Tethered Cord Syndrome and the Conus in a Normal Position

Abstract

The intent of this article is to propose the existence of the tethered cord syndrome in patients whose conus is in a normal position. The tethered cord syndrome has been a well-recognized entity, occurring in the pediatric and adult population. A central tenet to this syndrome is that the conus medullaris must be "abnormally" low, regardless of the tethering lesion. Our 12-year series of 73 patients with tethered cord syndrome included 13 patients in whom the cord terminated at or above the L1-L2 space. These patients otherwise displayed characteristics usually associated with the patient with an abnormally low conus. Most patients with progressive neurological deterioration responded to surgery. The preoperative radiographic evaluation and the operative findings usually demonstrated a thickened filum. Tethered cord syndrome may occur in the patient who has a conus in the "normal" position.

Tethered Cord Syndrome: An Updated Review

“…Since there is great variability in the conus level amongst patients without symptoms of TCS, it is reasonable to consider the possibility that patients exist with symptomatic cord tethering with a conus medullaris that is considered to be at a normal level. The terms ‘occult TCS’[82,83,84] and ‘occult filum terminale syndrome’[ 85] have been used to describe this purported condition, a concept first raised by Khoury et al[ 86] in 1990, and expanded on later by Warder and Oakes[ 87, 88]. In most of their cases, other findings of occult dysraphism were present (cutaneous stigmata, vertebral anomalies, or thickened fila).…”

Comparison of standard, prone and cine MRI in the evaluation of tethered cord

“…In addition, thickened and/or fatty filum terminale, prior surgery/ trauma or tumor may lead to tethering of the cord. In TCS, the conus medullaris is frequently low in position (tip located below the L2-L3 interspace) [2][3][4]. Tethering of the spinal cord causes abnormal stretching and tension, which results in a variety of neurological symptoms.…”

Study on the Pathomorphology of Myelodysplasia

“…A tethered cord is not the only cause of neurological deficits. An elongated cord was not found to be an essential feature of TCS [16,17,18]. The expansion of TCS to adult and adolescent patients revealed an incidence of 30% of no elongation of the spinal cord and thick filum [19, 20].…”