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R A Yavor - One of the best experts on this subject based on the ideXlab platform.

  • sudden unilateral hearing loss with simultaneous ipsilateral Posterior Semicircular Canal benign paroxysmal positional vertigo a variant of vestibulo cochlear neurolabyrinthitis
    Archives of Otolaryngology-head & Neck Surgery, 2000
    Co-Authors: Mikael Karlberg, Michael G Halmagyi, Ulrich Buttner, R A Yavor
    Abstract:

    We describe 4 patients who all simultaneously developed a sudden total or partial unilateral sensorineural hearing loss and an unusual acute peripheral vestibulopathy in the same ear characterized by Posterior Semicircular Canal benign paroxysmal positional vertigo with intact lateral Semicircular Canal function. Two patients also had ipsilateral loss of otolith function. The vertigo resolved in all 4 patients after particle-repositioning maneuvers. The findings of audiometry and vestibular tests indicated that the lesion responsible for this syndrome was probably located within the labyrinth itself rather than within the vestibulocochlear nerve and that it was more likely a viral vestibulocochlear neurolabyrinthitis than a labyrinthine infarction.

  • Posterior Semicircular Canal nystagmus is conjugate and its axis is parallel to that of the Canal
    Neurology, 2000
    Co-Authors: Phillip D Cremer, D V Pohl, R A Yavor, Americo A Migliaccio, Ian S Curthoys, Leo Davies, G M Halmagyi
    Abstract:

    A patient with a postoperative fistula of the left Posterior Semicircular Canal is presented. Negative pressure in the external ear Canal produced upbeat-torsional nystagmus, which was recorded in three dimensions using binocular scleral search coils. The nystagmus was conjugate, without skew deviation, and its trajectory corresponded to the anatomic axis of the left Posterior Canal. The current study helps validate Ewald's first law in humans: the axis of nystagmus should match the anatomic axis of the Semicircular Canal that generated it. This law is clinically useful in diagnosing pathology of the vestibular end-organ, such as benign paroxysmal positional vertigo or the superior Semicircular Canal dehiscence syndrome.

  • Posterior Semicircular Canal nystagmus is conjugate and its axis is parallel to that of the Canal
    Neurology, 2000
    Co-Authors: Phillip D Cremer, R A Yavor, Americo A Migliaccio, David V Pohl, Ian S Curthoys, Leo Davies, G M Halmagyi
    Abstract:

    Article abstract A patient with a postoperative fistula of the left Posterior Semicircular Canal is presented. Negative pressure in the external ear Canal produced upbeat-torsional nystagmus, which was recorded in three dimensions using binocular scleral search coils. The nystagmus was conjugate, without skew deviation, and its trajectory corresponded to the anatomic axis of the left Posterior Canal. The current study helps validate Ewald’s first law in humans: the axis of nystagmus should match the anatomic axis of the Semicircular Canal that generated it. This law is clinically useful in diagnosing pathology of the vestibular end-organ, such as benign paroxysmal positional vertigo or the superior Semicircular Canal dehiscence syndrome.

  • The effect of unilateral Posterior Semicircular Canal inactivation on the human vestibulo-ocular reflex.
    Acta oto-laryngologica. Supplementum, 1995
    Co-Authors: G M Halmagyi, D V Pohl, I S Curthoys, R A Yavor, M J Todd
    Abstract:

    The responses to rapid, passive, unpredictable, low amplitude (10-20 degrees), high acceleration (3,000-4,000 degrees/s2) head rotations were used to study the human vestibulo-ocular reflex (VOR) in pitch and yaw plane after unilateral Posterior Semicircular Canal occlusion (uPCO) in 10 subjects. The results from these 10 uPCO subjects were compared with those from 18 normal subjects. The VOR gains at a head velocity of 200 degrees/s in the uPCO subjects were: pitch upward = 0.62 +/- 0.06, pitch downward = 0.87 +/- 0.11, yew ipsilesion = 0.78 +/- 0.06, yaw contralesion = 0.79 +/- 0.10 and in normal subjects were: pitch upward = 0.92 +/- 0.06, pitch downward = 0.96 +/- 0.04, yaw right = 0.88 +/- 0.05, yaw left = 0.91 +/- 0.12 (group means +/- twotailed 95% confidence intervals). The results showed that the pitch-vVOR gain was significantly (p < 0.05) decreased in response to upward head impulses whereas in response to downward, ipsilesion and contralesion head impulses were not significantly different (p > 0.05) from the normals. This study shows that there is 30% permanent residual deficit of the upward pitch-vVOR with an up-down asymmetry in pitch-vVOR gain following inactivation of a single Posterior Semicircular Canal and that compensation of pitch-vVOR function is incomplete.

