Project description:Pseudo-spontaneous nystagmus has been reported in patients with direction-changing positional nystagmus (DCPN). Recently, the concept of a "light cupula" has been introduced as a pathophysiology that can exhibit persistent geotropic DCPN. Patients with persistent DCPN could have different characteristics of nystagmus. Therefore, we investigated the pseudo-spontaneous nystagmus in patients with transient (canalolithiasis) and persistent (belong to light cupula theory) geotropic DCPN.In this study, prospectively, 49 patients with persistent geotropic DCPN and 67 patients with transient geotropic DCPN were enrolled. We compared the incidence of pseudo-spontaneous nystagmus between persistent and transient DCPN patients and characteristics of pseudo-spontaneous nystagmus and positional nystagmus by the head roll test in these patients. A prospective study was conducted at a dizziness clinic.Patients with persistent geotropic DCPN exhibited significantly higher incidence of pseudo-spontaneous nystagmus than patients with transient geotropic DCPN. Patients with transient DCPN showed a significantly higher mean SPV value during the head roll test than patients with persistent DCPN. All patients exhibiting pseudo-spontaneous nystagmus in patients with persistent DCPN had a null plane, and all patients had nystagmus beats to the opposite side of the null plane or the lesion side.Our results support the possibility that the mechanism between persistent and transient geotropic DCPN may be different. However, more studies are needed on the pathogenesis and mechanism of the two diseases, including the occurrence of pseudo-spontaneous nystagmus in the disease entity.
Project description:Background and purposeThis study aimed to determine the clinical features, diagnosis, and treatment of patients with persistent geotropic (pG) and persistent apogeotropic (pAG) direction-changing positional nystagmus (DCPN).MethodsThis retrospective study included 30 patients with pG-DCPN and 44 patients with pAG-DCPN. All patients underwent neurological and neurotological examinations, including an evaluation of gaze-evoked nystagmus, eye-movement tests, and assessments of limb ataxia and balance, as well as magnetic resonance imaging to exclude central causes. The characteristics of positional nystagmus were detected using the supine roll test (SRT) and bow-and-lean test (BLT). The null point (NP) at which the nystagmus disappeared was determined. All patients were treated with the barbecue maneuver, and treatment efficacy was evaluated immediately, 1 week, and 1 month after treatment.ResultsThe history of diseases associated with atherosclerosis, peripheral vestibular disorders, otological disease, and migraine differed significantly between patients with pG-DCPN and pAG-DCPN. The affected sides of persistent horizontal DCPN can be determined using the SRT and the BLT, while determining the second NP and vestibular function as well as performing an audiological evaluation can be used to assist in identifying the affected side. The efficacy rates immediately and 1 week after treatment with the barbecue maneuver were higher in patients with pAG-DCPN than in patients with pG-DCPN.ConclusionspAG-DCPN was more compatible with the characteristics of cupulolithiasis, and pG-DCPN was more likely to be associated with a light cupula rather than canalolithiasis. pAG-DCPN was more likely to be accompanied by a disease associated with atherosclerosis, while pG-DCPN was often accompanied by autoimmune-related diseases and a history of migraine. The associations between pAG-DCPN, pG-DCPN, and the above-mentioned diseases need to be clarified further. The canalith-repositioning maneuver was effective in patients with pAG-DCPN and ineffective in patients with pG-DCPN, but most cases of pG-DCPN are self-limiting.
Project description:The aim of this study was to investigate the clinical characteristics and underlying pathogenesis of episodic vestibular syndrome (EVS) with hyperventilation-induced downbeat nystagmus (HV-DBN).
Project description:RationaleVestibular paroxysmia (VP) is characterized by spontaneous, recurrent, short, paroxysmal attacks of vertigo with or without tinnitus.Patient concernsWe report a case of paroxysmal recurrent vertigo accompanying clicking tinnitus on the left side in a 61-year-old patient. He had undergone microvascular decompression to treat the left-side hemifacial spasm 6 years prior. The patient first developed vertigo attacks about 3 years after microvascular decompression, and the attacks increased in frequency over the last 4 months. Video-nystagmography revealed a background right-beating nystagmus which was reversed every 55 seconds, to left-beating nystagmus for 17 seconds.DiagnosisBrain magnetic resonance imaging and angiography demonstrated a compression of the cisternal segment of the left vestibulocochlear nerve between the tortuous right vertebral artery and the posterior wall of the left porus acusticus internus.Interventions and outcomesUnder the diagnosis of VP, 300 mg oxcarbazepine was administered daily, which relieved the symptoms dramatically.LessonThe neurovascular cross-compression of the vestibulocochlear nerve by the contralateral vertebral artery tortuosity can cause VP. Periodic paroxysms of right-beating nystagmus accompanying the left-side tinnitus during vertigo attacks in our patient can be explained by secondary central hyperactivity in both vestibular and cochlear nuclei following long-standing neurovascular cross-compression.
