Duplicate filum terminale noted in an adult: a rare finding

Classification of and individual treatment strategies for complex tethered cord syndrome

Objective

To study the classification, diagnosis, and treatment strategies of complex tethered cord syndrome (C-TCS) on the basis of the patients' clinical symptoms, imaging findings, and therapeutic schedule.

Methods

The clinical data of 126 patients with C-TCS admitted to our department from January 2015 to December 2020 were retrospectively analyzed. Classification criteria for C-TCS were established by analyzing the causes of C-TCS. Different surgical strategies were adopted for different types of C-TCS. The Kirollos grading, visual analogue scale (VAS), critical muscle strength, and Japanese Orthopaedic Association (JOA) scores were used to evaluate the surgical outcomes and explore individualized diagnosis and treatment strategies for C-TCS.

Results

C-TCS was usually attributable to three or more types of tether-causing factors. The disease mechanisms could be categorized as pathological thickening and lipomatosis of the filum terminal (filum terminal type), arachnoid adhesion (arachnoid type), spina bifida with lipomyelomeningocele/meningocele (cele type), spinal lipoma (lipoma type), spinal deformity (bone type), and diastomyelia malformation (diastomyelia type). Patients with different subtypes showed complex and varied symptoms and required individualized treatment strategies.

Conclusion

Since C-TCS is attributable to different tether-related factors, C-TCS classification can guide individualized surgical treatment strategies to ensure complete release of the tethered cord and reduce surgical complications.

Tethered Cord Syndrome Caused by Duplicated Filum Terminale in an Adult with Split Cord Malformation

BACKGROUND

Tethered cord syndrome (TCS) is a clinical diagnosis of progressive neurologic aggravation of the lower spinal cord due to a traction on the conus medullaris. Untethering surgery is effective for most TCS; however, when anatomic variations of spinal cord and filum terminale (FT) exist, regular untethering may lead to a failed outcome.

CASE DESCRIPTION

The authors present the case of a 45-year-old patient with TCS caused by duplicated FT with split cord malformation (SCM). Lumbosacral magnetic resonance imaging revealed a type II SCM with a significant low-lying conus medullaris. Laminectomy was performed. Neurophysiologic monitoring was used for nerve root identification and 2 thickened fila, which failed to respond on stimulation, were found during the surgery. Both fila were sectioned, and the diagnosis was finally confirmed by pathologic examination. Postoperatively, the patient's symptoms disappeared immediately and no neurologic sequela was found after surgery.

CONCLUSIONS

This is the first documented adult of duplicated FT with preoperative radiologic evidence and reported in association with SCM as a cause of TCS. When SCM exists, a careful observation for duplicated FT is warranted on preoperative magnetic resonance imaging and during surgery. Complete transection of the double FT under intraoperative neurophysiologic monitoring is the best treatment for this anomaly.

Historical Perspective of Split Cord Malformations: A Tale of Two Cords

INTRODUCTION

Our appreciation and understanding of what is now known as the split cord malformation (SCM) have a long history. The oldest known example of SCM is from roughly AD 100. Other isolated examples can be found in the large body of work of the pathologists of the 1800s, where the SCMs were found incidentally during autopsies.

CONCLUSIONS

SCM has a rich history and has intrigued physicians for over 200 years. Many well-known figures from the past such as Chiari and von Recklinghausen, both pathologists, made early postmortem descriptions of SCM. With the advent of MRI, these pathological embryological derailments can now often be detected and appreciated early and during life. Our understanding and ability to treat these congenital malformations as well as the terminology used to describe them have changed over the last several decades.