1. Conclusions ■ Convergence spasm is: − Difficult to observe and easy to misinterpret − Often an expression of functional disease − Often the stimulus for expensive/ invasive/ unhelpful investigations ■ Infrared video goggles allow: − Observation of eye movements under controlled conditions − Video play-back (detailed analysis/ 2 nd opinion/ patient education) ■ Technique not previously used for this purpose ■ These case reports demonstrate potential for this diagnostic technique Conclusions ■ Convergence spasm is: − Difficult to observe and easy to misinterpret − Often an expression of functional disease − Often the stimulus for expensive/ invasive/ unhelpful investigations ■ Infrared video goggles allow: − Observation of eye movements under controlled conditions − Video play-back (detailed analysis/ 2 nd opinion/ patient education) ■ Technique not previously used for this purpose ■ These case reports demonstrate potential for this diagnostic technique Convergence Spasm Infrared video goggles: a novel diagnostic tool Newby RE, Lewis M Department of Neurology, Pinderfields Hospital, Wakefield Abstract Convergence spasm is defined by a triad of clinical signs: intermittent sustained convergence, accommodative spasm and miosis. To the unwary examiner this can mimic a range of ophthalmoplegic syndromes, most commonly abducens palsy or myasthenia gravis. Whilst it can be associated with organic disease (in brainstem and diencephalic lesions or metabolic encephalopathies), more often it is an expression of functional disease. Thus accurate diagnosis of this disorder may obviate the necessity for expensive and inappropriate investigations. Crucial to diagnosis is observation of pupillary constriction on attempted eye abduction. This can be difficult to appreciate under normal circumstances when pupillary constriction to light can complicate the clinical picture. We would like to present three cases of convergence spasm for which diagnosis was confirmed using a novel diagnostic tool: infrared video goggles. These goggles, usually utilised in nystagmography, permit close-up recordings of eye movements, which may be played back to allow more accurate analysis. The infrared recording technique permits examination in low light conditions, thus removing the potentially misleading pupillary response to light. We suggest that the use of this technique will allow confident diagnosis of convergence spasm to be made earlier, thus avoiding unnecessary investigations and permitting earlier treatment. Infrared Video Goggles ■ Conventionally used for nystagmography ■ One ‘lens’ obscured and connected to an infrared video recorder ■ Play-back allows detailed analysis ■ Observation in low light conditions limits impact of confounders − Visual fixation (nystagmus) − Light reflex (convergence spasm) Figure 1: Infrared video goggles in use with infrared image displayed on the screen Case One ■ 46 year old male ■ Past history: ‘TIAs’, cluster headache & gastric bypass ■ Presented with: Sudden onset right-sided headache, diplopia, right-sided ptosis and hemiplegia ■ Examination: Functional ptosis, bilateral pseudoabducens palsy, restricted up-gaze & collapsing weakness ■ Bloods: Normal (including AchR antibodies) ■ MRI Brain: Mild small vessel ischaemia ■ Infrared Video: Convergence spasm Case One ■ 46 year old male ■ Past history: ‘TIAs’, cluster headache & gastric bypass ■ Presented with: Sudden onset right-sided headache, diplopia, right-sided ptosis and hemiplegia ■ Examination: Functional ptosis, bilateral pseudoabducens palsy, restricted up-gaze & collapsing weakness ■ Bloods: Normal (including AchR antibodies) ■ MRI Brain: Mild small vessel ischaemia ■ Infrared Video: Convergence spasm Case Two ■ 48 year old female ■ Past history: Acute sensory axonal neuronopathy ■ Presented with: Variable fatigue, diplopia, sphincteric disturbance, generalised weakness and ataxia ■ Examination: Inconsistent (normal vs. INO) ■ Bloods: Ganglioside and Ach R Abs negative ■ NCS and MRI Brain: Normal ■ Infrared Video: Convergence spasm Case Two ■ 48 year old female ■ Past history: Acute sensory axonal neuronopathy ■ Presented with: Variable fatigue, diplopia, sphincteric disturbance, generalised weakness and ataxia ■ Examination: Inconsistent (normal vs. INO) ■ Bloods: Ganglioside and Ach R Abs negative ■ NCS and MRI Brain: Normal ■ Infrared Video: Convergence spasm Case Three ■ 16 year old male ■ Past History: Nil significant ■ Presented with: Episodes of diplopia with sustained convergence of right eye lasting less than 24 hours without associated symptoms ■ Examination: − Between episodes: normal − In clinic: pseudoabducens palsy ■ MRI Brain: Normal ■ Infrared Video: Flickers of convergence with pupillary constriction Case Three ■ 16 year old male ■ Past History: Nil significant ■ Presented with: Episodes of diplopia with sustained convergence of right eye lasting less than 24 hours without associated symptoms ■ Examination: − Between episodes: normal − In clinic: pseudoabducens palsy ■ MRI Brain: Normal ■ Infrared Video: Flickers of convergence with pupillary constriction Convergence Spasm: Clinical Issues ■ Poorly characterised & easily misinterpreted 1 : −Disagreement in literature 2 −Miosis on abduction crucial to diagnosis −Difficult to appreciate due to light reflex ■ Commonly an expression of functional disorder 1,2,3 ■ Failure to recognise costly: −Invasive/expensive/ counter-therapeutic investigation ■ Conventional clinical assessment imperfect: −Study of inter-rater reliability:agreement in 75-88% of cases 1 Limitations of Technique/ The Future ■ Infrared video goggles: −Relatively expensive −Limited availability −Training/familiarity with software −‘Snapshot 'of fluctuating condition ■ Report of only three cases ■ Larger studies needed to substantiate the technique ■ Potential research tool e.g. prevalence organic vs. functional disease Figure 2: Still image of patient (case one) demonstrating convergence spasm: note pupillary constriction on attempted abduction (left eye) a Figure 3: Infrared images of patient’s eye (case one) demonstrating convergence spasm. Eye in neutral position (a) and on attempted abduction (b) b References 1.Journal of Neurology Neurosurgery and Psychiatry 2012; 83: 202-204 2.Survey of Ophthalmology; 40 (4): 269-278 3.Practical Neurology 2009; 9: 179-189