Project description:Vestibular paroxysmia (VP) is a disorder encountered in the pediatric population that etiology has been attributed to neurovascular cross-compression syndrome (NVCC). The purpose of this study was to report a new probable pathological condition, the narrowed internal auditory canal (IAC), which appears to be involved in the development of a clinical picture of VP in the pediatric population. A retrospective descriptive comparative study was conducted to compare clinical, electrophysiological, radiological, and therapeutic outcomes in both etiologies. Overall, 16 pediatric patients suffering from VP were included and divided into two groups: patients with narrowed internal auditory (Group 1) were compared to those with NVCC syndrome (Group 2). Patients in both groups were similar in terms of auditory complaints, as well as hearing, vestibular, and electrophysiological status. A narrowed IAC was encountered in the adolescent age category and females, especially those with rapid growth. The diagnosis requires a careful analysis of the shape and diameters of the IAC. Radiologic measurements in the axial plane do not seem to be sufficient to confirm the diagnosis, and, therefore, an analysis of diameters in the coronal plane is required. Treatment with sodium-channel blockers drugs showed promising results not only by relieving vertigo but also by normalizing the electrophysiological findings. In conclusion, a narrowed IAC can be considered in patients suffering from VP.
Project description:We review current pharmacological treatments for peripheral and central vestibular disorders, and ocular motor disorders that impair vision, especially pathological nystagmus. The prerequisites for successful pharmacotherapy of vertigo, dizziness, and abnormal eye movements are the "4 D's": correct diagnosis, correct drug, appropriate dosage, and sufficient duration. There are seven groups of drugs (the "7 A's") that can be used: antiemetics; anti-inflammatory, anti-Ménière's, and anti-migrainous medications; anti-depressants, anti-convulsants, and aminopyridines. A recovery from acute vestibular neuritis can be promoted by treatment with oral corticosteroids. Betahistine may reduce the frequency of attacks of Ménière's disease. The aminopyridines constitute a novel treatment approach for downbeat and upbeat nystagmus, as well as episodic ataxia type 2 (EA 2); these drugs may restore normal "pacemaker" activity to the Purkinje cells that govern vestibular and cerebellar nuclei. A limited number of trials indicate that baclofen improves periodic alternating nystagmus, and that gabapentin and memantine improve acquired pendular and infantile (congenital) nystagmus. Preliminary reports suggest suppression of square-wave saccadic intrusions by memantine, and ocular flutter by beta-blockers. Thus, although progress has been made in the treatment of vestibular neuritis, some forms of pathological nystagmus, and EA 2, controlled, masked trials are still needed to evaluate treatments for many vestibular and ocular motor disorders, including betahistine for Ménière's disease, oxcarbazepine for vestibular paroxysmia, or metoprolol for vestibular migraine.
Project description:We designed a prospective study to evaluate changes in tinnitus after vestibular schwannoma (VS) surgery. Subjects included 41 patients who were diagnosed with a VS and underwent translabyrinthine microsurgery (TLM) between January 2015 and May 2016. All patients underwent related examinations and were asked to answer the Tinnitus Handicap Inventory (THI) scale and a visual analog scale (VAS) of tinnitus severity both pre- and postoperatively. Of the 41 patients, 31 (75.6%) suffered from tinnitus before surgery. Microsurgery was associated with an overall decrease in tinnitus (p?<?0.001). There was a significant improvement in THI and VAS scores after surgery (p?=?0.001 and p?=?0.005, respectively). The decrease in THI scores in the low-frequency group was significantly larger than that of the mid- and high-frequency groups after surgery (p?=?0.034 and p?=?0.001, respectively). The loudness of tinnitus decreased significantly after surgery (p?=?0.031). Tinnitus in patients with VS improved after TLM. Patients with mid-/high-frequency tinnitus and louder tinnitus preoperatively seemed to have a worse prognosis than those with low-frequency and quieter tinnitus.
Project description:Acquired periodic alternating nystagmus (PAN) describes a horizontal jerk nystagmus that reverses its direction with a predictable cycle, and is thought to arise from lesions involving the brainstem and cerebellum. We report a 20-year-old patient with PAN who presented with an acute vertiginous episode and developed an involuntary head movement that initially masked the PAN. The involuntary head movements were abolished with a subtherapeutic dose of botulinum toxin to the neck muscles. We propose that the head movements initially developed as a compensatory movement to the nystagmus, to maintain visual fixation in the presence of the underlying nystagmus, and became an entrained involuntary behavior. This case highlights the importance of disambiguating psychogenic from organic pathology as this may have clinical therapeutic implications, in this case resolution of the most disabling symptom which was her head oscillations, leading to improved day-to-day function despite PAN.
Project description:Many bacteria can rapidly traverse surfaces from which they are extracting nutrient for growth. They generate flat, spreading colonies, called swarms because they resemble swarms of insects. We seek to understand how members of any dense swarm spread efficiently while being able to perceive and interfere minimally with the motion of others. To this end, we investigate swarms of the myxobacterium, Myxococcus xanthus. Individual M. xanthus cells are elongated; they always move in the direction of their long axis; and they are in constant motion, repeatedly touching each other. Remarkably, they regularly reverse their gliding directions. We have constructed a detailed cell- and behavior-based computational model of M. xanthus swarming that allows the organization of cells to be computed. By using the model, we are able to show that reversals of gliding direction are essential for swarming and that reversals increase the outflow of cells across the edge of the swarm. Cells at the swarm edge gain maximum exposure to nutrient and oxygen. We also find that the reversal period predicted to maximize the outflow of cells is the same (within the errors of measurement) as the period observed in experiments with normal M. xanthus cells. This coincidence suggests that the circuit regulating reversals evolved to its current sensitivity under selection for growth achieved by swarming. Finally, we observe that, with time, reversals increase the cell alignment, and generate clusters of parallel cells.