Treatment-resistant sensory motor symptoms in persons with SCI may be signs of restless legs syndrome

Abstract

Study design:

Case report on the successful treatment with pramipexole in four men with chronic spinal cord injury (SCI) suffering from refractory symptoms that were previously considered to be manifestations of a post-traumatic spastic syndrome or neuropathic pain.

Objective:

To raise awareness among health professionals regarding the diagnostic and therapeutic possibility of restless legs syndrome (RLS) and periodic limb movements (PLMs) in some patients with SCI responding poorly to conventional treatment for spasticity or neuropathic pain.

Setting:

Neurorehabilitation department of the Rehabilitation Medicine Center of Northern University Hospital, Umeå, Sweden.

Methods:

Medical records and clinical data were retrospectively reviewed.

Results:

All cases obtained treatment with pramipexole, initially 0.09–0.72 mg day⁻¹. Two of the cases had RLS and PLMs, one RLS only and one PLMs only. All four reported symptoms in the lower extremities and one also in the upper extremities. Three patients with residual gait function reported RLS score with/without treatment as follows: 32/11, 37/12 and 33/12. One patient with complete paraplegia (with incomplete RLS score) reported 22/10. After a follow-up period of 16, 20, 43 and 49 months, respectively, all four still reported excellent outcomes. Two remained on initial dosage; one had increased dosage from 0.09 to 0.18 mg day⁻¹ and one from 0.27 to 0.80 mg day⁻¹ during the follow-up period.

Conclusions:

In persons with SCI suffering from infralesional involuntary movements and/or dysesthesia and with poor response to conventional antispastic or analgesic treatment, the possibility of RLS or PLMs should be considered, as these conditions seem eminently treatable.

Introduction

Spinal cord injury (SCI) typically causes an infralesional spastic syndrome. In addition, neuropathic pain at or below the neurological lesion level is common.¹

Spasticity is preferably treated with baclofen, dantrolene sodium and other antispastic drugs,² whereas neuropathic pain usually responds to some degree to tricyclic antidepressants and/or antiepileptic drugs such as gabapentin and pregabalin.³ However, some patients respond poorly to such treatment, raising the possibility of misdiagnosis. One additional neurological condition shown to occur after SCI is restless legs syndrome (RLS).⁴ RLS can either be idiopathic or be comorbid with other disorders. RLS is characterized by unpleasant sensations associated with an urge to move the legs. Symptoms usually appear during evenings or during sleep. In about 80% of cases with RLS, there is the presence of repetitive stereotypical, involuntary movements of the legs, across the hip, knee and ankle joints. This symptom is known as periodic limb movements (PLMs).⁴

In our clinical practice, we have observed chronic SCI cases with troublesome and treatment-refractory symptoms, originally attributed to spasticity and/or central neuropathic pain. On closer scrutiny, they fulfilled the criteria for RLS/PLMs and subsequently responded excellently to the currently recommended treatment for this syndrome, that is, dopamine agonists. Four such cases are described in this case report.

Patients and methods

Between 2005 and 2008, one of the authors (SN) detected symptoms of suspected RLS/PLMs among four SCI patients enrolled at the regional neuro-rehabilitation outpatient center. What drew the attention to RLS/PLMs was that all four reported symptoms mainly during evenings and nights. Those patients with remaining motor function also reported relief when moving their extremities. All four cases were then prescribed oral pramipexole.

Treatment effect and dose adjustments were performed at subsequent outpatient visits, according to RLS scoring⁵ (Table 1), clinical interview and examination.

Table 1 The scoring system for RLS symptom severity, developed by the International RLS Study Group⁵

No other attempts to treat cases of RLS/PLM were done.

Results

Basic patient data regarding age, gender, time since SCI, time since debut of RLS, presence of PLM, neurological and ambulatory status, blood chemistry and treatment information are presented in Table 2. In order to determine whether the diagnosis of RLS was secondary to other conditions, B12, folate, creatinine, serum iron, ferritin and transferrin were measured and were found to be within normal ranges.

Table 2 Clinical data of the four SCI patients

The initial dose of pramipexole varied between 0.09 and 0.72 mg day⁻¹. One patient fulfilled the clinical criteria of RLS, two for both RLS and PLMs, and one for PLMs. All four reported symptoms in the lower extremities and one also in the upper extremities. RLS score was used. Three patients with remaining gait function reported RLS score without treatment between 32/40 and 37/40. One patient with complete paraplegia (with incomplete RLS score) reported 22/32 (Table 3).

Table 3 Treatment and outcome of treatment of the four patients

After a follow-up period of 16, 20, 43 and 49 months, respectively, all four still reported excellent results. Two reported no increase in drug dosage, one had increased drug dosage from 0.09 to 0.18 mg/day and one from 0.27 to 0.80 mg/day during follow-up.

No side effects of pramipexole were reported.

Discussion

The limitations of a case study are obvious and restrict those conclusions that can justifiably be drawn. However, an increased awareness of the possibility of RLS/PLMs in persons with SCI is of importance, as adequate treatment is indeed available and the risk of confusing the patients’ symptoms with those of post-traumatic spasticity and/or neuropathic pain is high. Conventional antispastic and analgesic treatment are unlikely to alleviate the symptoms of RLS/PLMs. In doubtful cases, a trial ex juvantibus with a dopamine agonist such as pramipexole might be warranted.

In conclusion, when treating patients with SCI suffering from infralesional involuntary movements or dysesthesia, especially if conventional antispastic and/or analgesic treatment fails, the possibility of RLS or PLMs should be considered.