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Co-occurrence of periodic alternating and pendular seesaw nystagmus in blindness
Journal of the Neurological Sciences 285 (2009) 257–258
Contents lists available at ScienceDirect
Journal of the Neurological Sciences j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / j n s
Short communication
Co-occurrence of periodic alternating and pendular seesaw nystagmus in blindness☆ Seong-Hae Jeong a,c, Jeong-Min Hwang b, Ji Soo Kim a,⁎ a b c
Department of Neurology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea Department of Neurology, Chungnam National University Hospital, Republic of Korea
a r t i c l e
i n f o
Article history: Received 15 February 2009 Received in revised form 14 May 2009 Accepted 16 June 2009 Available online 16 July 2009 Keywords: Blindness Seesaw nystagmus Periodic alternating nystagmus Skew Torsion
a b s t r a c t Even though pendular seesaw nystagmus (PSN) or periodic alternating nystagmus (PAN) has been reported in blind persons, the co-occurrence of PSN and PAN has not been described. A 69-year-old woman with progressive visual loss to only light perception in both eyes showed PSN with a conjugate torsional component and the vertical components in the opposite directions in both eyes. In complete darkness, she also exhibited PAN in addition to PSN. PSN remained unchanged in darkness. The rest of the neurological examination, testing for mitochondrial mutations of Leber's hereditary optic neuropathy, fluorescent angiography, electroretinogram, and brain MRI were normal except for bilateral optic atrophy. Deprivation of the visual inputs, which are required to calibrate normal eye motion, may produce various ocular motor abnormalities in blindness. Although the co-occurrence of PSN and PAN in our patient with visual loss indicates a common etiology, the different effects of darkness on nystagmus intensity suggest a distinct pathomechanism. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Blind persons may show involuntary eye movements including pendular seesaw nystagmus (PSN), ocular roving and periodic alternating nystagmus (PAN) [1]. PSN is a slow and smooth eye oscillation characterized by alternating vertical skew deviation and conjugate ocular torsion [2] while PAN refers to periodic reversal of horizontal jerk nystagmus with a null period of several seconds [1]. Even though PSN [2] or PAN [3] has been reported in blind patients, the co-occurrence of PSN and PAN has not been described in a patient with visual loss.
2. Case report A 69-year-old woman was referred for evaluation of involuntary eye movements associated with progressive visual loss. Her past medical history included a surgical resection of pituitary adenoma 13 years before, which had been detected initially during evaluation of visual disturbance in another hospital. However, findings of the
☆ This study was supported by a grant of the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (A080750). ⁎ Corresponding author. Department of Neurology, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-707, Republic of Korea. Tel.: + 82 31 787 7463; fax: + 82 31 719 6828. E-mail address: [email protected] (J.S. Kim). 0022-510X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2009.06.042
neuro-ophthalmologic examination at that time were unavailable. Five years later, the patient's visual acuity measured 20/40 OD and 20/20 OS, and further deteriorated to detection of hand movements at 20 cm OD and 20/200 OS on follow-up examination 3 years later. The patient had been taking aspirin and oral hypoglycemic agents due to diabetes mellitus. She also reported a whiplash injury without loss of consciousness or cerebral lesions 5 years before the present examination. However, she denied any exposure to toxins or nutritional problems. Her family history was unremarkable. The present examination revealed binocular visual acuities restricted to light perception. Pupillary light reflexes were decreased bilaterally without a relative afferent pupillary defect. Intraocular pressure was normal in both eyes. Fundoscopic examination disclosed bilateral optic disc atrophy without diabetic retinopathy (Fig. 1A). The patient also showed pendular oscillation of the eyes with a conjugate torsional component and the vertical components in the opposite directions in both eyes, which is termed PSN (Video 1) [4]. Video-oculographic recording of eye motion in complete darkness showed an emergence of PAN (0.1–4.5°) in addition to the PSN (1.7–5°, Fig. 1B, Video 2). The right beating component of PAN was longer (duration = 30–120 s) than the left beating one (duration = 20–50 s, Fig. 1C). The PSN remained unchanged in darkness. There was no head tilt or periodic head turn. The patient did not perceive the involuntary eye movements. Ocular motor ranges were full, but saccades and smooth pursuit were poorly performed, most likely due to the visual loss and involuntary eye movements. The rest of the neurological examination was normal. Routine blood chemistry and thyroid function tests were unrevealing. Mitochondrial mutations for Leber's hereditary optic neuropathy
258
S.-H. Jeong et al. / Journal of the Neurological Sciences 285 (2009) 257–258
Fig. 1. A. Fundus photography shows pale and atrophic optic discs bilaterally. B. Video-oculographic recording of eye motion in complete darkness shows periodic alternating nystagmus (PAN) in addition to pendular seesaw nystagmus (PSN). Upward deflection indicates rightward, upward and clockwise eye motion. C. Temporal profile of the slow-phase velocity (SPV) of the periodic alternating nystagmus consists of left beating nystagmus, a transition phase, and right beating nystagmus. RH: horizontal position of right eye. LH: horizontal position of left eye. RV: vertical position of right eye. LV: vertical position of left eye. RT: torsional position of right eye. LT: torsional position of left eye.
