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A Clinical Approach to Abnormal Eye Movements
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Lesions in the neural integrator or the flocculus that stabilizes it result in a deficit in holding the gaze in the eccentric position. This defect in gaze-holding produces a slow drift of the eyes back to the primary position, resulting in a gaze-evoked nystagmus (Figure 18.3). The larger the eccentricity of the gaze, the faster the slow phase velocity. As the eye position becomes less eccentric, there is less drift. This slow drift is corrected by correcting saccades, which brings back the eye to the desired location in the orbit, resulting in nystagmus with fast phase to the point of fixation GEN.
The viva: operative surgery and surgical anatomy
Published in Vivian A. Elwell, Ramez Kirollos, Syed Al-Haddad, Neurosurgery, 2014
Vivian A. Elwell, Ramez Kirollos, Syed Al-Haddad
The flocculus is the smallest lobe of the cerebellum. It is located at the anterior part of the hemisphere, between the biventral lobe and the middle peduncle of the cerebellum, in the line of the horizontal fissure. Boundaries: inferior to cranial nerves VII/VIII and superior to cranial nerves IX/X/XI.
Neuroimaging
Published in Sarah McWilliams, Practical Radiological Anatomy, 2011
o The cerebellum lies in the posterior fossa with two hemi-spheres and a central vermis. If the vermis is absent a large cerebrospinal fluid (CSF) cyst occurs, called a Dandy-Walker cyst. The cerebellum has tonsils inferiorly which should not project through the foramen magnum. Anterolaterally, the cerebellum has a flocculus (Fig. 1.12).
Identification of factors associated with tinnitus outcomes following the microsurgical treatment of vestibular schwannoma patients
Published in Acta Oto-Laryngologica, 2021
Chi Zhang, Fangyuan Wang, Wei Cao, Xiaoyan Ma, Jiyue Chen, Weidong Shen, Shiming Yang
Differences in intraoperative flocculus and paraflocculus treatment may account for these findings, as several studies have provided evidence that the paraflocculus is closely associated with tinnitus. In animal models of chronic tinnitus, increased ipsilateral paraflocculus has been detected. The paraflocculus region plays a role in suppressing unwanted noise, and factors affecting this region may thereby lead to the impairment of this noise suppression mechanism [14]. The flocculus and paraflocculus are always manipulated together during surgery. When microsurgery is performed via the TL approach, the flocculus and paraflocculus are rarely manipulated as the tumor is accessed via the vestibulum. In contrast, they are almost always manipulated when surgery is performed via the RS approach, as they may cover the tumor and vestibulocochlear nerve. This manipulation has the potential to compromise flocculus and paraflocculus functionality, thereby altering postoperative tinnitus status in preTN + patients.
Morphologic characterization of the anterior inferior cerebellar artery: a direct anatomic study
Published in Neurological Research, 2020
L.E. Ballesteros, P.L. Forero, H.Y. Estupiñan
The AICA occlusion results in a syndrome that mainly compromises the cerebral stem and the middle cerebellar peduncle, present in wide clinical presentations that may include: paralysis of the facial and vestibulocochlear nerves caused by the involvement of the nerves and their nuclei; vertigo, nausea, vomiting and nystagmus caused by injuries of the vestibular nuclei and their connections to the nuclei of the decimal cranial nerve, ipsilateral anaesthesia and thermal analgesia on the face and corneal hypoesthesia, caused by interruption of the trigeminal fascicle; Horner’s syndrome determined by the interruption of the descending pupil dilating nerve fibers located on the lateral portion of the pons and the medulla oblongata; hypoesthesia and thermal analgesia in the contralateral hemi body due to compromise of the lateral spinothalamic fascicle [19]; also, cerebellar ataxia and asynergy attributed to a lesion in the lower cerebellar peduncles [4,20–23]. Furthermore, dysarthria, ipsilateral dysmetria may also occur. Additionally, a loss of ipsilateral conjugate gaze as a consequence of flocculus involvement. Finally, it is worth mention that infarctions of the AICA territory are rare and often misdiagnosed [24].
Auditory brainstem implantation (ABI) in children without neurofibromatosis type II (NF2): communication performance and safety after 24 months of use
Published in Cochlear Implants International, 2020
Ranjith Rajeswaran, Mohan Kameswaran
All participants were implanted with MED-EL ABI (PULSAR or CONCERTO) and used an OPUS 2 audio processor. Preoperatively, the meningitis vaccination status of all participants was checked. For a full description of the surgical procedure see Raghunandhan et al. (2018). In short, surgery was done using the retrosigmoid approach. The ABI receiver stimulator coil bed was drilled with tie-down holes. The dura was reflected to visualize the cerebellum and CSF was released. Flocculus and foramen of Luschka was identified. The dummy electrode was negotiated through the foramen of Luschka to floor of the 4th ventricle to check optimal positioning of electrodes, followed by placing the permanent electrode through the same route, after fixing receiver stimulator coil. Electrode placement was done superficial to straight vein. After optimal placement, electrodes were secured with surgical® (Ethicon, Bridgewater, NJ, USA). The dura was closed in a water-tight manner and the craniotomy defect was covered with gel foam and bone sandwich. The receiver-stimulator area was closed with Palva flap and skin wound was closed in layers followed by mastoid dressing.