  • The effect of unilateral Posterior Semicircular Canal inactivation on the human vestibulo-ocular reflex.
    Acta Oto-Laryngologica, 1995
    Co-Authors: G M Halmagyi, D V Pohl, R A Yavor, Ian S Curthoys, M J Todd
    Abstract:

    The responses to rapid, passive. unpredictable, low amplitude (10-20°), high acceleration (3,000-4,000°/s2) head rotations were used to study the human vestibulo-ocular reflex (VOR) in pitch and yaw plane after unilateral Posterior Semicircular Canal occlusion (uPCO) in 10 subjects. The results from these 10 uPCO subjects were compared with those from 18 normal subjects. The VOR gains at a head velocity of 200°/s in the uPCO subjects were: pitch upward = 0.62 ± 0.06, pitch downward = 0.87 ± 0.11, yaw ipsilesion = 0.78 ± 0.06, yaw contralesion = 0.79 ± 0.10 and in normal subjects were: pitch upward = 0.92 ± 0.06, pitch downward = 0.96 ± 0.04. yaw right = 0.88 ± 0.05, yaw left = 0.91 ± 0.12 (group means ± two-tailed 95% confidence intervals). The results showed that the pitch-vVOR gain was significantly (p 0.05) from the normals. This study sho...

G M Halmagyi - One of the best experts on this subject based on the ideXlab platform.

  • Posterior Semicircular Canal nystagmus is conjugate and its axis is parallel to that of the Canal
    Neurology, 2000
    Co-Authors: Phillip D Cremer, D V Pohl, R A Yavor, Americo A Migliaccio, Ian S Curthoys, Leo Davies, G M Halmagyi
    Abstract:

    A patient with a postoperative fistula of the left Posterior Semicircular Canal is presented. Negative pressure in the external ear Canal produced upbeat-torsional nystagmus, which was recorded in three dimensions using binocular scleral search coils. The nystagmus was conjugate, without skew deviation, and its trajectory corresponded to the anatomic axis of the left Posterior Canal. The current study helps validate Ewald's first law in humans: the axis of nystagmus should match the anatomic axis of the Semicircular Canal that generated it. This law is clinically useful in diagnosing pathology of the vestibular end-organ, such as benign paroxysmal positional vertigo or the superior Semicircular Canal dehiscence syndrome.

  • Posterior Semicircular Canal nystagmus is conjugate and its axis is parallel to that of the Canal
    Neurology, 2000
    Co-Authors: Phillip D Cremer, R A Yavor, Americo A Migliaccio, David V Pohl, Ian S Curthoys, Leo Davies, G M Halmagyi
    Abstract:

    Article abstract A patient with a postoperative fistula of the left Posterior Semicircular Canal is presented. Negative pressure in the external ear Canal produced upbeat-torsional nystagmus, which was recorded in three dimensions using binocular scleral search coils. The nystagmus was conjugate, without skew deviation, and its trajectory corresponded to the anatomic axis of the left Posterior Canal. The current study helps validate Ewald’s first law in humans: the axis of nystagmus should match the anatomic axis of the Semicircular Canal that generated it. This law is clinically useful in diagnosing pathology of the vestibular end-organ, such as benign paroxysmal positional vertigo or the superior Semicircular Canal dehiscence syndrome.

  • The effect of unilateral Posterior Semicircular Canal inactivation on the human vestibulo-ocular reflex.
    Acta oto-laryngologica. Supplementum, 1995
    Co-Authors: G M Halmagyi, D V Pohl, I S Curthoys, R A Yavor, M J Todd
    Abstract:

    The responses to rapid, passive, unpredictable, low amplitude (10-20 degrees), high acceleration (3,000-4,000 degrees/s2) head rotations were used to study the human vestibulo-ocular reflex (VOR) in pitch and yaw plane after unilateral Posterior Semicircular Canal occlusion (uPCO) in 10 subjects. The results from these 10 uPCO subjects were compared with those from 18 normal subjects. The VOR gains at a head velocity of 200 degrees/s in the uPCO subjects were: pitch upward = 0.62 +/- 0.06, pitch downward = 0.87 +/- 0.11, yew ipsilesion = 0.78 +/- 0.06, yaw contralesion = 0.79 +/- 0.10 and in normal subjects were: pitch upward = 0.92 +/- 0.06, pitch downward = 0.96 +/- 0.04, yaw right = 0.88 +/- 0.05, yaw left = 0.91 +/- 0.12 (group means +/- twotailed 95% confidence intervals). The results showed that the pitch-vVOR gain was significantly (p < 0.05) decreased in response to upward head impulses whereas in response to downward, ipsilesion and contralesion head impulses were not significantly different (p > 0.05) from the normals. This study shows that there is 30% permanent residual deficit of the upward pitch-vVOR with an up-down asymmetry in pitch-vVOR gain following inactivation of a single Posterior Semicircular Canal and that compensation of pitch-vVOR function is incomplete.

  • The effect of unilateral Posterior Semicircular Canal inactivation on the human vestibulo-ocular reflex.
    Acta Oto-Laryngologica, 1995
    Co-Authors: G M Halmagyi, D V Pohl, R A Yavor, Ian S Curthoys, M J Todd
    Abstract:

    The responses to rapid, passive. unpredictable, low amplitude (10-20°), high acceleration (3,000-4,000°/s2) head rotations were used to study the human vestibulo-ocular reflex (VOR) in pitch and yaw plane after unilateral Posterior Semicircular Canal occlusion (uPCO) in 10 subjects. The results from these 10 uPCO subjects were compared with those from 18 normal subjects. The VOR gains at a head velocity of 200°/s in the uPCO subjects were: pitch upward = 0.62 ± 0.06, pitch downward = 0.87 ± 0.11, yaw ipsilesion = 0.78 ± 0.06, yaw contralesion = 0.79 ± 0.10 and in normal subjects were: pitch upward = 0.92 ± 0.06, pitch downward = 0.96 ± 0.04. yaw right = 0.88 ± 0.05, yaw left = 0.91 ± 0.12 (group means ± two-tailed 95% confidence intervals). The results showed that the pitch-vVOR gain was significantly (p 0.05) from the normals. This study sho...

Yoshio Uchino - One of the best experts on this subject based on the ideXlab platform.

  • Properties and axonal trajectories of Posterior Semicircular Canal nerve-activated vestibulospinal neurons
    Experimental Brain Research, 2008
    Co-Authors: Keisuke Kushiro, Naoharu Kitajima, Akemi Sugita-kitajima, Yoshio Uchino
    Abstract:

    We studied the axonal projections of vestibulospinal neurons activated from the Posterior Semicircular Canal. The axonal projection level, axonal pathway, and location of the vestibulospinal neurons originating from the PC were investigated in seven decerebrated cats. Selective electrical stimulation was applied to the PC nerve, and extracellular recordings in the vestibular nuclei were performed. The properties of the PC nerve-activated vestibulospinal neurons were then studied. To estimate the neural pathway in the spinal cord, floating electrodes were placed at the ipsilateral (i) and contralateral (c) lateral vestibulospinal tract (LVST) and medial vestibulospinal tract (MVST) at the C1/C2 junction. To elucidate the projection level, floating electrodes were placed at i-LVST and MVST at the C3, T1, and L3 segments in the spinal cord. Collision block test between orthodromic inputs from the PC nerve and antidromic inputs from the spinal cord verified the existence of the vestibulospinal neurons in the vestibular nuclei. Most (44/47) of the PC nerve-activated vestibulospinal neurons responded to orthodromic stimulation to the PC nerve with a short (

