Video-electrooculographic Findings in Congenital Nystagmus Associated with Oculocutaneous Albinism
Malak Alaboudi1, Abdalmalik Bin Khunayfir1, Neel Fotedar1
1University Hospitals Cleveland Medical Center
Objective:
To report electro-oculographic (EOG) findings in congenital nystagmus in an adult patient with oculocutaneous albinism (OCA).
Background:
Pendular nystagmus is characterized by slow sinusoidal ocular oscillations whereas jerk nystagmus has a slow phase alternating with a fast phase. Congenital pendular nystagmus is most commonly seen in infantile nystagmus syndrome (INS), which in turn is associated with oculocutaneous albinism in ~25% of cases.1
Design/Methods:
We report video-EOG analysis of a 62-year old woman with OCA and nystagmus present since infancy. The EOG was recorded using the standard protocol developed at our institution.2 The human eye is an electrical dipole with the cornea being positive and the retina being negative. This allows for detection of direction and position of eye movements using EOG electrodes.2
Results:
On examination, the nystagmus was conjugate, horizontal and pendular in primary position and in vertical end-gaze. In horizontal end-gaze, the nystagmus had a jerky quality beating toward the direction of gaze. The nystagmus diminished with convergence.
Conclusions:
Nystagmus present since infancy is mainly classified into three syndromes- INS, fusional maldevelopment nystagmus syndrome and spasmus nutans.1 All three have some characteristic features. The characteristics reported in our case are most consistent with INS.
The nystagmus described in INS is mainly conjugate, horizontal and pendular in nature. The nystagmus can have jerky quality especially with end gaze where the slow phases have an increasing velocity waveform.1
Foveation periods are considered as characteristic of INS, although these can be rarely seen in acquired forms of pendular nystagmus.3-5 Foveation periods are hypothesized to explain the absence of oscillopsia in INS.1