Slides
Transcript
So, good afternoon. I’d like to thank the conference organizers for the invitation to be here today as both a former leaker and physiotherapist to present on physical therapy in the context of CSF leaks.
So, understandably, there are many questions about appropriate physical therapy intervention for both those with current leaks and those recovering after sealing of a leak, and any recommendations need to be based on the best available evidence. When we talk about evidence in healthcare, many of you have probably seen this – it is considered to be a hierarchy referred to as the evidence pyramid, with the strongest evidence coming from meta-analysis and systematic reviews at the top of the pyramid, research like case series and single case studies offering weaker evidence, and basic science at the bottom of the pyramid.
So, what have we got to inform physical therapy choices in the context of CSF leak? Sadly, nothing but the foundation stones are in place at the moment. However, we do have a lot of basic science that can inform our approach to spinal CSF leak recovery, and true evidence-based practice incorporates this along with both the clinical judgment of the health professionals involved and, importantly, the values and preferences of the patient.
So, it’s impossible in a 15-minute presentation to provide a specific program of safe and effective physical therapy for every individual, as there are really so many unique considerations for each person. There will be differences in focus and options depending on the stage the patient’s at, such as whether they’re currently leaking, immediately after sealing, or later in their rehab, as well as individual factors including co-occurring conditions like past injuries or connective tissue disorders, which are prevalent in our patients, individual patient preferences, the degree of limitation that they may have experienced from the leak, how long they’ve been leaking, and the type of procedures undertaken – if any – to seal the leak.
But if we take a look at the underlying anatomy, physiology, and pathology of the dura and neural system, this can inform our choices at all stages.
So, our first priority is always to do no harm. We want the leak site sealed, and so that first priority in the early stages is reducing excessive stress that may put the leak repair at risk. The recommendations, therefore, to limit bending, lifting, and twisting in the initial stages after a repair have been well covered in a previous presentation by Laura Freed. And if you haven’t seen it, I encourage you to watch that. I’ll put up a link later on.
In the time we have today, I wanted to try to expand on these guidelines and highlight some other areas of physical therapy intervention that could help leak patients to optimize their health and potentially improve the likelihood of achieving both a durable leak repair and a return to full functional capacity. So, I’m therefore going to work through some of the anatomy and mechanics of the dura and central nervous system to highlight opportunities for interventions that could positively influence the patient outcomes in leak management and to highlight some important considerations that can guide the general principles of PT, with the goal to provide some information and ideas that any leak patient can consider together with their team and potentially apply to their particular situation. Noting, of course, that nothing here is designed to replace the advice of your own care team.
So, a very basic but important principle underlying physical therapy management in leaks is recognizing that the neural system doesn’t just have to conduct electrical nerve impulses like household wiring to be fully functional. It needs to do this while it’s constantly moving. The brain, cord, and dura move constantly in response to your cardiac cycle and vascular flows, breathing, and any other changes in intra-abdominal or thoracic pressure or body movements and posture changes. All of these things create changes in pressure, length, position of nerve cells, and their associated tissues like the dura, blood vessels, and supporting structures.
So, we shouldn’t be under any illusions that we can remove all mechanical load and movement from the dura to protect it. It will move, and it needs to move for a person to function at any level. What we’re really trying to do is to keep the loading appropriate to the capacity of the dura at that point in time.
This will mean fairly significant limitations in the immediate period after a leak repair, but as healing progresses, we do want to support the intrinsic healing process to optimize recovery of tissue integrity and the capacity for it to manage physiological loads, in order that the leak site and the entire neurological system has the capacity to cope with the demands placed on it by everyday activities.
Another important thing to remember is that the central nervous system is not a discrete structure. It’s actually continuous with the entire nervous system, extending to every extremity of the body. Therefore, all movements of the spine and of the limbs impact the CNS mechanically. Because of this mechanical continuity, forces on the peripheral nerves transmit to the connected CNS structures, including the dura. So, patients with symptomatic hypermobility disorders, like Ehlers-Danlos Syndrome, are at increased risk of both CSF leaks and nerve entrapments and subluxations in the periphery.
