Article Text
PDF
Abstract
Background Convergence spasm refers to transient ocular convergence, miosis and accommodation associated with disconjugate gaze mimicking abducens palsy. While it may be a manifestation of brainstem pathology, this sign is often associated with conversion (somatisation) disorders and, if unrecognised as a sign of a psychogenic disorder, it may lead to unnecessary and occasionally invasive evaluation.
Methods To better characterise this neuro-ophthalmologic sign, 36 subjects were studied, 13 with psychogenic movement disorders, 11 with organic movement disorders and 12 normal controls. Patients were recorded during a manoeuvre to elicit convergence spasm and the videotapes were rated by two blinded raters on a scale of 0=normal, 1=mild convergence spasm and 2=marked convergence spasm.
Results Convergence spasm was present in 9/13 (69%) psychogenic movement disorders cases, 4/11 (36%) non-psychogenic movement disorders cases and 4/12 (33%) controls (p=0.049 when psychogenic vs non-psychogenic disorders or controls were compared). Inter-rater reliability analysis of the presence (rating 1 or 2) versus absence (rating 0) showed good agreement (27/36 or 75%; kappa 0.491, SE 0.141, p=0.002). Analysis for the presence of marked convergence spasm (rating 2) yielded agreement in 32/36 (88.9%) examinations (kappa 0.652, SE 0.154, p<0.001) with a specificity of 87% (sensitivity 15%).
Conclusion Convergence spasm may provide benefit in the clinical examination of psychogenic movement disorders patients.
Statistics from Altmetric.com
Introduction
Also known as spasm of the near reflex, convergence spasm is a neuro-ophthalmologic sign characterised by intermittent episodes of convergence, miosis and accommodation that may mimic abducens paresis.1–5 Frequently associated with psychogenic disorders, also referred to as ‘functional,’ ‘hysterical,’ ‘conversion’ or ‘medically unexplained’ disorders,6 7 the sign has not been well characterised and is often misinterpreted by physicians, even neurologists and neuro-ophthalmologists. As a result, patients who exhibit this sign are often subjected to unnecessary and potentially dangerous diagnostic tests and invasive procedures. In this study, we aimed to characterise convergence spasm and to determine the prevalence of this phenomenon in a population of patients with organic and psychogenic movement disorders and in healthy controls.
Methods
Patients evaluated at the Parkinson's Disease Center and Movement Disorders Clinic, Baylor College of Medicine and their accompanying relatives and friends were recruited for prospective evaluation and grouped into the following categories: patients with non-psychogenic movement disorders, patients with psychogenic movement disorders and healthy controls without evidence of movement or neurological disorders. Consecutive psychogenic movement disorder cases seen in our centre over a 6 month period were recruited for the study and were videotaped by one of the investigators (RF). Consecutive organic movement disorder cases seen by this investigator over 2–3 week periods were also recruited. Controls were recruited from spouses, friends and family members accompanying patients with psychogenic and organic movement disorders to our clinic. The study was approved by the Baylor College of Medicine Institutional Review Board and written informed consent was obtained on enrolment. Prior consent for videotaping was also gathered. Subjects with evidence of brainstem pathology on neurological examination were excluded. None of the subjects or controls had any prior complaint related to headaches, diplopia or blurry vision.
The presence of normal conjugate gaze was assessed by examining pursuit eye movements during tracking of the examiner's finger in all directions. To further ascertain normal, conjugate optokinetic nystagmus (OKN), subjects were then instructed to watch and count stripes as an OKN tape was moved by the examiner in both horizontal and vertical directions. As convergence spasm has been reported to occur as a mechanism to overcome impaired versional movements in patients with horizontal gaze palsy, and amblyopia would interfere with our ability to rate gaze deviation, only subjects with normal conjugate gaze and OKN were included.8 9 To elicit convergence spasm, the subject was instructed to focus on the examiner's finger, with the tip at about 10 cm away from the face, at either extreme lateral gaze for 5 s. The examiner's finger was then slowly brought about 10–20° from the extreme lateral gaze towards the midline and the presence or absence of disconjugate gaze and miosis was noted. Patients were asked if diplopia was present. The oculomotor examination was videotaped and the video segments were later edited, randomised and presented to two independent raters (JFB-C and AH) who were blinded to the diagnosis. They rated the videotaped examination on a three point scale of 0=normal, 1=mild convergence spasm and 2=marked convergence spasm. Inter-rater reliability was evaluated by Cohen's kappa10 using STATA IC V.11 software. The same method was used for analysis of absent (0) versus present (1 or 2) convergence spasm and absent or mild (0 or 1) versus marked convergence spasm (2). Subjects with divergent blinded ratings were rated as 0. Fisher's exact and Kruskall–Wallis tests were used for analysis.
