Localized Upper Back Pain: A Rare Variant of Restless Legs Syndrome

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J Sleep Med. 2024;21(2):123-125

Publication date (electronic) : 2024 August 31

doi : https://doi.org/10.13078/jsm.240008

Seungwon Song¹, Namoh Kim², Yong Woo Shin³, Ki-Young Jung^,4

¹Department of Neurology, Yonsei University College of Medicine, Seoul, Korea

²Department of Neurology, Nowon Eulji Medical Center, Eulji University School of Medicine, Seoul, Korea

³Department of Neurology, Inha University Hospital, Incheon, Korea

⁴Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea

Address for correspondence Ki-Young Jung, MD, PhD Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu Seoul 03080, Korea Tel: +82-2-2072-4988 Fax: +82-2-2072-2474 E-mail: jungky@snu.ac.kr

Received 2024 April 29; Revised 2024 July 5; Accepted 2024 July 29.

Abstract

INTRODUCTION

Restless legs syndrome (RLS) is a chronic sensory-motor neuron disorder characterized by an urge to move the legs with abnormal sensations and pain, which occur during sitting and resting and are relieved by movement [1]. In accordance with the revised International Restless Legs Syndrome Study Group (IRLSSG) diagnostic criteria for RLS, RLS is diagnosed based on five diagnostic criteria: 1) urge to move, 2) worsening during rest, 3) relief by movement, 4) worsening in the evening or night, and 5) not explained by other medical or behavioral conditions (e.g., myalgia, leg edema, leg cramps, positional discomfort). Although RLS typically affects the lower limbs, localized sensations in the chest, lower back, abdomen, arm, and perineum have also been reported. In unusual cases, the diagnosis can be made by applying the above five diagnostic criteria to other body parts [2-4]. There has been only one report of idiopathic RLS localized to the upper back [5]. Therefore, we present a rare variant of RLS involving the upper back.

CASE REPORT

The patient was a 74-year-old man who had been experiencing discomfort and pain in the left upper back for 20 years (Fig. 1). The patient initially reported experiencing pain in the left upper back, which subsequently radiated to the shoulder. He visited an orthopedist and underwent shoulder radiography, cervical magnetic resonance imaging (MRI), and shoulder MRI. However, no specific diagnosis could be made. Despite administration of analgesic agents for several years and despite acupuncture treatment, no improvement was observed. The symptoms were only present during rest periods, accompanied by an urge to move, relieved by tapping the shoulder and upper back, and alleviated by activity rather than rest. The symptoms are more pronounced at night, leading to insomnia and a reduced quality of life. Notably, the patient did not experience any discomfort or pain in his legs, which is typically observed in patients with RLS.

Fig. 1.

Distribution of discomfort in this patient.

Thirteen years ago, the patient was empirically prescribed pramipexole at a local clinic, which resulted in temporary improvement in symptoms. However, 5 years ago, the patient began experiencing symptoms during the daytime. After the dose of pramipexole was increased to 1 mg daily, the symptoms worsened and persisted throughout the day. Consequently, the patient sought treatment at our hospital.

The International Restless Legs Syndrome score was 34, the Pittsburgh Sleep Quality Index score was 12, the Insomnia Severity Index score was 17, and the Epworth Sleepiness Scale score was 11. Physical examination of the upper back revealed no remarkable findings, such as local pain or tenderness. The patient was 167 cm tall, weighed 69.0 kg, and had a body mass index of 24.7 kg/m². Neurological examinations revealed no abnormalities. The brain MRI results were within the normal range. Ferritin and iron levels were within the normal range (155.0 μg/L and 87 μg/dL, respectively), and the iron saturation was 28%. Polysomnography was performed to investigate abnormalities during sleep, such as periodic limb movement (PLM), obstructive sleep apnea (OSA), and sleep fragmentation. There was no PLM; however, sleep efficiency was poor at 50.4%. Sleep latency was 2.7 min, with no issues observed in the onset of sleep itself. However, sleep maintenance was problematic with frequent awakenings (Table 1). Given an apnea-hypopnea index of 22.9 and OSA, the patient might have experienced difficulties with sleep maintenance and relatively short sleep latency.

Table 1.

Polysomnography findings

Given the possibility of augmentation associated with the high dosage of pramipexole, the pramipexole dosage was gradually reduced, and pregabalin 50 mg twice daily was introduced to manage symptoms. However, after two weeks of pregabalin treatment, the patient’s symptoms worsened, and he began experiencing leg symptoms. Subsequently, pregabalin was discontinued, and the patient was initiated on prolonged-release oxycodone-naloxone (5 mg/2.5 mg, Targin). Following a onemonth course of prolonged-release oxycodone-naloxone, the patient’s symptoms improved.

DISCUSSION

RLS is a well-known sensory-motor neuron disorder characterized by an urge to move the legs, often accompanied by uncomfortable sensations and pain during rest periods, which are relieved by movement. This case report presents a rare variant of RLS involving localized upper back pain, a phenomenon documented only once in the medical literature. The distinctive presentation of RLS in the upper back represents a significant challenge to our understanding of the disorder and underscores the need for further investigation.

RLS is primarily diagnosed based on the revised IRLSSG diagnostic criteria, which include an urge to move, worsening of symptoms during rest, relief with movement, worsening in the evening or nighttime, and the exclusion of other medical or behavioral conditions that may explain the symptoms [1]. In this case, the patient exhibited a classic urge to move, which was alleviated by tapping his upper back and shoulder and relieved by physical activity. Additionally, the symptoms were more pronounced at night, which is consistent with typical RLS patterns. Notably, the absence of discomfort or pain in the lower limbs, which is commonly observed in RLS cases, underscores the rarity of this upper back variant.

The localization of RLS symptoms in the upper back of this patient raises intriguing questions regarding the underlying pathophysiology of RLS. Although RLS is typically observed in the lower limbs because it correlates with the motor cortex and spinal cord, upper back involvement suggests the potential involvement of other neural circuits or anatomical structures [6]. It is essential to consider alternative mechanisms for the localization of RLS in the upper back, such as the potential involvement of the cervical spine or specific sensory pathways.

Furthermore, the patient’s response to pramipexole, a common dopaminergic agonist used to manage RLS, was noteworthy. Initially, pramipexole provided temporary relief; however, an increase in dosage led to a worsening of symptoms and the emergence of daytime symptoms. This phenomenon is consistent with augmentation, a well-known complication of long-term dopaminergic treatment in patients with RLS, further supporting the diagnosis of RLS in this case [7].

This report also highlights the challenges in the diagnosis and management of atypical cases of RLS. The absence of specific diagnostic criteria for localized upper back RLS highlights the necessity for more comprehensive guidelines that can be tailored to accommodate the atypical presentations of the disorder. Recent research has demonstrated that RLS symptoms may manifest in a multitude of locations beyond the legs, with the potential to affect various parts of the body as subtypes of RLS [7]. Therefore, emphasis on the necessity for further research is increasing, with a particular focus on establishing criteria for diagnosing and assessing variants of RLS.

In conclusion, this case report presents a rare variant of RLS involving localized upper back pain and expands our understanding of the diverse manifestations of this sensory-motor network disorder. The absence of discomfort or pain in the lower limbs and the unique response to medication highlight the complexity of diagnosing and managing atypical RLS. As the current literature lacks reports on idiopathic RLS localized to the upper back, this case contributes valuable information to sleep medicine and neurology. More research is necessary to elucidate the underlying mechanisms of localized upper back RLS and develop effective treatment strategies for such cases.

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