Painful legs and moving toes syndrome –  two case reports

This is an unauthorised machine translation into English made using the DeepL Translate Pro translator. The editors do not guarantee that the content of the article corresponds fully to the original language version.

Dear Editor,

Since lower limb pain is a common reason for visiting a doctor, we present here two case reports of a rare syndrome involving pain and involuntary movements.

Painful legs and moving toes syndrome (PLMT) is a rare condition characterized by pain in one or both lower limbs and involuntary toe movements. This descriptive name was first used by Spillane et al. in 1971 [1]. The type of movement varies and may be flexion, extension, or adduction or abduction. The movements tend to be slow, varying in frequency and amplitude. Some authors liken this movement to playing the piano [2]. The movements can be momentarily inhibited by will. Pain in PLMT is not uniform in nature [3,4]. A wide range of sensations of varying intensity have been described including pressure, unspecified pain, stabbing, spasmodic pain, as well as tickling and other non-painful sensations [3,5]. Pain often precedes the development of involuntary movements. In some patients, toe movement has led to partial transient relief [4]. The etiology and pathogenesis of PLMT remain unclear. In a proportion of patients, the difficulties are secondary to anamnestic trauma or severe polyneuropathy, but the association or mechanism of PLMT in these cases is also unclear [3,6]. Diagnostic criteria, even given the rarity of this syndrome, are not firmly established. It is a combination of typical clinical manifestations while excluding other explanatory pathology.

We repeatedly examined a 71-year-old woman (patient 1) in our outpatient clinic for lower extremity complaints. Family and personal history were not significant.

The complaints began with discomfort on the soles of the feet. Initially, the patient described a coldness, plus spontaneous movement of the toes, which led to relief. During the night, she then registered a sensation of great warmth in her feet.

First, a diagnosis of restless legs syndrome (RLS) was made, although we were aware of the atypicalities with respect to the diagnostic criteria. Serum ferritin was always above 75 μg/l. Standard dopaminergic treatment for RLS did not result in relief; the patient could not tolerate Targin and pregabalin because of side effects. Subsequently, gabapentin 600 mg in the evening partially alleviated the symptoms. After two years, the cold sensation in the fetlocks changed to a persistent but tolerable burning in the legs and tibiae.

Objective neurological findings were repeatedly normal, including thermal and algic sensory examination. During examination of the feet, involuntary movements of the toes were noted during prolonged observation at rest -⁠ they moved individually, non-rhythmically, flexion and extension of sometimes single toes, sometimes multiple toes simultaneously predominated. The movements were completely irregular and choreographed. There were also abduction and adduction movements.

The MRI of the brain and cervical spine showed evidence of mild atrophy of the brain and multiple nonspecific white matter gliosis, otherwise age-appropriate findings. MRI of the thoracic and lumbar spine showed multiple vertebral hemangiomas and spinal canal stenosis at the L2/3 to L4/5 levels. Motor and sensory conduction studies including F wave and H reflex latencies on lower extremity EMG were within normal limits. Blood samples showed a slight elevation of total cholesterol, while other blood tests (iron metabolism, vitamin B9 and B12 levels, thyroid hormones and glycaemia, renal function parameters and liver function tests) were within normal limits.

We diagnosed the patient with PLMT after the character of the unpleasant sensation changed to burning pain in the soles of the feet.

The second case is a 37-year-old man (patient 2) who was examined for suspected sleep-disordered breathing and frequent limb movements in sleep. The patient was treated for esophageal reflux disease and reported chronic vertebrogenic algic syndrome of the lumbar spine. On detailed questioning, the patient described two types of lower limb movements: a) stereotyped, volitional movements of both lower limbs characterized by foot tapping with heel elevation, most often while working on a PC, and b) small, involuntary toe movements, which his wife observed even in sleep almost every night. Neither type of movement was associated with pain, but the patient reported nonspecific discomfort and pressure in the feet in tight, closed shoes.

Objective examination revealed syndactyly in the proximal part of the 2nd and 3rd toes of the right foot. Topical neurologic findings, including thermal and alginate sensory testing, were normal. At rest, mild, irregular to choreatic movements of all individual toes were present -⁠ most prominent were subtle flexion movements followed by extension to the original position, with intermittent mild abduction with adduction.

Nocturnal videopolysomnographic examination revealed mild sleep fragmentation with borderline lower efficiency, mainly due to obstructive sleep apnoea (OSA) and hypopnoea. Repetitive, slow, choreatic and mutually independent toe movements were evident throughout sleep.

Motor and sensory conduction studies, including F wave and H reflex latencies in the EMG examination of the lower limbs were within normal limits. MRI of the lower thoracic and lumbar spine showed only mild degenerative changes at L4/5 and L5/S1. Blood samples (including iron metabolism, vitamins B9 and B12, thyroid hormones, glucose values, lipid metabolism, renal function and liver tests) were normal.

It was concluded that the patient had two independent disorders -⁠ OSA of moderate severity and PLMT without typical limb pain. Rhythmic movement of the lower limbs during wakefulness was evaluated as stereotypy.

The very rare diagnosis of this PLMT may be due to confusion with other diagnoses (polyneuropathic syndromes, RLS, periodic leg movements in sleep, etc.), low awareness of the disease as such, but also to the fact that only a proportion of patients are likely to complain of these problems [3,4]. Patient 2 is an example of PLMT without typically expressed pain, which has already been described in the literature as painless legs and moving toes (PoLMT) [7] -⁠ this phenotype is usually classified as a type of PLMT [5]. Discomfort in tight closed shoes is reported in some patients [3]; however, cases in which wearing socks or shoes relieves pain have also been described [8]. Patient 2 has syndactyly of two toes on the right foot, which has not been described in the literature with PLMT. According to the literature, toe syndactyly is not accompanied by pain or abnormal movements [9].

The cause of PLMT is generally not clarified even in our patients. A universally effective therapy is not known. In some patients, gabapentin or pregabalin alleviate the symptoms, as was the case in patient 1.

The painful lower limbs and mobile toes syndrome aptly names rarely occurring neurological symptoms that occur together and are considered a distinct nosological entity. The present dual case report is intended to highlight this nosological unit, which belongs in the diagnostic balance sheet of lower limb movements and in the balance sheet of atypical lower limb pain.

Grant support

Supported by the National Institute for Neurological Research (EXCELES Program, ID: LX22NPO5107) -⁠ Funded by the European Union -⁠ Next Generation EU.

Conflict of interest

The authors declare that they have no conflicts of interest in relation to the subject of the paper.