Head and Neck
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno in Understanding Human Anatomy and Pathology, 2018
Of course, there are also many similarities between the veins and arteries: There is an inferior thyroid artery branching from the subclavian artery and an inferior thyroid vein usually branching from the brachiocephalic vein; the occipital artery is a posterior branch of the external carotid artery and the occipital vein is a posterior branch of the internal jugular vein; the facial vein gives rise to the inferior labial vein, superior labial vein, and angular vein, and the two major superior branches of the superficial venous system of the head are the maxillary veins and the superficial temporal vein, in a configuration very similar to that seen in the arterial system. Note however that the superior ophthalmic vein and the inferior ophthalmic vein run respectively superior and inferior to the eye, the superior ophthalmic vein anastomosing with the angular vein, which is a branch of the facial vein (Plate 3.22). This anastomosis is clinically important because infections of the nasal cavity, cheeks, forehead, and upper lip can be spread via the facial vein through the angular and superior ophthalmic veins to the cavernous sinus, a dural venous sinus in the base of the cranium, and result in thrombosis of this sinus. This condition affects the abducens nerve and, subsequently, the lateral rectus muscle and the movements of the eye.
An Approach to Oculomotor Anomalies in a Child
Vivek Lal in A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
The presentation of an isolated abducens nerve palsy can vary depending on the severity of the paralysis. Patients may present with a small esotropia and face turn, or a large esotropia that precludes fusion in any direction of gaze. Due to the anatomical course of the sixth nerve, several associated symptoms must be sought in order to localize the lesion. In the sixth nerve nucleus, neurons that are destined to climb within the medial longitudinal fasciculus to innervate the contralateral medial rectus muscle for ipsilateral gaze reside. For this reason, a nuclear abducens palsy is typically associated with a gaze palsy in the ipsilateral direction. In addition, nuclear abducens palsies are also almost always associated with facial nerve palsies due to the proximity of the facial nerve nucleus and genu. As the sixth nerve traverses the petrous apex, it can be affected by intracranial pressure changes as well as by skull base tumors. In the cavernous sinus, the oculosympathetic fibers are adjacent to the abducens nerve, and therefore, a co-existent Horner syndrome must be sought.
Complications of Skull Base Surgery
John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed in Paediatrics, The Ear, Skull Base, 2018
The cranial nerves III, IV and VI are at risk during operations of the petrous apex adjacent to the cavernous sinus and the anterior skull base. The trochlear nerve exits the posterior brainstem and has a relatively long intracranial course, but is well protected in the tentorium and is infrequently injured. Abducens nerve palsy has been reported after lumbar drain placement – it is not known whether this is through an ischaemic or traction injury. Abducens nerve palsy management tends to be symptomatic, with recovery tending to be slow and progressive. In paediatric patients occlusive patch therapy for eyes will help avoid amblyopia, until residual palsy improves. Monitoring of extraocular movements is important in recovery.
A Case Report of Bilateral Abducens Palsy in the Setting of Clival Fracture – Recovery Related to Pathophysiological Basis of Injury
Published in Neuro-Ophthalmology, 2021
Stefan Dimou, Lobna Alukaidey, Girish Nair
The course of the abducens nerve from the brainstem to the lateral rectus is long and tortuous, leaving it vulnerable to injury. Emerging from the lower border of the pons, above the medullary pyramid, it travels ventrally through the pontine cistern before turning superiorly to pierce the dura mater along the clivus and courses upwards between the layers of the dura. It then passes through the osteofibrous conduit known as Dorello’s canal at the petrous apex to pass into the cavernous sinus, where it runs adjacent to the cavernous segment of the internal carotid artery before entering the superior orbital fissure (Figure 4). Here it runs through the cone of muscles to enter the ocular surface of the lateral rectus muscle, approximately one-third of the way along.2
Trigeminal schwannoma: a single-center experience with 43 cases and review of literature
Published in British Journal of Neurosurgery, 2021
Mingchu Li, Xu Wang, Ge Chen, Jiantao Liang, Hongchuan Guo, Gang Song, Yuhai Bao
Among the 43 patients, the tumor was totally removed in 39 patients (90.7%) and near-totally removed in three patients (7.0%). In one patient (2.3%), the tumor was only partially removed, because the ICA was injured, and the patient died after the operation. The abducens nerve was damaged in two patients (4.7%), and the nerve function achieved a significant improvement during the follow up. One patient developed mild facial paralysis and two patients developed intracranial infection after the operation. However, all of them achieved complete recovery before discharge. All four patients with trigeminal neuralgia achieved total recovery. However, the facial numbness got relief in only four patients, and this still continued in 24 patients (85.7%). In two patients, facial numbness even aggravated after the operation. For the nine patients with preoperative trigeminal motor impairment, the symptom did not achieve relief in any patient. Patients with oculomotor nerve paralysis, abducent paralysis and hearing decrease also achieved significant improvement during the follow-up. At a median of 45.3 ± 25.5 months (6–84 months) of follow up, the tumor recurred in only one patient, and this patient received a second operation via FTSA. The surgical results and follow-up results are shown in Table 4.
A Potentially Adjustable Modification of the Nishida Procedure
Published in Journal of Binocular Vision and Ocular Motility, 2023
Robert Tauscher, Mathew Haynie, Stacy L. Pineles, Federico G. Velez
In patients with complete, chronic abducens nerve palsies and absent abduction, the treatment of choice is often a transposition procedure. Many different variations of such procedures, which replace a portion the abducting force by redirecting one or more of the remaining extraocular muscles, have been described and utilized.1,2 One of the more recently developed variations, first described3 (and subsequently modified4 by Nishida and colleagues, transposes the superior rectus (SR) and inferior rectus (IR) laterally without disinserting or splitting either muscle. Good results have been reported.5 However, the possibility of inducing a vertical or torsional deviation, especially if tension on the SR and IR is asymmetric, remains a concern. Being able to adjust the tension and displacement of both muscles post-operatively in the case of a symptomatic deviation could be beneficial.
Related Knowledge Centers
- Abducens Nucleus
- Fourth Ventricle
- Lateral Rectus Muscle
- Oculomotor Nucleus
- Cranial Nerves
- Extraocular Muscles
- Gaze
- Somatic
- Efferent Nerve Fiber
- Facial Colliculus