Results
A total of 40 subjects were recruited for the study and prospectively evaluated. Four control subjects were excluded due to disconjugate primary gaze. The resulting cohort consisted of 13 patients (85% women, age 38.9±17.8 years) diagnosed with probable or established psychogenic movement disorders (see supplemental table 1, available online only),11 11 patients (73% women, age 58.5±18.5 years) with organic movement disorders and 12 healthy controls (58% women, age 52.0±14.7 years). Psychogenic movement disorders were diagnosed by the presence of distractible movements with irregular amplitude and frequency which entrain in frequency to volitional movements in the case of tremor, myoclonus and tics as well as by induction with application of vibratory stimulation. Non-psychogenic movement disorder patients included tardive dystonia (n=2), cervical dystonia (n=1), essential tremor (ET) (n=2), Parkinson's disease (PD) (n=1), cranial dystonia (n=3), Tourette syndrome (n=1) and one patient with both ET and tardive dystonia. Convergence spasm was seen in both tardive dystonia cases, PD and the combined ET and tardive dystonia case. Horizontal diplopia during the manoeuvre to elicit convergence spasm was reported by 7/13 (54%) psychogenic, 5/11 (45%) non-psychogenic movement disorder patients and by 2/12 (17%) controls.
Convergence spasm was present in 9/13 (69%) psychogenic movement disorder cases, 4/11 (36%) non-psychogenic movement disorder cases and 4/12 (33%) controls (figure 1). Classification of mild versus marked spasm was based on degree of convergence (figure 2). There was an agreement on convergence spasm scores by the two raters in 24/36 (66.7%) examinations (Cohen's kappa of 0.484, SE 0.121, p<0.001). Classification by presence (rating 1 or 2) versus absence (rating 0) showed good agreement (27/36 or 75%; kappa 0.491, SE 0.141, p=0.002). Analysis for the presence of marked convergence spasm (rating 2) yielded agreement in 32/36 (88.9%) examinations (kappa 0.652, SE 0.154, p<0.001), with a specificity of 87% and a sensitivity of 15% for separation between psychogenic versus organic movement disorders plus controls. The χ2 test of the psychogenic movement disorders group versus healthy and organic moving disorders groups under the same classification yielded a p value of 0.0499. Fisher's exact test trended towards significance with p=0.081 for a comparison of the three groups classified as absent (0) versus present (1 or 2).
Prevalence of convergence spasm among patients with psychogenic movement disorders and organic movement disorders, and in control subjects.
(A) Normal control without convergence spasm. (B) Psychogenic movement disorder patient with mild convergence spasm. (C) Psychogenic movement disorder patient with marked convergence spasm.
Discussion
Our study demonstrated that convergence spasm was a frequently encountered phenomenon, particularly in patients with psychogenic disorders. There was good agreement among blinded raters of convergence spasm. Analysis of the absence versus presence of convergence spasm in the psychogenic movement disorders group showed a significant difference. Analysing for marked convergence spasm yielded high specificity, but this did not reach significance, possibly due to the small sample size. Heterogeneity of the diagnoses of the organic movement disorders group and underlying neuroanatomical substrates may have affected the results.
