An underappreciated complication discovered

Research from Schoen Clinic has made the work of surgeons even safer

The outer layer of the spinal cord and nerve roots is called the dura mater, which derives from the Latin adjective meaning ‘hard.’ But what does ‘hard’ mean in this context? Even the most experienced surgeon cannot always avoid damaging this nervous membrane when they try to relieve pressure from tissues on the nerve roots in the spine’s lumbar region.

This procedure, known as decompression, is the most common operation on the nerve root canal (spinal canal) among older patients. Its significance in health care will grow more in the future, because it can be a means for especially older patients to retain their independence. Narrowing of the nerve root canal (spinal canal stenosis) is considered one of the main causes of pain in the back and legs, and can lead to lasting nerve damage.

The nerve membrane is not visible to surgeons at first

Access to the spinal canal is usually through the arch plate of the vertebra, or the lamina. The bone can only be overcome by pressure, but the nerve membrane (dura) underneath it is not immediately visible to surgeons. Damage to the dura, or duraplasty, can occur during this process, reports the head physician of Spinal Surgery at Schoen Clinic Hamburg Eilbek, private lecturer Dr Ralph Kothe.

Together with six other physicians, in a study published in European Spine Journal in 2017, Kothe examined how these accidental injuries to the nerve membrane affect the healing process and the results of treatment. Before the study, the popular opinion was that this complication could be treated well by stitching or gluing the tear and would have no long-term consequences for the patient.

Severe reduction of pain without complication

The study by Kothe and his colleagues reached different conclusions: when the nerve membrane is not damaged, the length of the stay at the hospital is 6.4 days, and 8.0 days with damage. The difference could clearly be proven even twelve months after the procedure: patients without duraplasty enjoy significantly greater improvement of their back pain. The study shows that damage to the dura per se must be appreciated as a complication.

The support from the hospital was the deciding factor

The advantage of Kothe’s research group was that they could make use of both a very high sample size as well as a very homogeneous group of the patients studied at Schoen Clinic. A total of more than 800 patients from Schoen Clinic Hamburg Eilbek, Neustadt (in Schleswig-Holstein) and München Harlaching took part in the study. Their average age was 70 years old. Schoen Clinic surveyed their patients three and twelve months after the operation and thus have a detailed means for measuring the results of treatment, and from the patient’s perspective.

Kothe knows from his professional experience how tedious it can be to collect data about treatment quality as part of the everyday hospital routine. He previously worked at a large community hospital and took part in the register for the European Spine Association with his department at the time. ‘My team and I were tasked with entering the data. But that did not work out in the daily routine. And it is especially impossible to write to the patients again and then evaluate the responses. This can only work if it is professionalised through independent quality management like in Schoen Clinic,’ he reports. His study depends on a roughly 70 per cent response rate from patients.

The patients benefit directly from the research

The patients benefit directly from the results. Through the evaluation of over 800 data sets, a surgery patient at risk, who for example has a cyst in the spinal canal, can assess and prepare better even before the procedure. Kothe’s work also made progress for benchmarking. Damage to the dura occurred in 6.5 per cent of the cases in Schoen Clinic after this study. ‘Those are hard figures that I can refer to, even when informing the patient about the surgery. At a complication rate of 10 per cent, we would know that something is not right,’ remarks Kothe. Complication rates of between 3-16 per cent are documented in specialist literature.

Spine specialists: