Background
Surfers’ myelopathy (SM) is a rare condition first defined by Thompson et al. [1]. It is defined as a nontraumatic spinal cord injury seen in novice surfers who maintained a prone position on the board with hyperextension of the spine for long periods, leading to the onset of back pain and progressive neurological deficits. A vascular mechanism of the disease is related to spinal hyperextension, but its exact pathophysiology remains unclear. This vascular mechanism leads to vascular damage and ischemia to the distal spinal cord segment [2]. The incidence of significant injuries in competitive surfers has been estimated to be 6.6 injuries per 1,000 hours of surfing [3]. Surfers’ injuries are rarely neurological, among them, SM is the most common neurologic injury described in the literature [4]. Although being described in surfers, SM was also described in other sports activities (such as gymnastics, cheerleading workouts, acrobatics, ballet, yoga, and Pilates) and nonsport activities (such as demolition work) [2-6].
Magnetic resonance imaging (MRI) is the most effective diagnosis method, usually showing high T2 hyperintensities in the thoracolumbar spinal cord, representing cytotoxic edema stemming from spinal cord infarction. Several treatment paradigms have not proven to be effective in the management of this syndrome [2].
We described a second opinion case seen in our institution with clinical and imaging characteristics of SM, in which another diagnosis was proposed before. Written informed consent was obtained from the patient for the publication of this case report.
Case Presentation
A 33-year-old woman, without previous medical history, manifested that she was practicing for the first time an aquatic sport. While she was lying down in a prone position on a board, towed by a motor boat, she suddenly felt a painful sensation in her lower back and 20 minutes later she developed paresthesia and loss of strength in her lower extremities. The next day she lost sensibility from the belly button down and developed urinary retention. She was treated in a general hospital for post-traumatic myelitis and received methylprednisolone 1 g/day for 5 days without improvement. Thoracic-spinal cord MRI showed T2 hyperintensities involving the central part of the spinal cord between T8 and T12 (Figure 1). Over the course of 1 year of treatment with physical therapy, she achieved better control of the trunk and sphincter with no improvement in strength and sensation in the lower extremities.
She came to our institution for a second opinion 1 year later. On examination, she was oriented, with paraplegia, hypotonia, areflexia, and atrophy in lower extremities with sensitive disturbance from T10 down. The second MRI a year after the injury showed atrophy of the spinal cord from T11 down (Figure 2). A diagnosis of SM was made for this patient, and physical therapy was offered.
Discussion
SM is a poorly known entity, which can be confused with other types of myelopathies. The body of literature remains small and the majority of information to date is case series and case reports. As we have seen in our case, another diagnosis was proposed at first, post-traumatic myelopathy. When reviewing the history, imaging, and evolution of the case in our institution, we concluded that this case is an example of SM.
Thompson et al. [1] reported nine cases of inexperienced surfers, during their first surfing class, they developed atraumatic back pain followed by paraparesis or paraplegia, and sensory and sphincter disturbances. All cases in this series reported an increased T2 signal in the thoracic spinal cord. Thereafter, multiple case reports were published with the same clinical and imaging characteristics while practicing different sports and nonsport activities [5,6]. Our patient developed lower back pain while practicing a water sport followed by sudden onset of motor, sensitive, and sphincter involvement, these findings are consistent with the literature.
Given the sudden development of symptoms, the most universally accepted etiology of the disease is vascular [1]. Being a spinal cord hyperextension the trigger event of ischemia in the distal spinal cord. Alternative etiologies proposed are compression of the inferior vena cava and embolization within the spinal arteries [2,7]. Within the hypotheses proposed as pathophysiological mechanisms of this entity, we have: 1) vasospasm of Adamkiewicz artery; 2) perforating vessel avulsion; and 3) fibrocartilaginous embolism [1,2].
As we have seen in our patient, MRI characteristics are very important for the diagnosis, as well as the history of spine hyperextension. Our patient shows extensive involvement of the lower thoracic spinal cord, leading to severe spinal cord atrophy 1 year after the onset of symptoms. Nakamoto et al. [8] found similar MRI characteristics in the distribution of spinal cord hyperintensities; he described MRI of 23 patients within 24 hours of the first symptom and found “pencil-like” T2 hyperintensities in the central region of the spinal cord from mid-thoracic segment down. Diffusion-weighted images (DWIs) are recommended to identify ischemic involvement, our case did not have DWI [9]. In Chile, Too-Kong et al. [10] reported two cases that found dissection of the left radicular artery, postulating the dissection as the pathophysiological mechanism of disease. Spinal angiography was seldom used as a diagnostic tool in this group of patients, perhaps due to the lack of resources or capacities of the primary care center.
The prognosis of the disease depends on the aggressiveness of the initial lesion. Aggressive cases or complete paraplegia have been reported, in which patients failed to see significant neurological recovery [1,2]. Our case was very severe from the beginning, and 1 year after the injury the patient had paraplegia and atrophy in the lower extremities, reflecting the severe damage produced in the spinal cord. The prognosis may be poor for patients who show severe paraplegia in the acute stage; therefore, they should receive long-term physical therapy to achieve independence in activities of daily living [11].
Understanding SM pathophysiology and increasing awareness of the disease can lead to early detection of cases and avoiding misdiagnosis. Our case highlighted the importance of awareness of the condition in neurologists and first-level physicians to avoid unnecessary diagnostic procedures and medical or surgical treatments in cases where disease mechanisms are clearly reported by the patients.
The most important procedure to prevent SM is preventative measures. Surfers and other aquatic sport practitioners should be instructed to prevent prolonged hyperextension of the spine.