GETTING TO THE BOTTOM OF SYRINGOMYELIA

MQ Health researchers have published the largest recent series of outcomes for patients receiving a shunt to treat Syringomyelia, showing that shunts can work well in selected cases.

Characterised by cystic cavities in the spinal cord, Syringomyelia typically causes pain and motor and sensory deficits, and is most commonly association with Chiari malformation or spinal injury.

Traditional treatment is to address the underlying condition. For patients with Chiari malformation, this involves creating more space at the base of the skull for fluid to flow between the head and the spine.

While this works well for Chiari malformation patients, for other groups of Syringomyelia patients where the underlying cause is unclear or where treatment of the underlying condition is too risky, there remain no consensus methods.

“Treatment of Syringomyelia is generally aimed at addressing the underlying cause,” said Professor Marcus Stoodley, Head of the Neurosurgery Research Group at MQ Health.

“However, underlying causes are not yet well understood. For this reason, we are focusing our research on understanding the pathophysiology of the disease.”

Patient Case Series: Redefining the Role of the Shunt

Given the rarity of Syringomyelia, surgeons around the world perform surgical shunt treatment infrequently and, in general, these procedures have yielded a poor success rate, with infection and blockages often resulting, and revision surgery common.

“At Macquarie University Hospital, we see large numbers of Syringomyelia patients,” explained Professor Stoodley. “We have gained a lot of experience – both clinical and laboratory – as part of our long-term research program.

“Having gathered significant knowledge on Syringomyelia, we now have a good idea of when a shunt is indicated.

“Using pre-operative MRI and intra-operative ultrasound imaging to understand the variability of causes has meant we can identify the specific pathology and can then adapt surgical techniques and employ the team’s skills in advanced microsurgery.

“So we determine not only when a shunt is indicated, but what particular surgical combinations or adjustments should be made to increase its effectiveness for each individual patient.”

Professor Stoodley and colleagues have recently published the world’s most comprehensive and contemporary series, looking at outcomes in syrinx to subarachnoid shunt surgery in 41 patients.

The retrospective analysis shows results from the series – including where no known cause or when treatment of the underlying condition has been insufficient or is not feasible – treated between 2000 and 2016 have now been published in World Neurosurgery. Results show that 90 per cent of cases experienced rapid and sustained reduction of the syrinx, and 98 per cent of cases had stabilisation or improvement of neurological signs and symptoms.

In contrast to the adverse outcomes reported in older case series, there was no incidence of infection, shunt malfunction, or spinal cord injury in the current cohort, and no decline in post-operative quality of life as reported by patients.

Up to 108 months post-operatively, just three of the 41 patients (7 per cent) required re-operation for recurrence or enlargement. This is superior to the rates of re-operation following syrinx to subarachnoid shunting previously reported, which ranged from 17 to 33 per cent.

“This case series demonstrates that in patients experiencing deteriorating neurological function, a syrinx to subarachnoid shunt is a safe and effective treatment for Syringomyelia with no known cause or when treatment of the underlying condition has been insufficient or is not feasible,” said Professor Stoodley.

“The consistent efficacy of a syrinx to subarachnoid shunt, despite the diversity of pathologies in the current cohort, suggests shunting can be effective in many cases and the current findings should be broadly generalisable to other patients with Syringomyelia.”

Cervicothoracic Syringomyelia: Understanding Sub-types

A second series of cases published looks at a sub-category of patients – those with scarring of the sub-arachnoid space at the juncture between head and spine, known as craniocervical junction arachnoiditis (CCJA). This scarring can be caused by previous surgery, by trauma or by infection. CCJA is commonly known to be associated with Syringomyelia. Treatment remains challenging with recurrence rates exceeding 50 per cent.

“Our research revealed these patients develop a specific kind of syrinx,” said Professor Stoodley. “So our treatment by posterior fossa decompression – opening up the space at the base of the brain – releases the fluid and is usually effective.

“The key, again, is the pathology of individual patient’s case. Patients showed a variety of pathological features, and surgical strategies should change slightly depending on the individual case.”

Looking Ahead: Ongoing Research to Heal, Learn and Discover

The Neurosurgery Research Group at MQ Health is also conducting ongoing investigation into assessing the dynamics of fluid flow in the spinal cord. Researchers have found that fluid here flows differently to in the brain.

“We have always thought pressure changes and pulsations from heart and breathing influence fluid flow,” said Professor Stoodley. “So now we are closer to understanding how this might cause a syrinx to develop – how other physiological processes affect fluid flow.

“Our thinking is that if we can regulate fluid flow in the spinal cord, then perhaps we can decrease the development of syrinx progression.”

The team is in the early stages of investigation into altering water flow in the cord to determine whether syrinx can, ultimately, be treated by drug therapy. Preliminary evidence suggests that increasing flow through cell membrane water channels might decrease syrinx size, leading to the possibility of treating the condition medically rather than surgically.

Work undertaken by the Spinal Group is based on an integral link between clinical work with patients and laboratory-based research in understanding the disease.

Laboratory work helps to understand the best clinical path for a patient, with treatment data then helping to determine next steps in the lab.

“One can’t happen without the other,” says Professor Stoodley. “Macquarie University Hospital’s unique model of healthcare means that learning and healing go hand-in-hand. The discovery of new knowledge informs treatment and treatment informs directions for new discoveries.

“We’d like to see a range of treatments, enabling us to treat more effectively according to the individual cause.”

Macquarie Medical Imaging (MMI) also plays a vital role in understanding the pathology of Syringomyelia. Amongst other activities, researchers from the Neurosurgery Group are working with MMI specialists to optimise MRI sequencing for patients with Syringomyelia.

Macquarie’s Syringomyelia research has been supported by grants from the NHMRC, and from a Syringomyelia research foundation based in the United States, The Column of Hope.