By managing these peripheral nerve entrapments and subluxations – things such as thoracic outlet syndromes, piriformis syndromes, peroneal nerve subluxations – it is possible to reduce mechanical loading of the dura. Physical therapists can treat these conditions in multiple ways, but it’s essential that the therapist is aware of the leak history so that treatment strategies can be modified appropriately to avoid adding unnecessary, inappropriate load to the dura in the process.
So, moving into the spine, it probably does seem quite obvious that spinal movement and movement of the CNS structures influence one another. But, in order to more effectively and safely implement physical therapy for a patient with a history of CSF leak, it’s important to understand a few more specifics of the interaction.
If we look inside the spinal canal, the dura and cord are suspended by various structures connecting it to the spine, such as a variety of ligaments and the nerve roots connecting to the periphery. At either end, it has significant attachments via the filum terminale – an elastic tissue connecting the bottom of the cord to the coccyx – and at the junction between the base of the skull and the top of the neck, a structure known as the myodural bridge connects the dura and muscular skeletal structures. We’ll come back to it later.
So, if we have a look at the impact of bending and straightening – or flexing and extending – the spine, the spinal canal in an average person of average mobility is 5 to 9 cm longer in flexion, and it’s quite likely that it lengthens significantly more in hypermobile people, which is a significant proportion of our patients, again. So, the dura normally accommodates this lengthening and shortening through folding and unfolding of coils and folds of tissue, as well as its elasticity and stretching at the end of range.
So, in the images here on the left, hopefully, you can see that as the spine extends backwards, there’s a folding of the dura as well as of the nerve roots as the spinal canal shortens. On the right-hand side, as the spine is flexed and the canal is lengthened, the folds in the dura straighten out, as do the nerve roots.
In addition to the folding and telescoping of tissues and the elasticity, various tissue layers also need to slide past each other during these movements, such as the dura sliding relative to both the spinal canal structures and the cord itself. Without this ability to slide – such as if the dura becomes adhered to any adjacent structures – then stretching forces on the tissues could be increased.
Looking at rotation of the spine, it has the effect of narrowing the spinal canal in some areas and causes stretching through the connecting ligaments and nerve roots that connect the spinal cord and peripheral nervous system. It’s been estimated that where one vertebra is rotated relative to the next, the associated nerve root can be stretched by a full centimeter, transmitting this stretch to the attached dura. So, these effects are relevant not just for intended spinal rotation, like turning to look over your shoulder, but also for rotation of individual spinal segments, such as what we sometimes see in patients with muscle imbalances and segmental instability, where we might have one segment resting rotated relative to another.
So, movement of the dura, central nervous system, and spine are interdependent, suggesting that establishing good control of spinal movement has potential protective effects on the dura. There are multiple factors potentially impacting the spinal movement control in CSF leak patients.
Simple past injuries in the spine can leave lasting control issues if they’ve not been fully treated. As already mentioned, many of our leak patients have underlying connective tissue disorders, and these are associated with impaired proprioception – or the awareness of body position – as well as the laxity of the connective tissues. This results in reduced control or stabilization of the joints in many of these patients, with a noted tendency for spinal segmental instability. Bed rest – which, let’s face it, can be a big part of leak life – is known to lead to reduced muscle function quite globally throughout the body, but especially so in the deep joint-stabilizing muscles, potentially leading to exacerbating existing impairments of stabilizing function.
So, training of both the proprioception – or positional awareness – and the function of the stabilizing muscles of the spinal joints could therefore reduce unwanted dural loading. This is something that could be worked on with a physical therapist even while a patient is on bed rest.
Another benefit here is that people with impaired spinal stabilization often compensate by bracing the larger trunk muscles. This increases intra-abdominal pressure and hence CSF pressure. And further, impaired spinal stabilization can involve pelvic floor dysfunction, which can contribute to bowel and bladder dysfunction, including constipation, which can further increase intraabdominal pressure and ICP. So, facilitating effective muscle control of the spine can also remove multiple pressure stresses from the dura.
