A case of psychogenic Parkinsonism: Late age of onset should not be a barrier to make the diagnosis

To the Editor

Psychogenic (functional) Parkinsonism (PP) is an uncommon form of functional movement disorder with a prevalence of 1.5% of all patients referred for Parkinsonism (Sage and Mark, 2015). Published literature till date showed that the typical mean age range of patients with PP is 37–53 years.

A 76-year-old man was referred for a psychiatric assessment for a suspected PP by his geriatrician, as he had non-progressive Parkinson’s disease (PD) along with non-response to dopaminergic medications in the context of poor coping at home and concerns raised by his daughter. He presented with bilateral upper and lower limb tremor with an unsteady gait and slowness of movements. He was diagnosed PD 6 years ago by a neurologist. Sudden onset of restless legs, tremor, bradykinesia and gait abnormality characterized his earlier symptoms, leading to a diagnosis of PD. He received carbidopa and levodopa for 5 years with no benefit, but interestingly, with no deterioration of symptoms typically seen in PD. There was no history suggestive of depression, anxiety or cognitive impairment. He had an unusual blend of rest, postural and action tremor of both upper and lower limbs. His tremor varied in intensity and frequency during examination using various distraction techniques. At times, he hyperventilated and appeared taking considerable effort to complete a motor task. There was no cogwheel rigidity. His gait was ataxic with typical astasia–abasia. A previous magnetic resonance imaging (MRI) brain revealed an old, small size incidental meningioma, not requiring any intervention.

The diagnosis of PP was made on clinical characteristics and absence of a clinical course typically seen in patients with PD (Koukouni and Bhatia, 2007). The major challenge of this case was to make a definitive diagnosis of PP because he has previously been diagnosed and treated with PD and had a much later age of onset. However, the characteristic nature of the unusual combination of neurological symptoms and the variation in intensity and frequency with distraction suggested that it was unlikely to be due to PD (Bhatia and Schneider, 2007). Although the presence of psychological factors is helpful in making the diagnosis, clinical experience is that either this is not present or not available at the time of assessment in about 50% of patients. Careful and detailed examination of the abnormal movements and demonstrating the inconsistency are key aspects of making a correct diagnosis of PP and late onset should not be a barrier to diagnose PP. Table 1 shows some of the clinical indicators of making a diagnosis of PP.

Table 1.

Clinical pointers suggesting a diagnosis of Psychogenic Parkinsonism.

1. Acute onset of symptoms with the absence of a typical course or deterioration seen in Parkinson’s disease.

2.  Unusual or bizarre combination of tremor and various gait abnormalities, especially the presence of astasia–abasia.

3. Variability in the intensity and frequency of abnormal movements using distraction techniques.

4.  Excessive fatigue and labored attempt to complete motor tasks.

5.  Deliberate slowness of movement.

6.  Marked disability even at the onset of symptoms.