Other authors have considered convergence spasm to be a frequent psychogenic sign,1 12–18 with 86% female predominance in one study.19 Described by von Graefe in 185615 in two cases of ‘acute spasm of accommodation’, a link between this neuro-ophthalmologic sign and hysteria dates back to the early 20th century when ‘spastic hysterical convergent strabismus’ was reported by Knapp in 1918.12 Bielschowsky described convergence spasm as ‘frequently’ occurring in ‘hysteria’, sometimes as its only symptom.13 In one series of eight patients with convergence spasm, long term (mean 8.3 year) follow-up did not reveal any organic aetiology.14 Besides associated features and history consistent with a psychogenic disorder, response to placebo has also been used to provide support for a psychogenic aetiology. Two patients in the case series of Moore and Stockbridge improved with placebo eye drop therapy.16 18 Diagnosis of convergence spasm by amytal interview and treatment by suggestion has been reported.17 When unrecognised as a sign of a psychogenic disorder, the presence of convergence spasm may lead to unnecessary and invasive procedures. Griffin et al reported five cases with an erroneous sixth nerve palsy diagnosis that resulted in unnecessary ‘carotid arteriography, pneumoencephalograms and craniotomy’.20 Awareness of this sign in psychogenic disorders should enable more accurate interpretation in the appropriate clinical context. The finding of isolated convergence spasm in an otherwise well young person is highly suspicious of psychogenic disease.
Despite its relatively high prevalence there are few data in the literature on the examination technique for convergence spasm and there is no consensus on the diagnostic criteria for this neuro-ophthalmologic sign. While some draw distinction between the near reflex and isolated esotropia or pseudo-sixth nerve palsy,21 others conclude that accommodative spasm may consist of pseudomyopia with or without esodeviation or miosis.3 Although none of our patients had any spontaneous complaints that could be attributed to convergence spasm, during the manoeuvre designed to elicit the sign many patients complained of blurred vision, diplopia, headaches and eye pain, also reported by others.1 19 Convergence spasm is often misdiagnosed as sixth nerve palsy,20 but the presence of miosis helps establish the diagnosis of convergence spasm. A history of episodic diplopia in the setting of normal conjugate eye movements should suggest the possibility of convergence spasm. Since convergence spasm may simulate lateral rectus palsy, normal lateral rectus function can be confirmed using horizontal OKN tape or a vestibulo-ocular reflex manoeuvre.19
In addition to psychogenic aetiology, convergence spasm has also been described in many organic causes, including encephalitis,22 aromatic L-amino acid decarboxylase deficiency,23 tabes dorsalis,24 post-myelography,25 thyroid disease,26 primary failure of accommodation,27 vertebrobasilar ischaemia,28 29 attempts to overcome vertical gaze palsy,30 metabolic encephalopathy,31 multiple sclerosis32 and strabismus.33 The coexistence of other oculomotor signs such as nystagmus or saccadic pursuit point towards structural brain pathology such as head trauma.34 Supplemental table 2 (available online only) lists further case reports of convergence spasm.
In conclusion, testing for convergence spasm should be included in the evaluation of patients with suspected psychogenic movement disorders. Additional studies with larger sample sizes are needed to validate these results.
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Files in this Data Supplement:
- Download Supplementary Data (PDF) - Manuscript file of format pdf
- Download Supplementary Data (PDF) - Manuscript file of format pdf
- Download Supplementary Data (PDF) - Manuscript file of format pdf
- Download Supplementary Data
Footnotes
Competing interests RF and ADH received honoraria from Medlink Inc. JJ has received research grants from the following: Allergan Inc, Allon Therapeutics, Ceregene Inc, Chelsea Therapeutics, Diana Helis Henry Medical Research Foundation, EMD Serono, Huntington's Disease Society of America, Huntington Study Group, Impax Pharmaceuticals, Ipsen Ltd, Lundbeck Inc, Michael J Fox Foundation for Parkinson's Research, Medtronic, Merz Pharmaceuticals, National Institutes of Health, National Parkinson's Foundation, Neurogen, St Jude Medical, Teva Pharmaceutical Industries Ltd, University of Rochester and Parkinson's Study Group. JJ has been a consultant or advisory committee member for Allergan Inc, EMD Serono, Lundbeck Inc, Merz Pharmaceuticals, Michael J Fox Foundation for Parkinson's Research and Teva Pharmaceutical Industries Ltd. He serves on editorial advisory boards of Elsevier, Medlink: Neurology, Neurology in Clinical Practice, Neurotoxin Institute, Scientiae and UpToDate.
Patient consent Obtained.
Ethics approval This project was approved by the Baylor College of Medicine Institutional Review Board.
Provenance and peer review Not commissioned; externally peer reviewed.