Clinical significance of imaging and histological characteristics of filum terminale in tethered cord syndrome

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The pathophysiology of tethered cord syndrome (TCS) is uncertain; however, it has been suggested that fibrous and fatty elements within the filum terminale (FT) play a role. The objective of this study was to describe the radiological and histological features of the FT in TCS and determine if there are associations between those features and clinical outcomes, complications, and urodynamics.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>In this retrospective study, histological, MRI, and clinical data obtained in 293 patients with TCS who underwent FT transection were reviewed and analyzed in a multivariate analysis.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The median patient age was 4.9 years (range 0.3–64.3 years). On MRI, a fatty filum was present in 65% of patients and a thickened filum (&gt; 2 mm) was seen in 45%. Histologically, the FT contained prominent fibrous tissue in 95%, nerve twigs in 79%, adipose tissue in 59%, and vascular tissue in 36%. Histological features associated with a thickened filum on MR images were adipose tissue (OR 3.5, p &lt; 0.001), nerve twigs (OR 2.2, p = 0.028), and vascular tissue (OR 0.5, p = 0.025). Adipose tissue was associated with a conus level below the L2–3 disc space (OR 2.3, p = 0.031) and with a fatty filum on imaging (OR 9.8, p &lt; 0.001). Nerve twigs were associated with abnormal urodynamics (OR 10.9, p = 0.049). The only variable predictive of clinical improvement was conus level; patients with conus levels caudal to L-2 were less likely to improve postoperatively (OR 0.3, p = 0.042).</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Fibrous tissue was ubiquitous and may be important in the pathophysiology of TCS. Nerve twigs and adipose tissue were associated with abnormal urodynamics and low-lying coni, respectively. Although the majority of patients clinically improved, patients with normal conus levels had significantly better outcomes.</jats:p></jats:sec>

Neurological and spinal manifestations of the Ehlers–Danlos syndromes

“…The filum contains neural, glial, and ependymal remnants that stem from embryonic spinal cord which begin to regress at 9–10 weeks of gestation [Jang et al, ]. The presence of fatty tissue, “nerve twigs” (dysplastic axons), fat and vascular lacunes, and suspicion of “congested” veins, are usually seen in the abnormal fila specimens obtained from patients with TCS [Thompson et al, ] Stretching of the spinal cord by the structurally abnormal filum is the presumed mechanism of TCS. Symptoms may become more apparent as a child grows.…”

Morphometric parameters and histological Study of the Filum Terminale of Adult human cadavers and MR images

“…The vascular, biomechanical, biochemical and molecular changes in FT of TCS should be further investigated to clear the pathophysiology of TCS and improve its clinical manifestations [7,8,23]. Further investigation should be done to assess the amount of fibrous, adipose, vascular, and nervous tissues in normal adult fila and comparing them with the fila of TCS.…”

“…Low content of elastic fibres with high content of fat and fibrous structure within the FT can render FT inappropriately tense with subsequent generation of TCS [9]. Low-position of conus, increase initial diameter and fibrous content of FT could induce TCS [7].…”

“…This syndrome is diagnosed by neurological, urological and orthopaedic malfunction [26]. Also, TCS is accompanied by tight filum and low-position of conus below L2 [7].…”

Letter to the Editor: Suboccipital decompression without dural opening

“…While there has been an explosion of neuroimaging studies in SRCs utilizing advanced techniques such as DTI, task-based and resting-state functional MRI, and resting cerebral blood flow, none of these technologies have advanced beyond experimental use. 13 As Dr. Griffin points out, alterations in white matter integrity have been demonstrated in groups of patients with mTBI, 10 but they have also been observed in those who have sustained subconcussive head impacts, 8 and in some cases DTI indices have failed to discriminate between subject groups with and without PCS. 5 While we hope that future technical refinements will help clarify inconsistencies observed among DTI studies in SRC and mTBI, at present the failure of this modality to provide reliable and consistent quantitative biomarkers that can be used to diagnose, classify, prognosticate, or confirm recovery in individual concussion patients leads the authors to question how routine use of this technology would impact clinical decisionmaking in our patients.…”