(LHON) were not found at nucleotides 11778, 14484, 3460, and 15257. Results of fluorescent angiography, electroretinogram and brain MRI were also normal. 3. Discussion We observed PSN and PAN in a woman with visual loss due to bilateral optic atrophy. Both forms of nystagmus may be regarded as the consequences of deprivation of visual inputs, which are essential for normal calibration of eye movements [1]. PSN has mostly been reported in patients with large tumors in the region of the optic chiasm and thus has been attributed to the effects of chiasmal visual field defects [1]. Since parasellar lesions especially affect the temporal visual fields, loss of the crossed inputs from the nasal retina seems to affect the gaze stability in the frontal plane; leading to seesaw nystagmus [1]. Even though our patient had a history of pituitary adenoma, the PSN appears to be unrelated with the tumor itself in view of the long interval from the surgery to the onset of visual loss and no evidence of tumor recurrence on follow-up image. Furthermore, development of PSN in patients with visual loss without a structural lesion [2] supports the hypothesis that PSN may be caused by visual impairment itself. Loss of visual inputs to the nodulus/uvula causes instability of the velocity storage mechanism that prolongs vestibular signals from the labyrinth; adaptive mechanisms then lead to the oscillations of PAN [1,5,6]. Either PSN or PAN has previously been reported in blind patients, but not together. A notable finding is that, even in the patient whose vision reduced to light perception, complete darkness was necessary for PAN to develop while PSN occurred either in light or darkness. The relationship of PAN with darkness is of interest. While reported cases of congenital PAN showed an increase of amplitude with visual fixation [6], acquired PAN concomitant with visual loss usually emerges or increases in darkness, as was in our patient [5]. Clearance of PAN with a restoration of vision also supports the importance of visual function in relation to PAN [5]. In contrast, a previous report described PSN only in light in a patient with visual loss (visual acuity of hand motion at 0.6 m in each eye) [2]. Furthermore, fixation increased or decreased the PSN associated with bitemporal hemianopsia due to suprasellar tumors [7]. Even though PSN and PAN were associated with visual loss in our patient, the effects of darkness on these nystagmus were different; PAN emerged only in darkness
while PSN remained unchanged. Although the co-occurrence of PSN and PAN in a patient with visual loss indicates a common etiology [8], the different effects of darkness on nystagmus intensity suggest a distinct pathomechanism. The various mechanisms of involuntary eye movements in blindness remain to be elucidated. A group of blind patients due to the diseases affecting the anterior visual pathway showed an inability to maintain steady eye position, resulting in jerk nystagmus [9]. Furthermore, voluntary saccadic initiation, self-tracking smooth pursuit and vestibular ocular reflex were more severely impaired in patients with early loss of visual function [9]. Deprivation of the visual inputs, which are required to calibrate normal eye motion, may produce various ocular motor abnormalities [9]. The etiology of progressive bilateral visual loss was unknown in our patient, partly due to the long interval from the onset of visual loss to the present examination and absence of a thorough neuroophthalmological evaluation during the course of visual loss. Therefore, it cannot be excluded that the cause of progressive visual loss might have been related to the generation of PSN and PAN. Appendix A. Supplementary data Supplementary data associated with this article can be found, in online version, at doi:10.1016/j.jns.2009.06.042. References [1] Leigh RJ, Zee DS. The neurology of eye movements. 4th ed. New York: Oxford Univ Press; 2006. p. 496–508. [2] May EF, Truxal AR. Loss of vision alone may result in seesaw nystagmus. J Neuroophthalmol 1997;17:84–5. [3] David DG, Smith JL. Periodic alternating nystagmus. A report of eight cases. Am J Ophthalmol 1971;72:757–62. [4] Maddox EE. See-saw nystagmus with bitemporal hemianopsia. Proc R Soc Med 1914;7:12–3. [5] Cross SA, Smith JL, Norton EW. Periodic alternating nystagmus clearing after vitrectomy. J Clin Neuro-ophthalmol 1982;2:5–11. [6] Baloh RW, Honrubia V, Konrad HR. Periodic alternating nystagmus. Brain 1976;99:11–26. [7] Arnott EJ. Vertical see-saw nystagmus. Trans Ophthalmol Soc U K 1964;84:251–7. [8] Hall EC, Gordon J, Abel LA, Hainline L, Abramov I. Nystagmus waveforms in blindness. Vis Impair Res 2000;12:65–73. [9] Leigh RJ, Zee DS. Eye movements of the blind. Invest Ophthalmol Vis Sci 1980;19:328–31.