A region of the spine where musculoskeletal control potentially interacts with the dura even more than the rest of the spine, and so I believe deserves special attention, is in the upper neck just below the skull. Here, a group of muscles have direct attachments to the dura in the space between the skull and C1 vertebra and between C1 and C2. This complex of muscle and connective tissue blending into the dura is referred to as the myodural bridge, or MDB. The MDB has only fairly recently been identified but is believed to have roles in controlling the folding of the dura during spinal movement, assisting circulation of CSF, as well as stabilizing the head and upper neck, and providing proprioceptive – or positional – information.
Again, there are many factors in CSF leak patients that can contribute to dysfunction in this region that may be responsive to physical therapy intervention. So again, our patients with CSF leak have a high rate of connective tissue disorders, which also predisposes them to instability of the upper neck. This can lead to increased demand on these muscles in their stabilizing role which can transmit load to the dura or through the MGB.
It can also directly raise the intracranial pressure due to the effects of these muscles on CSF circulation between the cranial and spinal compartments. With the limited knowledge that we have regarding the detailed function of the MDB, it seems that it may also play a sensory role in sensing head position – but also sensing dural mechanics and CSF dynamics. So, it’s possible that its function will be disturbed by the altered CSF pressure and flow during an active leak, and so may benefit from rehabilitation after sealing of a leak.
Any disturbance of the myodural bridge’s function could interact with other cranial nerve effects of a CSF leak to impair a person’s sensory motor control, or their ability to integrate the information from their vestibular, visual, and proprioceptive sources – which could contribute to ongoing symptoms of imbalance and visual difficulties. There are PT- guided interventions available that can begin addressing these functions and optimizing general movement and postural control around the neck – even for patients who are still largely on bed rest, as well as those who are able to be upright.
So, POTS – we’ve heard a bit about, but other forms of orthostatic intolerance and POTS are highly prevalent in patients with connective tissue disorders, and studies have shown a very high rate of POTS presentation among those with leaks. POTS symptoms are known to be exacerbated by deconditioning and may contribute to continued intolerance of upright postures after sealing of a leak. Many leak patients could implement some preventative work even while leaking, in the form of some type of aerobic conditioning if possible, and exercise of leg muscles to support venous return of blood to limit the impacts of POTS on their recovery.
So, in summary, with an understanding of dural mechanics and factors that can influence loading of the dura, it’s possible for physical therapy intervention to be modified to treat coexisting conditions without unnecessary risk to the dura. But the therapist must be aware of the history of leak, as loading of the dura can be affected by many factors.
In addition, we can also identify specific interventions that might be considered as part of a program to assist recovery from a leak – by considering the biomechanics of the dura and neural system, common co-occurring conditions present in parallel to a leak, and the secondary effects of the leak itself, such as deconditioning and cranial nerve dysfunction. These include, but are definitely not limited to, firstly treating neurovascular entrapment and subluxations the patient may have that may be transmitting force through to the dura; optimizing muscular control of the spine at all levels – but especially the cranio-cervical junction, where functional instability can impact dural loading; optimizing sensory motor control or the coordination of that visual, vestibular, and joint position sense to assist in movement control and address some of the issues that may arise due to the leak effects; conditioning of the cardiovascular system to overcome bed rest effects – particularly if the patient has POTS or some other form of orthostatic intolerance; and along with this, establishing good breath mechanics is important as well. It can assist not just in the fluid circulations, but also pain management and general well-being; conditioning of the general body musculature, particularly the legs – this can have positive effects on both the orthostatic intolerance by increasing venous return, but also supporting functional movement patterns with less loading of the spine, such as lifting.
So, there’s really too much to talk about in considering planning physical therapy in the context of CSF leaks to cover in a 15-minute presentation. I’ve included a few links here to Laura Freed’s past talk on the precautions after repair, as well as some resources that I’ve been trying to collate to support clinicians providing therapy for CSF leak patients. That includes the full reference list and bibliography for this talk. Thank you.