1/37. Acquired convergence-evoked pendular nystagmus in multiple sclerosis.Nystagmus seen only with convergence is unusual. We describe four cases of acquired convergence-evoked pendular nystagmus in patients with multiple sclerosis. The nystagmus was horizontal and asymmetric in all patients. Eye movement recordings in one subject showed a conjugate rather than a convergent-divergent relationship of the phase of movement between the two eyes. All patients had evidence of optic neuropathy and cerebellar dysfunction. Occlusion of either eye during fixation of near targets led to divergent drift of the covered eye and a decrease in nystagmus. Intravenous scopolamine reduced nystagmus in one patient. Base-in prisms alleviated symptoms of oscillopsia at near and improving reading visual acuity. Convergence-evoked pendular nystagmus may be more common than currently appreciated, particularly among patients with multiple sclerosis.- - - - - - - - - - ranking = 1keywords = near (Clic here for more details about this article) |
2/37. The incidence and waveform characteristics of periodic alternating nystagmus in congenital nystagmus.PURPOSE: To investigate the incidence and waveform characteristics of periodic alternating nystagmus, (PAN) in congenital nystagmus (CN). methods: In a prospective study, 18 patients with CN without associated sensory defects agreed to undergo eye movement documentation using binocular infrared oculography. Two of the 18 had a diagnosis of suspected PAN before entering the study. The patients sat in a dimly lit room and viewed an LED (4 min in diameter) located in the primary position, at a distance of 100 cm. During an 8-minute recording, patients were read a story of neutral interest to hold attention at a constant level. PAN was defined as a left-beating nystagmus, a transition phase, a right-beating nystagmus, and a final transition phase; the sequence was then repeated. RESULTS: Seven of the 18 patients had PAN (median cycle: 223 seconds, range 180-307 seconds). The periodicity of the cycles for each adult patient was regular, although the phases within a cycle were often asymmetric. Six of the seven patients had an anomalous head posture (AHP), and in five the AHP was in only one direction. Except for one patient, the PAN waveforms had an increasing slow-phase velocity in at least one phase of the cycle; in the other phase they were linear. CONCLUSIONS: The occurrence of PAN in CN is not as rare as previously thought and can be missed because of the long cycles and the use of only one AHP. The AHP was dependent on, and could be predicted from, the waveforms containing the longest foveation times. Although the waveforms and foveation times may differ among the phases of the PAN cycle, the periodicity of the cycle was usually regular and therefore predictable. Identification of PAN is essential in cases in which surgical treatment is considered for correction of AHPs.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
3/37. Spontaneous reversal of nystagmus in the dark.AIM: To report five children with horizontal jerk nystagmus in whom eye movement recordings in the dark revealed a spontaneous reversal in the direction of the nystagmus beat. Three patients were blind in one eye and were diagnosed as having a manifest latent nystagmus (MLN), and two patients had strabismus and congenital nystagmus (CN). methods: eye movements were recorded using DC electro-oculography with simultaneous video recording, including infrared recording in total darkness. RESULTS: Four patients had decelerating velocity slow phase jerk nystagmus when recorded under natural lighting conditions; the fifth case had accelerating velocity and linear slow phase jerk nystagmus. Under absolute darkness, nystagmus reversed in direction of beat with a mixture of linear and decelerating velocity slow phase waveforms. One child with unilateral anophthalmos could wilfully reverse the beat direction of his nystagmus by trying to look with his blind eye in the light and dark. CONCLUSIONS: These observations support the theory that LN/MLN beat direction is determined by the "presumed" viewing eye and may be consciously controlled. The spontaneous reversal of beat direction in the dark suggests eye dominance is predetermined. Eye movement recordings identified mixed nystagmus waveforms indicating that CN (accelerating velocity slow phases) and LN/MLN (linear/decelerating velocity slow phases) coexist in these subjects.- - - - - - - - - - ranking = 1.5keywords = near (Clic here for more details about this article) |
4/37. Dorsal midbrain syndrome secondary to a pineocytoma.BACKGROUND: Dorsal midbrain syndrome is a triad of signs consisting of vertical gaze palsy, light-near dissociation of the pupils, and convergence retraction nystagmus. Associated findings may also be present. The most-common etiologies are pineal gland tumors and midbrain infarction. pineal gland tumors are rare tumors that show a predilection for males. The specific tumor reported herein, a pineocytoma, shows no gender predilection and is most common in mid- to late adulthood. CASE REPORT: A 38-year-old Native American man came to us with signs and symptoms consistent with dorsal midbrain syndrome. A neurological evaluation revealed the presence of a pineocytoma, which was later excised unsuccessfully. An explanation of the findings associated with dorsal midbrain syndrome is provided. CONCLUSION: patients who demonstrate signs consistent with dorsal midbrain syndrome should be referred for a neurological evaluation--including an MRI--to rule out any midbrain lesion.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
5/37. Acquired pendular nystagmus with voluntary inhibition.This report documents a case of voluntary inhibition of acquired pendular nystagmus after head trauma. A 30-year-old male developed oscillopsia and decreased visual acuity, as well as findings of acquired pendular nystagmus with voluntary inhibition after head trauma. The EOG finding was horizontal 18-20 Hz bilateral symmetrical pendular nystagmus in all directions of gaze at near and distant fixation. Nystagmus did not change with 14 Prism Diopter base-out prisms on both eyes, but it was possible to abolish it intentionally. baclofen and clonazepam had no effect in improving the patient's symptoms and EOG finding.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
