The prognosis of fixed dystonia: A follow-up study

Abstract

Background

The syndrome of fixed dystonia includes both CRPS–dystonia and psychogenic dystonia. The underlying mechanisms are unclear, but a high prevalence of neuropsychiatric illness has previously been reported.

Methods

Clinical and neuropsychiatric follow-up study by telephone and self-administered instruments (HADS, SDQ-20, DES II, EQ-5D), on 41 patients with fixed dystonia after a mean of 7.6 (±3.6) years.

Results

We obtained information on clinical outcome in 35 (85.4%) patients and neuropsychiatric questionnaire data in 22 (53.7%). Eighty-three percent were women. Thirty-one percent had worsened, 46% were the same and 23% had improved, of whom 6% had major remissions. At follow-up, mean duration of illness was 11.8 (±4.9) years and mean age 43.2 (±14.8) years. Except for 1 patient who was re-diagnosed with corticobasal degeneration, the diagnosis remained unchanged in others. Forty-one percent had scores indicating anxiety and 18% indicating depression; 18% scored within the range of dissociative/somatoform disorders on DES II and 19% on SDQ-20. The mean EQ-5D index and VAS scores were 0.34 and 56.1%. Comparison between the 3 outcome groups revealed significant difference only in the EQ-5D (p = 0.003). Only baseline CRPS predicted a worse outcome (χ² = 0.006).

Conclusions

Our findings revealed that the prognosis of this syndrome is poor, with improvement in less than 25% of patients, major remission in only 6% and continued worsening in a third. A high rate of neuropsychiatric findings was noted and new neuropsychiatric features had occurred in some. Average health status was poor. Of the baseline parameters, only CRPS predicted poorer outcome.

Introduction

The syndrome of fixed dystonia is characterized by fixed, abnormal posturing of the distal limb(s), often following a trivial peripheral injury [1], [2], [3], [4], [5], and may occur as part of complex regional pain syndrome (CRPS) [1], [2], [3], [4], [5], where it is also known as causalgia–dystonia [3] or CRPS–dystonia syndrome [2]. Often, the dystonia is severe and disabling, with progression to other body parts, and leads to a significant impact on the patients' overall quality of life [5]. For the purpose of this paper, we have used the term fixed dystonia, as previously described [1] to encompass focal, fixed dystonia of the limbs, regardless of whether there is associated CRPS or psychogenic dystonia (PD) [1], [6]. Despite the recognition of this syndrome, little is known about the underlying pathogenesis. Although it has been argued that dystonia in the context of CRPS is unlikely to be psychogenic [7], in a previous review of 103 patients with fixed dystonia, we found that overlap exists between CRPS and PD [1]. In most patients, the presence of an underlying somatoform or other psychiatric disorder only became apparent following a structured neuropsychiatric interview [1]. The yield was even higher when the primary care records were examined, implying that an underlying psychiatric illness may be under-diagnosed in these patients during the usual outpatient clinic consultation [1]. Furthermore, little is known about the long-term clinical progression in these patients and the impact on their overall quality of life, and, whether an underlying psychiatric diagnosis becomes more evident later in the course of the illness.

We therefore conducted a follow-up study to determine the clinical and neuropsychiatric outcomes on the 41 prospectively assessed patients out of the overall group of 103 patients described previously by the authors [1].