Unique, Not Psychological Movements: Painful Leg Syndrome and Toe Movement

A 74-year-old woman visited our department for several months due to the nagging pain prevalent in the feet. She had a history of chronic back pain. Neurological examinations showed normal results other than involuntary movements. Nerve conduction study, electroencephalography, and brain MRI revealed unremarkable findings, while spinal MRI revealed mild lumbar spinal stenosis. Due to the typical unique movements, i.e. bilateral toe movements, which are asynchronous and consist of extension, flexion and, in rare cases, abduction, she was diagnosed with painful moving toe syndrome. Administration of duloxetine resulted in partial pain relief and reduced movements. We considered that clinicians should be aware of this unique movement disorder in order to avoid misdiagnosis of psychiatric conditions.

an introduction

Painful legs and toes (PLMT) is a rare motor condition defined by pain in one or more limbs and accompanied by repetitive, irregular toe movements. [1]. It was first reported by Spillane et al. As a disease associated with lower extremity pain and involuntary movements of the toes in 1971 [2]. The exact pathophysiological mechanism is unknown [3]. The intensity of the pain varies greatly between individuals, and ranges from constant discomfort to severe pain. In addition, some patients had no identifiable cause for the pain. Thus, doctors may make the movements for a psychological condition. Here we report on an elderly woman who was diagnosed with painful leg syndrome with moving toes. The video shows typical unique movements, ie bilateral toe movements, which are asynchronous and consist of extension, flexion and, in rare cases, abduction. Multiple neurological examinations showed unremarkable results.

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A 74-year-old woman with a history of chronic back pain experienced a dull, predominant pain in the feet for several months. Neurological examination, manual muscle testing, muscle tone, and deep tendon reflexes showed normal results. The straight leg elevation and femoral nerve stretching tests were unremarkable. Sensory disturbance was minimal except for pain during spontaneous toe movements, that is, spontaneous bilateral toe movements, which were asynchronous and worse on the left, were visible (video 1).

Movements consist of extension, flexion, and, rarely, abduction of the toes, which were often visible during a state of rest, including during sleep. In addition, movements were not inhibited by many tasks, including eye closure, arithmetic, and auditory stimuli. A nerve conduction study showed unremarkable results. The EEG showed a well-regulated dominant posterior rhythm, from 9 to 10 Hz. There was no epileptic or sluggish discharge. Needle electromyography showed no denervation. While the MRI of the brain showed normal results, the spinal MRI showed mild stenosis of the lumbar spine. There were no abnormal signals on the dorsal root nerve. Work on a malignant tumor showed negative results. Hence, the patient was diagnosed with pain in the legs and toe syndrome (PLMT). Oral diazepam and pregabalin were not effective in reducing pain and movements. Duloxetine (20 mg / day), in combination with pregabalin, produces partial pain relief and reduced movements.

Discuss

Although the causes of PLMT are diverse, clinical factors associated with the disease have been noted. PLMT is more common in females (66%) with an age of onset ranging from 24 to 86 years [3]. Risk factors for PLMT include peripheral neuropathy, prior trauma, and radiculopathy, but the conditions are often idiopathic. [3]. Although the present case contains MRI findings of mild (L5) radiculopathy, this finding is common in the general elderly population. Thus, it was difficult to prove causation in the present case. False is an important differential diagnosis in our case. However, the somatosensory system including deep sensation was normal, along with normal findings in the dorsal nerve on MRI of the spine. Thus, pseudogout was minimal in our case. It should also be noted that some cases with PLMT had a history of malignancy [3]. Thus, action on malignancy is critical in patients with PLMT (negative results were shown in our case).

The involuntary movements in PLMT were continuous and there was a gradual increase and decrease in the degree of symptoms. Even if the onset of symptoms was unilateral, more than half of patients eventually developed bilaterally. In addition, patients were able to stop their involuntary movements transiently with intent or by applying pressure to the sole of the foot. [4]. The involuntary movements that occur in PLMT are unique and qualitatively different from traditional involuntary movements (tremor, myoclonus, and spasticity). [5]. Thus, doctors may easily mistake this condition as a psychiatric condition. However, the involuntary movements seen in PLMT are sharply different from the involuntary movements commonly observed in psychiatric disorders (eg, post-traumatic dystonia) [6]. More specifically, there were no psychomotor features in our case, such as 1) atypical symptoms, 2) increased symptoms with attention and decreased with distraction, 3) accompanied by spurious muscle weakness, and 4) multiple distribution and pattern of movements [7].

Previous studies showed that both pain and involuntary movements were drug-resistant [3,8]. Involuntary movements are usually associated with the intensity of pain in PLMT [9]. Treatments for pain rather than movement gave a degree of relief to the current condition, as seen in another study [3,10]. Given this discrepancy, it is likely that several pathological mechanisms appear to be involved in PLMT.

Conclusions

Here, we report an elderly woman diagnosed with PLMT. The video shows typical unique movements, while multiple neurological examinations have shown unremarkable results. Chronic toe discomfort accompanied by involuntary movements may be caused by PLMT pain. If the patient experiences movements, several investigations should be performed as described in this report. Additionally, clinicians must be aware of this unique movement disorder in order to avoid misdiagnosis of psychiatric conditions.