Surgical outcomes of tethered cord syndrome in patients with normal conus medullaris and filum terminale without urologic symptoms.

Abstract

Tethered cord syndrome (TCS) typically presents with urologic symptoms and abnormal imaging findings. However, some patients present with normal conus medullaris level and filum terminale appearance on MRI. This research seeks to assess the intended surgical results in this particular group of TCS patients who do not present with urologic complaints, under the premise that the surgical approach goes a long way in preventing the onset of urologic abnormalities. This retrospective study included 59 operated patients with tethered cord syndrome who had a normal level terminating conus medullaris and a normal looking filum terminale without urologic symptoms. Of these patients, 38 were female and 21 were male. All patients underwent somatosensory-evoked potentials (SSEPs), and magnetic resonance imaging (MRI). The surgical technique used was flavotomy, which involves cutting the filum terminale without performing a laminectomy. The study population had a mean age of 22.5years (SD = 13.2). During the mean postoperative follow-up period of 2.5years, none of the patients developed urinary incontinence. Preoperative SSEP abnormalities included conduction block in 39 patients (66.1%), low amplitude in 12 patients (20.3%), and delayed N22 wave latency in 8 patients (13.5%). The surgical procedures were completed without morbidity or mortality, and all patients showed significant postoperative improvement in SSEP parameters. Our results indicate that even though the filum terminale might have a normal looking MRI, TCS can also occur due to some potential microscopic or structural abnormality. The study proves SSEP to be useful in TCS diagnosis and it also proposes that if surgery is done early before any urologic complaints arise, chances of their onset will be minimized. Such findings support the view that surgical measures should be entertained in symptomatic patients with abnormal SSEP but normal MRI.