  • Axonal Pathways and Projection Levels of Vestibulospinal Neurons Activated by Posterior Semicircular Canal
    Equilibrium Research, 2000
    Co-Authors: Akira Hagiwara, Yoshio Uchino, H. Sato, H. Meng, Mamoru Suzuki
    Abstract:

    Axonal pathways and the projection levels of Posterior-Semicircular Canal (PC)-ac-tivated vestibulospinal neurons were studied in decerebrated and anesthetized cats. The PC nerve was selectively stimulated by bipolar silver electrodes. Two monopolar electrodes were inserted into the lateral vestibulospinal tract (LVST) and medial vestibulospinal tract (MVST) to determine the pathway of axons. Three pairs of similar electrodes were positioned in the C2-3, C7-T1 and T12-L3 segments to examine projection levels. Another monopolar electrode was placed in the oculomotor nuclei to determine whether PC-nerve-activated vestibulospinal neurons s have branches ascending to the oculomotor nuclei.Fifty six neurons were activated orthodromically after PC nerve stimulation. Ten PC-nerve-activated vestibulospinal neurons were also antidromicaly activated from the oculomotor nuclei. All of these vestibulo-oculo-spinal (VOS) neurons descended through the MVST and terminated in the upper cervical segments. Eighteen PC-ner-ve-activated vestibulospinal neurons descended through the LVST, 45% of which reached upper lumber segments. Fourteen vestibulospinal neurons descended through the MVST. Most of these terminated in upper cervical segments. These results suggest that VOS neurons convey Posterior Semicircular Canal signals to both the ocular and neck motor centers, linking eye and head movement.

Glenn W Knox - One of the best experts on this subject based on the ideXlab platform.

  • CO2 laser-assisted Posterior Semicircular Canal ablation for benign paroxysmal positional vertigo.
    The Laryngoscope, 2010
    Co-Authors: Glenn W Knox
    Abstract:

    The objective of this study was to analyze a new technique, CO2 laser-assisted Posterior Semicircular Canal ablation (LAPSCCA), in the treatment of refractory benign paroxysmal positional vertigo. Prospective study of patients with disabling BPPV who failed conservative therapy. Patients noted to have been treated with at least three Epley maneuvers without success and continuing to have disabling symptoms were enrolled in this study. Patients underwent pre- and post-operative electronystagmography. The surgical technique is modified from Parnes1 and involves plugging each end of the fenestrated Posterior Semicircular Canal with bone grafts and fibrin glue. The CO2 fiberoptic (Omniguide) laser is then used at a setting of 2 watts to incise between the cut ends of the Canal to completely section the membranous labyrinth. All six patients had excellent relief of positional vertigo symptoms. LAPSCCA is an excellent treatment option for patients with intractable BPPV.

  • CO2 Laser‐Assisted Posterior Semicircular Canal Ablation for Benign Paroxysmal Positional Vertigo
    The Laryngoscope, 2010
    Co-Authors: Glenn W Knox
    Abstract:

    OBJECTIVES: The objective of this study was to analyze a new technique, CO2 laser-assisted Posterior Semicircular Canal ablation (LAPSCCA), in the treatment of refractory benign paroxysmal positional vertigo. STUDY DESIGN: Prospective study of patients with disabling BPPV who failed conservative therapy. METHODS: Patients noted to have been treated with at least three Epley maneuvers without success and continuing to have disabling symptoms were enrolled in this study. Patients underwent pre- and post-operative electronystagmography. The surgical technique is modified from Parnes1 and involves plugging each end of the fenestrated Posterior Semicircular Canal with bone grafts and fibrin glue. The CO2 fiberoptic (Omniguide) laser is then used at a setting of 2 watts to incise between the cut ends of the Canal to completely section the membranous labyrinth. RESULTS: All six patients had excellent relief of positional vertigo symptoms. CONCLUSIONS: LAPSCCA is an excellent treatment option for patients with intractable BPPV.

