China
Africa
Explore chapters and articles related to this topic
An Approach to Oculomotor Anomalies in a Child
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
The trochlear nerve nucleus is located in the ventral pontomesencephalic junction caudal to the oculomotor nuclei. The trochlear nerve fascicles cross to innervate the contralateral superior oblique muscle and exit the brainstem dorsally beneath the inferior colliculus. The abducens nucleus resides in the dorsal pons. The abducens nerve fascicles travel ventrally and exit the brainstem at the pontomedullary junction to innervate the ipsilateral lateral rectus muscle.
Diabetic Neuropathy
Published in Jahangir Moini, Matthew Adams, Anthony LoGalbo, Complications of Diabetes Mellitus, 2022
Jahangir Moini, Matthew Adams, Anthony LoGalbo
Common signs and symptoms of cranial neuropathy depend on the nerve affected. In an oculomotor palsy, there will be double vision on lateral and upward gaze with drooping of the eyelid of the affected eye. If the cell body of the third nerve has been affected, bilateral ptosis may also be appreciated. Involvement of the trochlear nerve leads to double vision on vertical gaze and a compensatory head tilt. A diabetic facial nerve palsy leads to loss of the ability to raise the eyebrow, close the eye, raise the corner of the mouth, change in hearing on the affected side, and a loss of taste.
Head and Neck
Published in Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno, Understanding Human Anatomy and Pathology, 2018
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno
The trochlear nerve (CN IV) innervates the superior oblique muscle, which depresses and abducts the eye (Plates 3.14 and 3.33). It runs anteriorly from the brainstem and joins CN III and CN VI before all three nerves enter the orbit through the superior orbital fissure (see Section 3.5.7 for descriptions and actions of the extraocular muscles).
Isolated Sudden-Onset Trochlear Nerve Palsy Associated with Mild Novel Coronavirus Disease (COVID-19) Infection
Published in Journal of Binocular Vision and Ocular Motility, 2023
Mehmet Serhat Mangan, Zeynep Acar
Trochlear nerve palsy is the most common isolated palsy of the extraocular muscles.1 It may not always be possible to differentiate between the congenital and acquired types and an overlap between these two types at presentation can be encountered.1,2 Acquired trochlear nerve palsy is frequently caused by closed head trauma, but uncommonly caused by infarct or tumor compression.1,2 It has rarely been associated with viral infections such as those caused by herpes zoster ophthalmicus,3 herpes simplex-1,4 influenza B,5 human immunodeficiency virus-1,6 human herpesvirus-6,7 and varicella zoster virus.8 We present an otherwise healthy case with isolated trochlear nerve palsy in the setting of a SARS-CoV-2 (COVID-19) infection.
Chameleons, red herrings, and false localizing signs in neurocritical care
Published in British Journal of Neurosurgery, 2022
Boyi Li, Tolga Sursal, Christian Bowers, Chad Cole, Chirag Gandhi, Meic Schmidt, Stephan Mayer, Fawaz Al-Mufti
Trochlear nerve palsy typically presents as binocular diplopia on downward and inward gaze, which can cause a head tilt.21 Population studies have found the most common etiologies to be presumed congenital, hypertension, and trauma, with an incidence of 5.73/100 000/year.22 Given that the trochlear nerve is the thinnest and longest cranial nerve, and the only to emerge from the dorsum of the brain stem, it is the most vulnerable to trauma and other physical stresses.21 Trochlear nerve palsy has also been described as a FLS in IIH, benign intracranial hypertension (BIH), pseudotumor cerebri.3,8,23 Stretching of the nerve fibers due to ICP has been the only proposed mechanism.23 Patients with this FLS may have headache from eye strain, and raised ICP must be suspected if there is no history of head trauma.21 The findings may occur in conjunction with other cranial nerve signs or alone. The palsy may resolve with ICP reduction.3 They are often overlooked, as fourth nerve palsies are more subtle than the other cranial nerve palsies, and it has been suggested that the incidence of false localizing fourth nerve palsies is higher than reported.1,23
Superior oblique palsy: A case report
Published in Cogent Medicine, 2020
Ngozika Esther Ezinne, Kingsley Kenechukwu Ekemiri, Aliyah Khan
The trochlear nerve arises from the trochlear nucleus of the brain, emerging from the posterior aspect of the midbrain (it is the only cranial nerve to exit from the posterior midbrain) (Brazis, 1993). It runs anteriorly and inferiorly within the subarachnoid space before piercing the dura mater adjacent to the posterior clinoid process of the sphenoid bone. The nerve then moves along the lateral wall of the cavernous sinus (along with the oculomotor nerve, the abducens nerve, the ophthalmic and maxillary branches of the trigeminal nerve and the internal carotid artery) before entering the orbit of the eye via the superior orbital fissure. The trochlear nerve innervates the superior oblique, which is a muscle of oculomotion (Kim et al., 2020). The tendon of the superior oblique is tethered by a fibrous structure known as the trochlea, giving the nerve its name. Although the mechanism of action of the superior oblique is complex, in clinical practice it is sufficient to understand that the overall action of the superior oblique is to depress and intort the eyeball (Morillon & Bremner, 2017).