Contents lists available at ScienceDirect
Journal of the Neurological Sciences j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / j n s
Short communication
Co-occurrence of periodic alternating and pendular seesaw nystagmus in blindness☆ Seong-Hae Jeong a,c, Jeong-Min Hwang b, Ji Soo Kim a,⁎ a b c
Department of Neurology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Republic of Korea Department of Neurology, Chungnam National University Hospital, Republic of Korea
a r t i c l e
i n f o
Article history: Received 15 February 2009 Received in revised form 14 May 2009 Accepted 16 June 2009 Available online 16 July 2009 Keywords: Blindness Seesaw nystagmus Periodic alternating nystagmus Skew Torsion
a b s t r a c t Even though pendular seesaw nystagmus (PSN) or periodic alternating nystagmus (PAN) has been reported in blind persons, the co-occurrence of PSN and PAN has not been described. A 69-year-old woman with progressive visual loss to only light perception in both eyes showed PSN with a conjugate torsional component and the vertical components in the opposite directions in both eyes. In complete darkness, she also exhibited PAN in addition to PSN. PSN remained unchanged in darkness. The rest of the neurological examination, testing for mitochondrial mutations of Leber's hereditary optic neuropathy, fluorescent angiography, electroretinogram, and brain MRI were normal except for bilateral optic atrophy. Deprivation of the visual inputs, which are required to calibrate normal eye motion, may produce various ocular motor abnormalities in blindness. Although the co-occurrence of PSN and PAN in our patient with visual loss indicates a common etiology, the different effects of darkness on nystagmus intensity suggest a distinct pathomechanism. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Blind persons may show involuntary eye movements including pendular seesaw nystagmus (PSN), ocular roving and periodic alternating nystagmus (PAN) [1]. PSN is a slow and smooth eye oscillation characterized by alternating vertical skew deviation and conjugate ocular torsion [2] while PAN refers to periodic reversal of horizontal jerk nystagmus with a null period of several seconds [1]. Even though PSN [2] or PAN [3] has been reported in blind patients, the co-occurrence of PSN and PAN has not been described in a patient with visual loss.
2. Case report A 69-year-old woman was referred for evaluation of involuntary eye movements associated with progressive visual loss. Her past medical history included a surgical resection of pituitary adenoma 13 years before, which had been detected initially during evaluation of visual disturbance in another hospital. However, findings of the
☆ This study was supported by a grant of the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (A080750). ⁎ Corresponding author. Department of Neurology, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-707, Republic of Korea. Tel.: + 82 31 787 7463; fax: + 82 31 719 6828. E-mail address: [email protected] (J.S. Kim). 0022-510X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2009.06.042
neuro-ophthalmologic examination at that time were unavailable. Five years later, the patient's visual acuity measured 20/40 OD and 20/20 OS, and further deteriorated to detection of hand movements at 20 cm OD and 20/200 OS on follow-up examination 3 years later. The patient had been taking aspirin and oral hypoglycemic agents due to diabetes mellitus. She also reported a whiplash injury without loss of consciousness or cerebral lesions 5 years before the present examination. However, she denied any exposure to toxins or nutritional problems. Her family history was unremarkable. The present examination revealed binocular visual acuities restricted to light perception. Pupillary light reflexes were decreased bilaterally without a relative afferent pupillary defect. Intraocular pressure was normal in both eyes. Fundoscopic examination disclosed bilateral optic disc atrophy without diabetic retinopathy (Fig. 1A). The patient also showed pendular oscillation of the eyes with a conjugate torsional component and the vertical components in the opposite directions in both eyes, which is termed PSN (Video 1) [4]. Video-oculographic recording of eye motion in complete darkness showed an emergence of PAN (0.1–4.5°) in addition to the PSN (1.7–5°, Fig. 1B, Video 2). The right beating component of PAN was longer (duration = 30–120 s) than the left beating one (duration = 20–50 s, Fig. 1C). The PSN remained unchanged in darkness. There was no head tilt or periodic head turn. The patient did not perceive the involuntary eye movements. Ocular motor ranges were full, but saccades and smooth pursuit were poorly performed, most likely due to the visual loss and involuntary eye movements. The rest of the neurological examination was normal. Routine blood chemistry and thyroid function tests were unrevealing. Mitochondrial mutations for Leber's hereditary optic neuropathy
258
S.-H. Jeong et al. / Journal of the Neurological Sciences 285 (2009) 257–258
Fig. 1. A. Fundus photography shows pale and atrophic optic discs bilaterally. B. Video-oculographic recording of eye motion in complete darkness shows periodic alternating nystagmus (PAN) in addition to pendular seesaw nystagmus (PSN). Upward deflection indicates rightward, upward and clockwise eye motion. C. Temporal profile of the slow-phase velocity (SPV) of the periodic alternating nystagmus consists of left beating nystagmus, a transition phase, and right beating nystagmus. RH: horizontal position of right eye. LH: horizontal position of left eye. RV: vertical position of right eye. LV: vertical position of left eye. RT: torsional position of right eye. LT: torsional position of left eye.
