Preserved Sensory-Motor Function Despite Large-Scale Morphological Alterations in a Series of Patients with Holocord Syringomyelia

Abstract

Although the central nervous system has a limited capacity for regeneration after acute brain and spinal cord injuries, it can reveal extensive morphological changes. Occasionally, the formation of an extensive syrinx in the spinal cord can be observed that causes no or only limited signs of functional impairment. This condition creates a unique opportunity to evaluate the mismatch between substantial morphological changes and functional outcomes. We identified seven patients with holocord syringomyelia affecting the cervical cord following chronic traumatic thoracic/lumbar spinal cord injury (19-34 years after injury) or holocord syringomyelia of non-traumatic origin, and anatomical syrinx dimensions (length, cross-sectional area) were determined using sagittal and axial magnetic resonance imaging scans. Motorand sensory-pathway integrity were evaluated using electrophysiological assessments (i.e., motor, dermatomal sensory, and dermatomal contact-heat [dCHEP] evoked potentials, as well as nerve conduction studies). These were specifically compared to clinical measures of upper-limb strength and grasping performance, including three-dimensional motion analysis. Despite extensive anatomical changes of the cervical cord (on average 26% reduction of residual spinal cord area and intrusion of almost the entire cervical spinal cord), a clinically relevant impairment of upper-limb motor function was absent while only subtle sensory deficits could be detected. dCHEPs revealed the highest sensitivity by disclosing impairments of spinothalamic pathways. Comparable to that of the brain, extensive anatomical changes of the spinal cord can occur with only subtle functional impairment. The time scale of slowly-emerging morphological alterations is essential to permit an enormous capacity for plasticity of the spinal cord. Although the central nervous system has a limited capacity for regeneration after acute brain and spinal cord injuries, it can reveal extensive morphological changes. Occasionally, the formation of an extensive syrinx in the spinal cord can be observed that causes no or only limited signs of functional impairment. This condition creates a unique opportunity to evaluate the mismatch between substantial morphological changes and functional outcomes. We identified seven patients with holocord syringomyelia affecting the cervical cord following chronic traumatic thoracic/lumbar spinal cord injury (19-34 years after injury) or holocord syringomyelia of non-traumatic origin, and anatomical syrinx dimensions (length, cross-sectional area) were determined using sagittal and axial magnetic resonance imaging scans. Motor-and sensorypathway integrity were evaluated using electrophysiological assessments (i.e., motor, dermatomal sensory, and dermatomal contact-heat [dCHEP] evoked potentials, as well as nerve conduction studies). These were specifically compared to clinical measures of upper-limb strength and grasping performance, including three-dimensional motion analysis. Despite extensive anatomical chang...

Posttraumatic Syringomyelia with Holocord Involvement: A Case Report

“…Syrinx, including the entire spinal cord, has been reported in chiari malformations; however, cases reported in posttraumatic SCI patients are extremely rare. Approximately 10 cases of posttraumatic syringomyelia with holocord involvement have been reported in the literature 1,2,5,7,8) . Generally, symptoms of syringomyelia occur 1 to 34 years after their initial SCI.…”

“…Generally, symptoms of syringomyelia occur 1 to 34 years after their initial SCI. Unlike common posttraumatic syringomyelia, patients with posttraumatic holocord syringomyelia were diagnosed 19 to 34 years after the primary injury 1,2) . Awai and Curt 2) described cases of posttraumatic holocord syrinx where 4 patients were diagnosed with posttraumatic holocord syringomyelia.…”

Post-traumatic syringomyelia with holocord involvement: a case report

“…3 Upon literature review, less than ten cases of a holocord syrinx after post-traumatic SCI have been previously described. 4,5 A study published in the Journal of Neurotrauma by Awai et al 5 described several cases of holocord syringomyelia following thoracic and lumbar traumatic SCI. The patients in that study showed symptoms of Syringomyelia 19-34 years after their initial SCI.…”

Spontaneous resolution of an extensive posttraumatic syrinx

“…7 The thermal stimulus specifically activates Ad nociceptors in the periphery and is propagated through the spinothalamic tract, which is specifically vulnerable in the case of an axially expanding, central syrinx, where horizontally crossing commissural fibers are more susceptible to damage than the longitudinal tracts of the dorsal columns. 5,7 As PTS is invariably noncommunicating with respect to the central canal, the path of expansion may meander somewhat eccentrically within the cord and this likely accounts for the sparing of spinothalamic function at T4 and T7 seen in this case, where axial images reveal the body of the syrinx to be more dorsally located (insets, figure 1B). Spontaneous resolution in PTS is rare but possible and seems to be associated with sizeable posttraumatic cystic lesions, which may represent a therapeutic target in selected cases.…”

“…4 Such expansion likely proceeds relatively atraumatically along tissue planes and may account for the often subtle symptomology encountered, even in anatomically extensive PTS. 5 The sudden and complete radiologic resolution of a syrinx, accompanied by subtotal clinical recovery, is almost without precedent. Interestingly, the only similar report also featured a posttraumatic cyst and the authors suggested that resolution resulted from a rupture of the syrinx cavity into the subarachnoid space.…”