating branches of the pons. The pathology can be transparent lipid-like changes at the perforator arteries. It can also be thrombosis at the orifice of the main or perforator arteries. BAH could be a very important factor in perforator artery infarction at the pontine. The etiology is closely related to hyperglycemia. An effective intervention is to avoid bad habits and control the hyperglycemia.

Eight and a Half Syndrome: A Rare Case of Pontine Infarction

Introduction: This case report describes “one-and-a-half” syndrome with supranuclear facial palsy. Case: 39 years old male hypertensive patient presented with right facial nerve palsy, internuclear ophthalmoplegia and conjugate gaze palsy. Neuroimaging showed acute posterior pontine infarct at medial longitudinal fasciculus, paramedian pontine reticular formation, abducens nerve nucleus and seventh nerve fascicular zone. Observation: “One-and-a-half”syndrome is characterized by a lateral gaze palsy in one direction and internuclear ophthalmoplegia in the other. Our patient had Right sided one and a half syndrome along with the right facial nerve palsy. Conclusion: Eight and a half syndrome is a rare manifestation of pontine infarction.

An Anatomic, Imaging, and Clinical Review of the Medial Longitudinal Fasciculus

The medial longitudinal fasciculus (MLF) is a paired, highly specialized, and heavily myelinated nerve bundle responsible for extraocular muscle movements, including the oculomotor reflex, saccadic eye movements an smooth pursuit, and the vestibular ocular reflex. Clinically, lesions of the MLF are classically associated with internuclear ophthalmoplegia. However, clinical manifestations of a lesion in the MLF may be more complex and variable. We provide an overview of the neuroanatomy, neurologic manifestations, and correlative examples of the imaging findings on brain MRI of MLF lesions to provide the clinician and radiologist with a more comprehensive understanding of the MLF and potential clinical manifestations for an MLF lesion.

Two Multiple Sclerosis Relapses Affecting the Left Pontine-Mesencephalic Transition and Later the Right Mid Pons, With Distinct Eye Movement Abnormalities - The Importance Of Semiology Above Medical Imaging: Case Report

The authors report the case of a 22-year-old female patient who presented with two distinct relapses of multiple sclerosis. The first was a lesion in the dorsal paramedian pontine area to the left, and the second, not visible in the MRI but presumably affecting the right medial longitudinal fasciculus, in the pons. In both cases, the semiology was unquestionable and compatible to the proposed areas of demyelination, with the patient fully recovering her eye movements after pulses of methylprednisolone.