  • co2 laser assisted Posterior Semicircular Canal ablation for benign paroxysmal positional vertigo
    Laryngoscope, 2010
    Co-Authors: Glenn W Knox
    Abstract:

    OBJECTIVES: The objective of this study was to analyze a new technique, CO2 laser-assisted Posterior Semicircular Canal ablation (LAPSCCA), in the treatment of refractory benign paroxysmal positional vertigo. STUDY DESIGN: Prospective study of patients with disabling BPPV who failed conservative therapy. METHODS: Patients noted to have been treated with at least three Epley maneuvers without success and continuing to have disabling symptoms were enrolled in this study. Patients underwent pre- and post-operative electronystagmography. The surgical technique is modified from Parnes1 and involves plugging each end of the fenestrated Posterior Semicircular Canal with bone grafts and fibrin glue. The CO2 fiberoptic (Omniguide) laser is then used at a setting of 2 watts to incise between the cut ends of the Canal to completely section the membranous labyrinth. RESULTS: All six patients had excellent relief of positional vertigo symptoms. CONCLUSIONS: LAPSCCA is an excellent treatment option for patients with intractable BPPV.

Ian S Curthoys - One of the best experts on this subject based on the ideXlab platform.

  • Posterior Semicircular Canal nystagmus is conjugate and its axis is parallel to that of the Canal
    Neurology, 2000
    Co-Authors: Phillip D Cremer, R A Yavor, Americo A Migliaccio, David V Pohl, Ian S Curthoys, Leo Davies, G M Halmagyi
    Abstract:

    Article abstract A patient with a postoperative fistula of the left Posterior Semicircular Canal is presented. Negative pressure in the external ear Canal produced upbeat-torsional nystagmus, which was recorded in three dimensions using binocular scleral search coils. The nystagmus was conjugate, without skew deviation, and its trajectory corresponded to the anatomic axis of the left Posterior Canal. The current study helps validate Ewald’s first law in humans: the axis of nystagmus should match the anatomic axis of the Semicircular Canal that generated it. This law is clinically useful in diagnosing pathology of the vestibular end-organ, such as benign paroxysmal positional vertigo or the superior Semicircular Canal dehiscence syndrome.

  • Posterior Semicircular Canal nystagmus is conjugate and its axis is parallel to that of the Canal
    Neurology, 2000
    Co-Authors: Phillip D Cremer, D V Pohl, R A Yavor, Americo A Migliaccio, Ian S Curthoys, Leo Davies, G M Halmagyi
    Abstract:

    A patient with a postoperative fistula of the left Posterior Semicircular Canal is presented. Negative pressure in the external ear Canal produced upbeat-torsional nystagmus, which was recorded in three dimensions using binocular scleral search coils. The nystagmus was conjugate, without skew deviation, and its trajectory corresponded to the anatomic axis of the left Posterior Canal. The current study helps validate Ewald's first law in humans: the axis of nystagmus should match the anatomic axis of the Semicircular Canal that generated it. This law is clinically useful in diagnosing pathology of the vestibular end-organ, such as benign paroxysmal positional vertigo or the superior Semicircular Canal dehiscence syndrome.

  • The effect of unilateral Posterior Semicircular Canal inactivation on the human vestibulo-ocular reflex.
    Acta Oto-Laryngologica, 1995
    Co-Authors: G M Halmagyi, D V Pohl, R A Yavor, Ian S Curthoys, M J Todd
    Abstract:

    The responses to rapid, passive. unpredictable, low amplitude (10-20°), high acceleration (3,000-4,000°/s2) head rotations were used to study the human vestibulo-ocular reflex (VOR) in pitch and yaw plane after unilateral Posterior Semicircular Canal occlusion (uPCO) in 10 subjects. The results from these 10 uPCO subjects were compared with those from 18 normal subjects. The VOR gains at a head velocity of 200°/s in the uPCO subjects were: pitch upward = 0.62 ± 0.06, pitch downward = 0.87 ± 0.11, yaw ipsilesion = 0.78 ± 0.06, yaw contralesion = 0.79 ± 0.10 and in normal subjects were: pitch upward = 0.92 ± 0.06, pitch downward = 0.96 ± 0.04. yaw right = 0.88 ± 0.05, yaw left = 0.91 ± 0.12 (group means ± two-tailed 95% confidence intervals). The results showed that the pitch-vVOR gain was significantly (p 0.05) from the normals. This study sho...