Pendular Hemi–See-Saw Nystagmus With Oculopalatal Tremor: Case Report and Systematic Review
Fiorella Rivas Sarmiento1, Jesus Daniel Gutierrez Arratia1, Christoper A. Alarcon Ruiz2, Tony Torres Inuma1, Guido Alban Zapata1, Justiniano Zea Quispe3
1Instituto Nacional de Ciencias Neurologicas, 2Instituto Nacional de Ciencias Neurológicas, 3Perú
Objective:
To synthesize the evidence on HSSN and present a case with oculopalatal tremor (OPT)
Background:
Hemi–see-saw nystagmus (HSSN) is an uncommon subtype, characterized by elevation and intorsion of one eye with contralateral depression and extorsion, typically in a jerk pattern. It is associated with unilateral lesions of the interstitial nucleus of Cajal and the medial longitudinal fasciculus, structures involved in the ocular tilt reaction. Although its association with OPT has been described, it is rare
Design/Methods:
We performed a systematic review of seven databases on HSSN, extracting data on demographics, etiology, lesion location, oculomotor findings, nystagmus pattern, outcomes, and additionally present a representative case
Results:
A systematic review of seven databases identified 14 reports including 35 cases. Thirteen provided complete data, with a mean age of 42.1 ± 19.7 years (range 18–69) and 53.8% male. The main etiology was ischemic stroke (53.8%), followed by AVM, AOA2, Joubert syndrome, Chiari I malformation, and cavernous malformation (7.7%). Lesions most frequently involved the bulbar/medullary region (30.8%) and mesencephalic tegmentum (15.4%). Jerk nystagmus was predominant (97.1%), and internuclear ophthalmoplegia was the most common supranuclear abnormality (65.7%). Four patients had an ocular tilt reaction, and among five with outcome data, two achieved complete resolution. Only one case of pendular HSSN with OPT has been previously reported. We describe a 30-year-old man with a pontine AVM presenting with pendular HSSN, eight-and-a-half syndrome, gaze-evoked nystagmus, ocular tilt reaction, incomplete Horner syndrome, and palatal tremor, consistent with OPT
Conclusions:
HSSN is an uncommon nystagmus, most often vascular and with frequent lower brainstem involvement. While HSSN usually presents as jerk, co-occurrence with OPT can shift the waveform to pendular, likely reflecting maladaptive brainstem–cerebellar oscillatory mechanisms. Larger, anatomically precise series are needed to refine structure–function correlations and prognosis
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