Evidence review makes the case for further research into Tethered Spinal Cord

An evidence review on the diagnosis and treatment of tethered spinal cord, a rare condition affecting the nervous system, found that, while surgery could be a good option for symptomatic patients, data showing the benefit of surgical intervention for asymptomatic patients was lacking. The review was just published in the journal Pediatrics.                                                                                                                                                     

The work was initiated by the Congress of Neurological Surgeons (CNS) and commissioned and funded by the Agency for Healthcare Research and Quality (AHRQ) and the Patient-Centered Outcomes Research Institute (PCORI), respectively.

Tethered spinal cord is a relatively rare congenital disorder caused by tissues not separating appropriately during fetal development.  As a result, the spinal cord is abnormally tethered to surrounding tissues. It is associated with excessive spinal cord and nerve tension and can lead to movement problems, pain, weakness, and numbness.  It is usually diagnosed in childhood. 

First author Patrick Hsieh, MD, a neurosurgeon at Keck Medicine of USC, along with Susanne Hempel, PhD, director of the Southern California Evidence Review Center at Keck School of Medicine of USC, and a team of researchers, reviewed 103 peer-reviewed studies and 355 case series on 13 databases covering diagnosis and treatment of tethered spinal cord. Topics included prophylactic surgery, treatment for symptomatic tethered spinal cord, and treatment for retethering. The team also obtained data from publication authors for use in the evidence review.

The team’s goal was to identify areas where guidance around diagnosis and treatment could be developed, and where there are knowledge gaps that need to be addressed. 

“We are always trying to diagnose symptomatic patients expeditiously, said Hsieh, who is also a professor of clinical neurological surgery at the Keck School of Medicine of USC.  “Without timely diagnosis and treatment, patients can suffer from neurological decline, leading to pain and functional disability.”

In terms of diagnostics, the team found MRI to be the most reliable tool. Hempel notes that while many diagnostic methods are used, MRI alone had a critical mass of study data supporting use in accurate diagnosis.

When it comes to treatment, Hempel says surgery in symptomatic patients seems to have good results. However, she and Hsieh believe more research is needed to aid providers and parents in this decision. There are risks of complications as with any neurosurgery. Performing surgery too young will not avoid the need for subsequent surgery years later after the spine has further developed. 

While the disease was assumed to be progressive if left untreated, the review also demonstrated that not all patients with a tethered spinal cord will significantly decline if they don’t have surgery.  

“Surgery should be offered to patients if it can improve neurological functions or halt neurological deterioration, said Hsieh.  “However, asymptomatic patients may not necessarily decline neurologically, and surgeons should be careful about the over-aggressive approach to treating asymptomatic tethered cord patients surgically, as the complications of surgery may outweigh the benefits of spinal cord detethering.”

While surgery in symptomatic patients was the only treatment approach for which the team found substantial research, the potential benefit of prophylactic surgery in asymptomatic cases was lacking in evidence, and other approaches had also not been adequately studied.

 “There’s very little information on what happens if we don’t do surgery, or if we manage this conservatively, you know with symptom control,” explains Hempel, who is also a professor of clinical population and public health sciences at the Keck School of Medicine. “What was most striking to us was how little comparative data we really have.” 

The reviewers acknowledge that the rarity of the disease creates inherent challenges in studying it. In most instances there is no control group, leaving no way to compare and comprehensively assess the results of a treatment. 

“We have a collection of empirical evidence – actual operations that people have done with some information of what the clinical impression was, but we want to estimate treatment effect sizes, we want to know the relative risk compared to other management approaches, we want to quantify potential improvements and know the probability of an adverse event, said Hempel. So that’s where the information is lacking.”

It is also difficult to know how patients may have progressed naturally without intervention. Some patients are diagnosed as adults; however, the spine is usually assessed only after other potential causes of symptoms are ruled out, with no history of imaging over time for researchers to refer to. 

“We don't have enough patients in prospective observational cohort studies with clinical details and radiographic studies that accurately tell us the true natural history of tethered cord syndrome on most tethered cord patients,” said Hsieh. “Indeed, research that closely follows tethered cord patients without surgical treatment over a long period is urgently required.”

The reviewers suggest a need for future studies to combine centers, both to amass a larger sample size and create two comparable groups utilizing different treatments. With so little existing information, Hempel believes treatment groups could be either patient-selected or investigator assigned, but she notes a critical piece – “You need to follow them until they are fully grown.”

Hempel admits following patients for decades may not be feasible for an individual researcher. 

“An institution could potentially make a commitment to put together a database and follow up with patients periodically,” she suggests, noting that some of the information needed, like instances of re-operation, would exist in hospital records anyway.

Ultimately, the reviewers hope more will be done to produce information for patients, providers, and parents. Hempel is especially sympathetic when such life-altering care decisions affect small children. 

“We don’t know, even after all these years, whether there’s a real advantage to doing surgery prophylactically and to what extent different treatment strategies affect quality of life or other patient-centered outcomes,” says Hempel. “It’s a scary decision and it’s not clear cut.”

About the study

Authors of the study are Patrick Hsieh, MD, Eric Apaydin, PhD, Robert G. Briggs, MD, Dalal Al-Amodi, MD, Andrea Aleman, Kellie Dubel, Ariana Sardano, BS, Judy Saint-Val, BA, Kim Sysawang, Diana Zhang, Sachi Yagyu MLS, Aneesa Motala BS, Danica Tolentino MS, and Susanne Hempel, PhD.

The work was initiated by the Congress of Neurological Surgeons (CNS) and commissioned and funded by the Agency for Healthcare Research and Quality (AHRQ) and the Patient-Centered Outcomes Research Institute (PCORI), respectively.