Journal article
Muscimol inactivation caudal to the interstitial nucleus of Cajal induces hemi-seesaw nystagmus
Experimental brain research, Vol.205(3), pp.405-413
09/2010
DOI: 10.1007/s00221-010-2376-2
PMCID: PMC2965773
PMID: 20686890
Abstract
Hemi-seesaw nystagmus (hemi-SSN) is a jerk-waveform nystagmus with conjugate torsional and disjunctive vertical components. Halmagyi et al. in Brain 117(Pt 4):789-803 (1994), reported hemi-SSN in patients with unilateral lesions in the vicinity of the Interstitial Nucleus of Cajal (INC) and suggested that an imbalance in projections from the vestibular nuclei to the INC was the source of the nystagmus. However, this hypothesis was called into question by Helmchen et al. in Exp Brain Res 119(4):436-452 (1998), who inactivated INC in monkeys with muscimol (a GABA(A) agonist) and induced failure of vertical gaze-holding (neural integrator) function but not hemi-SSN. We injected 0.1-0.2 microl of 2% muscimol into the supraoculomotor area, 1-2 mm dorso-lateral to the right oculomotor nucleus and caudal to the right INC. A total of seven injections in two juvenile rhesus monkeys were performed. Hemi-SSN was noted within 5-10 min after injection for six of the injections. Around the time the hemi-SSN began, a small skew deviation also developed. However, there was no limitation of horizontal or vertical eye movements, suggesting that the nearby oculomotor nucleus was not initially compromised. Limitations in eye movement range developed about (1/2)-1 h following the injections. Clinical signs that were observed after the animal was released to his cage included a moderate to marked head tilt toward the left (contralesional) side, consistent with an ocular tilt reaction. We conclude that hemi-SSN can be caused by lesions just caudal to the INC, whereas lesions of the INC itself cause down-beat nystagmus and vertical gaze-holding failure, as demonstrated by Helmchen et al. Combined deficits may be encountered with lesions that involve several midbrain structures.
Details
- Title: Subtitle
- Muscimol inactivation caudal to the interstitial nucleus of Cajal induces hemi-seesaw nystagmus
- Creators
- Vallabh E Das - College of Optometry, University of Houston, Houston, TX 77204, USA. vdas@optometry.uh.eduR John LeighMichelle SwannMatthew J Thurtell
- Resource Type
- Journal article
- Publication Details
- Experimental brain research, Vol.205(3), pp.405-413
- Publisher
- Germany
- DOI
- 10.1007/s00221-010-2376-2
- PMID
- 20686890
- PMCID
- PMC2965773
- ISSN
- 0014-4819
- eISSN
- 1432-1106
- Grant note
- R01 EY006717-25 / NEI NIH HHS P51 RR000165 / NCRR NIH HHS R01-EY06717 / NEI NIH HHS P30 EY007551 / NEI NIH HHS R01 EY015312 / NEI NIH HHS RR00165 / NCRR NIH HHS P30 EY 07551 / NEI NIH HHS R01 EY015312-06 / NEI NIH HHS R01-EY015312 / NEI NIH HHS R01 EY006717 / NEI NIH HHS
- Language
- English
- Date published
- 09/2010
- Academic Unit
- Neurology; Ophthalmology and Visual Sciences
- Record Identifier
- 9983980077302771
Metrics
22 Record Views