Timing Important For Tethered Cord Surgery

July 31, 2007 -- Tethered Cord Syndrome (TCS) is a complicated (or some would say not well defined) condition where the spinal cord is placed under abnormal tension. Since the tethering usually occurs near the base of the cord, common symptoms include bowel and bladder problems and leg weakness. Over time the traction, or stress, on the cord can cause nerve damage.

TCS can be due to a number of causes, the most notable of which may be spina bifida, where the protrusion of the spinal cord can attach, or tether to bone. Similarly, some people have lipomas, or deposits of fatty tissue, which can adhere to the spinal cord tissue and essentially anchor it. Another type of adhesion can develop from scar tissue due to previous surgery or infection.

The spinal cord can also be put under tension by an abnormal filum terminale. The filum is a fibrous thread which connects the lower end of the cord to the bony spinal column. A healthy filum has a certain amount of elasticity, however some people are born with filums that are fatty, which reduces their elasticity, and essentially pulls the entire cord down.

Treatment for TCS is usually surgical and involves freeing whatever is tethering the cord; removing a lipoma or sectioning the filum terminale for example. Although treatment for TCS is straightforward, diagnosing it can be difficult and people can go years before being properly diagnosed.

While clinicians have always thought early diagnosis and treatment was better, recently, two surgeons from Slovakia wanted to see if this all too common delay in diagnosis had an impact on surgical outcomes. To do this, they studied the outcomes of 22 children they treated over a 15 year period. They published their results in the June issue of European Journal of Pediatric Surgery.

Of the group, nine children improved after surgery, eleven were unchanged and two got worse (see Table 1). Interestingly, the average duration of symptoms for the improved group was about 16 months, compared to 52 and 54 months for the unchanged and worse groups. Further, the doctors noted that those treated within the first six months of symptoms experienced the best outcomes.

Table 1
Surgical Outcomes and Average Time to Treatment

Outcome # of Patients Avg Time (months)
Improved 9 16.7
Unchanged 11 52.4
Worse 2 54

Statistically, those treated in the first year were 24 times more likely to have a better outcome and nearly every patient treated in the first year improved. However, only 25% of those treated after the first year improved.

Does this mean there's a 12 month window for diagnosing and treating TCS after symptoms become apparent? This study is too small to say conclusively, but it is strongly suggestive that early intervention may be key.

Research into adult TCS may also support this notion. One study (Rajpal et al.) found that less than half of adults treated for TCS experienced long term improvement. This low success rate could be because their TCS went undiagnosed for a long period of time.

This finding is especially important for the Chiari community because it can sometimes be difficult to sort out the root cause of symptoms. If a person has Chiari, a syrinx and a tight filum, the tight filum may go unnoticed because the symptoms may be assumed to be due to the Chiari and syrinx. Or, if someone's symptoms recur some time after Chiari surgery it can be difficult to determine whether the decompression was insufficient or if scarring has led to the cord becoming tethered.

Adding to the diagnostic confusion is the recent, and controversial, idea that not all tethered cords can be seen on MRI. Some doctors and researchers believe that the filum terminale can put the spinal cord under enough pressure to cause symptoms, but that it can not be seen on MRI. This is referred to as Occult TCS.

The good news is that clinicians and researchers are becoming more aware of the possible overlap between Chiari and TCS and are working to improve diagnosis.

Related C&S News Articles:

Controversy Surrounds Occult Tethered Cord Syndrome

Surgical Outcomes For Adult Tethered Cord Surgery

Possible Biomarkers Found For Tethered Cord

Chiari Linked To Lipomyelomeningocele

New Study Casts Doubt On Tethered Cord Causing Chiari

MRI Documents Acquired Chiari Due To Fatty Filum

Minimal Tethered Cord Shows Abnormal Anatomy