(LHON) were not found at nucleotides 11778, 14484, 3460, and 15257. Results of fluorescent angiography, electroretinogram and brain MRI were also normal. 3. Discussion We observed PSN and PAN in a woman with visual loss due to bilateral optic atrophy. Both forms of nystagmus may be regarded as the consequences of deprivation of visual inputs, which are essential for normal calibration of eye movements [1]. PSN has mostly been reported in patients with large tumors in the region of the optic chiasm and thus has been attributed to the effects of chiasmal visual field defects [1]. Since parasellar lesions especially affect the temporal visual fields, loss of the crossed inputs from the nasal retina seems to affect the gaze stability in the frontal plane; leading to seesaw nystagmus [1]. Even though our patient had a history of pituitary adenoma, the PSN appears to be unrelated with the tumor itself in view of the long interval from the surgery to the onset of visual loss and no evidence of tumor recurrence on follow-up image. Furthermore, development of PSN in patients with visual loss without a structural lesion [2] supports the hypothesis that PSN may be caused by visual impairment itself. Loss of visual inputs to the nodulus/uvula causes instability of the velocity storage mechanism that prolongs vestibular signals from the labyrinth; adaptive mechanisms then lead to the oscillations of PAN [1,5,6]. Either PSN or PAN has previously been reported in blind patients, but not together. A notable finding is that, even in the patient whose vision reduced to light perception, complete darkness was necessary for PAN to develop while PSN occurred either in light or darkness. The relationship of PAN with darkness is of interest. While reported cases of congenital PAN showed an increase of amplitude with visual fixation [6], acquired PAN concomitant with visual loss usually emerges or increases in darkness, as was in our patient [5]. Clearance of PAN with a restoration of vision also supports the importance of visual function in relation to PAN [5]. In contrast, a previous report described PSN only in light in a patient with visual loss (visual acuity of hand motion at 0.6 m in each eye) [2]. Furthermore, fixation increased or decreased the PSN associated with bitemporal hemianopsia due to suprasellar tumors [7]. Even though PSN and PAN were associated with visual loss in our patient, the effects of darkness on these nystagmus were different; PAN emerged only in darkness
while PSN remained unchanged. Although the co-occurrence of PSN and PAN in a patient with visual loss indicates a common etiology [8], the different effects of darkness on nystagmus intensity suggest a distinct pathomechanism. The various mechanisms of involuntary eye movements in blindness remain to be elucidated. A group of blind patients due to the diseases affecting the anterior visual pathway showed an inability to maintain steady eye position, resulting in jerk nystagmus [9]. Furthermore, voluntary saccadic initiation, self-tracking smooth pursuit and vestibular ocular reflex were more severely impaired in patients with early loss of visual function [9]. Deprivation of the visual inputs, which are required to calibrate normal eye motion, may produce various ocular motor abnormalities [9]. The etiology of progressive bilateral visual loss was unknown in our patient, partly due to the long interval from the onset of visual loss to the present examination and absence of a thorough neuroophthalmological evaluation during the course of visual loss. Therefore, it cannot be excluded that the cause of progressive visual loss might have been related to the generation of PSN and PAN. Appendix A. Supplementary data Supplementary data associated with this article can be found, in online version, at doi:10.1016/j.jns.2009.06.042. References [1] Leigh RJ, Zee DS. The neurology of eye movements. 4th ed. New York: Oxford Univ Press; 2006. p. 496–508. [2] May EF, Truxal AR. Loss of vision alone may result in seesaw nystagmus. J Neuroophthalmol 1997;17:84–5. [3] David DG, Smith JL. Periodic alternating nystagmus. A report of eight cases. Am J Ophthalmol 1971;72:757–62. [4] Maddox EE. See-saw nystagmus with bitemporal hemianopsia. Proc R Soc Med 1914;7:12–3. [5] Cross SA, Smith JL, Norton EW. Periodic alternating nystagmus clearing after vitrectomy. J Clin Neuro-ophthalmol 1982;2:5–11. [6] Baloh RW, Honrubia V, Konrad HR. Periodic alternating nystagmus. Brain 1976;99:11–26. [7] Arnott EJ. Vertical see-saw nystagmus. Trans Ophthalmol Soc U K 1964;84:251–7. [8] Hall EC, Gordon J, Abel LA, Hainline L, Abramov I. Nystagmus waveforms in blindness. Vis Impair Res 2000;12:65–73. [9] Leigh RJ, Zee DS. Eye movements of the blind. Invest Ophthalmol Vis Sci 1980;19:328–31.