6/37. Maximal subtotal extirpation of the horizontal rectus extraocular muscles for the treatment of nystagmus with no null point. A report of four successful human cases.PURPOSE: To evaluate the visual and restoration of normal appearance results of maximal excision of the horizontal rectus muscles in nystagmus patients. SETTING: Menelik II Hospital, Addis Ababa, ethiopia and the Sinskey Eye Institute, Santa Monica, california. methods: The medial and lateral rectus muscles were extirpated as far back as possible with an enucleation snare in four patients with horizontal nystagmus. A complete eye examination was performed pre- and postoperatively. Using a camcorder, ocular movements were recorded before surgery, and at postop; days 1 and 40, and months 1, 3 and 10. RESULTS: All four patients had a marked reduction in both abnormal and normal horizontal eye movement, and improvement in objective visual acuity. Postoperative residual intermittent fine horizontal movement was recorded in the left eye in a 6 year old and in both eyes of a 41 year old patient. A residual rotary component was recorded in a 15 year-old patient. The 6 and 9 year-old patients each developed a moderate exotropia. The 15 and 41 year-old patients maintained binocular fusion with some residual ability to converge. Vision increased subjectively in all cases. CONCLUSION: Subtotal myectomy of the horizontal muscles in horizontal nystagmus with no null point was very effective in improving and/or eliminating horizontal eye movement. Restoration of normal or near normal appearance and improvement in visual acuity occurred in all cases. None of the patients complained of their loss of horizontal gaze and eye movement. More complete myectomy of the muscles should produce total elimination of both normal and abnormal horizontal eye movement including nystagmus.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
7/37. Bowtie and upbeat nystagmus evolving into hemi-seesaw nystagmus in medial medullary infarction: possible anatomic mechanisms.A 20-year-old man with bilateral medial medullary infarction showed transition of bowtie and upbeat nystagmus into hemi-seesaw nystagmus. Follow-up MRI revealed near complete resolution of the right medullary lesion. This transition of nystagmus suggests that the upbeat nystagmus was generated by bilateral lesions in the ascending pathways from both anterior semicircular canals (SCC), and that the hemi-seesaw nystagmus was caused by damage to the pathway from the left anterior SCC.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
8/37. arnold-chiari malformation.arnold-chiari malformation is a congenital malformation of the skull near the foramen magnum in which the cerebellum and the medulla are caudally displaced. This herniation of the brainstem causes down-beat nystagmus and oscillopsia, the most commonly presenting sign and symptom, respectively. Differential diagnoses for the arnold-chiari malformation include, but are not limited to, demyelinating disease, tumor, and vascular disorders. Symptoms will generally worsen with time and may even be brought on during exercise or valsalva maneuvers. A correct diagnosis can lead to timely surgical intervention which can improve the quality of eye movements. Treatment generally involves the surgical decompression of the surrounding spinal tissue.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
9/37. Transition from upbeat to downbeat nystagmus observed in a patient with Wernicke's encephalopathy.BACKGROUND: We report an unusual case of Wernicke's encephalopathy presenting with transient upbeat nystagmus that changed to a persistent downbeat nystagmus. CASE: A 27-year-old man presented with upbeat nystagmus. Three months earlier, he had been diagnosed with Wernicke's encephalopathy after fasting for a month. OBSERVATIONS: This diagnosis was supported by his symptoms (ataxia, a confused state). Clinical recovery followed thiamine therapy. His upbeat nystagmus had linear slow phases with average amplitude and frequency ( /-SD) during fixation straight ahead of 2.8 /- 0.7 degrees and 4.6 /- 2.2 Hz, respectively. Two months later, the primary position upbeat nystagmus had diminished and downbeat nystagmus (0.9 /- 0.5 degrees and 3.2 /- 0.7 Hz on average) for a 20 degrees downward gaze had developed. Then, 8 months later, he showed only downbeat nystagmus, which obeyed Alexander's law. His primary position downbeat nystagmus was completely suppressed by clonazepam, a gamma-aminobutyric acid (GABA) agonist. CONCLUSIONS: Owing to an underlying central vestibular imbalance, even after the recovery of acute neurological symptoms, Wernicke's encephalopathy can be complicated by persistent downbeat nystagmus, which can be treated by a GABA agonist.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
10/37. A newly recognised cause of vertigo: horizontal canal variant of benign positional vertigo.AIMS: To describe the presentation, causes, treatment, and outcomes of patients presenting with the newly recognised horizontal canal variant of benign positional vertigo (BPV); and to emphasise the importance of performing a positional test on all patients being assessed for vertigo. methods: The records on 400 patients presenting with BPV were analysed. Two detailed patient histories from 2004 are included. RESULTS: Forty-nine patients (12%) had horizontal canal BPV. The median presentation age was 59 years. In 17 patients, it presented de novo during repositioning treatment for 'classical' posterior canal BPV. Repositioning is in the horizontal plane, with the direction depending on whether the mechanism is canalithiasis or cupulolithiasis. CONCLUSIONS: Horizontal canal BPV explains nearly all variations on 'classical' (posterior canal) BPV. It accounts for at least 10% of BPV and has been frequently misdiagnosed. Repositioning is usually curative if the symptomatic ear is correctly identified.- - - - - - - - - - ranking = 0.5keywords = near (Clic here for more details about this article) |
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