Syringomyelia is a neurological disorder characterized by the formation of a fluid-filled cavity, known as a syrinx, within the spinal cord. This cavity develops longitudinally, expanding over time to compress and damage surrounding nerve tissue. Post Traumatic Syringomyelia (PTS) is an acquired form of this condition that arises as a delayed complication following a spinal cord injury. PTS can manifest months or years after the initial trauma, often leading to slow but progressive neurological deterioration in individuals who had previously reached a stable level of recovery.
The Mechanism of Syrinx Formation
The formation of a syrinx following trauma is primarily rooted in the disruption of the normal flow dynamics of cerebrospinal fluid (CSF), the clear liquid that bathes the brain and spinal cord. The initial spinal cord injury triggers a healing process that frequently results in scarring and inflammation in the subarachnoid space surrounding the cord. This scar tissue, medically termed arachnoiditis, physically obstructs the path of CSF circulation around the spinal cord.
The blockage creates an abnormal pressure gradient, preventing the CSF from moving freely as it normally would with the pulse and respiration cycles. This pressure imbalance forces CSF into the central canal or through damaged tissue and enlarged perivascular spaces within the spinal cord parenchyma. The fluid then begins to accumulate within the spinal cord, leading to the formation of the syrinx cavity.
Once formed, the syrinx tends to expand because of a suspected one-way valve mechanism that allows fluid to enter the cavity more easily than it can exit. Activities that temporarily increase venous pressure, such as coughing, straining, or heavy lifting, may contribute to this expansion by transmitting pressure to the cyst. This progressive expansion of the syrinx cavity damages the spinal cord’s nerve fibers, leading to the onset of new or worsening neurological symptoms.
Recognizing the Symptoms of PTS
Symptoms of PTS often represent a significant change for a patient who had been neurologically stable following their initial injury. A hallmark sign is the development of new or worsening chronic pain, particularly a burning or aching central neuropathic pain that can spread superiorly from the original injury site. This pain is distinct from musculoskeletal pain and is often challenging to manage with standard pain medications.
Sensory changes are also frequently observed, including a loss of sensitivity to temperature and pain, while the sense of touch may remain intact, a phenomenon known as dissociated sensory loss. When the syrinx is located in the cervical (neck) region, this sensory loss can affect the shoulders, arms, and upper chest in a pattern sometimes described as a cape-like distribution. These sensory deficits result from the syrinx expanding into and damaging the fibers responsible for transmitting pain and temperature signals across the spinal cord.
As the syrinx grows, it can compress motor pathways, leading to the development of new muscle weakness or a functional decline in previously spared areas. Patients may notice increased muscle stiffness or spasticity, as well as a loss of muscle bulk, particularly in the hands and arms. Furthermore, the expanding cyst can affect the autonomic nervous system, manifesting as new episodes of autonomic dysfunction, changes in sweating patterns, or alterations in bowel and bladder control.
Diagnosis and Progression Monitoring
The diagnosis of Post Traumatic Syringomyelia relies on a combination of a detailed neurological examination and advanced imaging. During the physical exam, a physician looks for the characteristic signs of progressive neurological deterioration, such as new sensory deficits or motor weakness above the level of the original injury. These clinical findings serve as the initial suspicion that prompts further investigation.
Magnetic Resonance Imaging (MRI) is considered the most reliable tool for confirming the diagnosis, as it clearly visualizes the fluid-filled cavity within the spinal cord. The MRI scan provides detailed images that show the exact size, length, and location of the syrinx, often revealing it as a distinct bright signal on T2-weighted images. Specialized MRI techniques like cine-MRI may be used to assess the dynamics of CSF flow around the spinal cord and within the syrinx itself.
Even if symptoms are mild or absent, regular monitoring is necessary to track the condition’s stability. Sequential MRI scans are often performed to track any changes in the syrinx size over time, which is an indication of its progression. This systematic approach allows healthcare professionals to intervene before irreversible damage occurs.
Treatment Options for PTS
The management of Post Traumatic Syringomyelia is tailored to the individual patient, depending on the severity of symptoms and the rate of syrinx progression. For syrinxes that are stable, small, and cause minimal or no symptoms, a conservative approach involving monitoring is adopted. This management typically includes physical therapy to maintain function and pharmacological intervention to manage chronic pain and spasticity.
When a syrinx is expanding or causing significant, progressive neurological deterioration, surgical intervention is generally recommended to halt the progression of damage. The main goal of surgery is to decompress the spinal cord by draining the syrinx fluid or by restoring the normal flow of CSF around the cord.
One common surgical technique involves placing a shunt, a thin tube, into the syrinx to drain the fluid into another body cavity, such as the abdomen (syringoperitoneal shunt). Another surgical strategy focuses on addressing the cause of the CSF flow obstruction by removing the scar tissue or tethering that formed after the original injury. Procedures like spinal cord untethering or terminal ventriculostomy—which involves sectioning a terminal cord structure—may be used in specific cases to improve fluid drainage. While surgical intervention is often successful in stabilizing or improving motor function and pain, it may not fully reverse neurological deficits that have already occurred.