N. Shameer Nijam
University hospitals of Leicester, UK
Biography:
Dr Nasrul Shameer Mohamadu Nijam.
Trainee in adult neurology.
Initial part of training in Sri Lanka – Teaching hospital of Kandy and national hospital of Sri Lanka, Colombo.
Currently following the compulsory overseas training in UK – University hospitals of Leicester.
Abstract:
Saccadic intrusions are involuntary conjugate saccades (fast eye movements) that interrupt fixation. Although, some of these may be seen in normal individuals, others are pathologic. they often reflect dysfunction of the brainstem, cerebellum, superior colliculus, basal ganglia, and/or cerebral hemispheres.
We may distinguish two groups of saccadic intrusions by the presence or absence of an intersaccadic interval.
Saccadic intrusions with intersaccadic intervals such as square wave jerks, macro saccadic oscillations and saccadic pulses may be seen in neurovegetative diseases and demyelinating diseases.
Saccadic intrusions without intersaccadic intervals such as ocular flutter and opsoclonus can be seen in various conditions. This includes para infectious brainstem encephalitis, metabolic toxic states, demyelinating diseases, inherited disorders and paraneoplastic conditions (primarily neuroblastoma in children, and small cell lung carcinoma, breast carcinoma or ovarian carcinoma in adults), although in many cases, the cause remains unknown.
Ocular flutter and opsoclonus are rarely caused by drugs and toxins. This association has been reported in drugs/toxins such as cocaine, phenytoin, lithium, amitriptyline, phencyclidine and more recently venlafaxine.
The pathophysiology of saccadic intrusions has been a matter of dispute encompassing several mechanisms which include brainstem and cerebellar theories.
The options for symptomatic management of saccadic intrusions are limited to some case reports.
Although rare, possibilities of drugs and toxins as the causative agents have to be considered early in the differential diagnoses.
There is a high chance of missing the complete diagnosis if the relevant investigations are delayed.