A review of the disagreements in the prevalence and treatment of the tethered cord syndromes with chiari-1 malformations

BACKGROUND: The tethered cord syndrome (TCS) accompanying Chiari-1 (CM-1) malformations and the occult tethered cord syndrome (OTCS) syndrome accompanying the low lying cerebellar tonsil (LLCT) syndrome may be treated with sectioning of the filum terminale (SFT). METHODS: Utilizing PubMed, we reviewed the neurosurgical literature to determine how frequently spinal neurosurgeons diagnosed the TCS (e.g., conus terminating below the normal L1-L2 disc level) on lumbar magnetic resonance (MR) studies in patients with CM-1 malformations [e.g. tonsils >5–12 mm below the foramen magnum (FM) warranting SFT]. In addition, we assessed how frequently spinal neurosurgeons encountered the OTCS (e.g., conus normally located at L1-L2 on MR) accompanying the LLCT (e.g., tonsils herniated <5 mm below the FM) also requiring SFT. RESULTS: According to the neurosurgical literature, the incidence of TCS accompanying CM-1 requiring SFT ranged from 2.2% to < 6%, and up to 14%. Few studies additionally highly correlated the OCTS accompanying the LLCT syndrome warranting SFT. CONCLUSIONS: Given the differences in the literature, more studies are needed to assess the risks (complications) vs. benefits (improved neurological outcomes) of SFT surgery for TCS with CM-1 and SFT for OCTS with LLCT.