All 6 patients suffered from chronic daily headaches and were diagnosed with suspected spinal CSF leak based on their clinical and/or radiological findings. Spinal CSF leak may resolve spontaneously or through conservative measures such as bed rest, oral hydration, generous caffeine intake and use of an abdominal binder 22,23; however, this was not seen in our patients. They did not respond to pharmacological treatment, conservative measures and failed multiple interventions including non-directed epidural blood patches and epidural patches targeted at levels outside of the PI fracture site, such as at the level of the contrast enhanced nerve sleeves and extradural collection. This highlights that in many cases of spinal CSF leak, it is imperative to identify the site of spinal CSF leak for targeted treatment with epidural patches to maximize response rate 23. These cases highlight the difficulty in successfully identifying a target site.
The exact location of spinal CSF leak is often unknown. MRI brain may suggest signs of intracranial hypotension (subdural collections, pachymeningeal enhancement, venous engorgement, pituitary hyperemia and brain sagging), but these have no localizing value 23. Spinal imaging such as MRI or CT myelogram can confirm a leak based on contrast in the extradural space or nerve sleeves, but may be falsely localizing 27. Our patients had targeted low volume (3ml each site) epidural patches with fibrin sealant at the site of the PI fractures with significant treatment response (Greater than 50% reduction in pain intensity) at their 3 month return visit, which suggests the PI fractures may be the culprit for their suspected spinal CSF leak. Previous reports have demonstrated intracranial hypotension or pseudomeningocele as potential complications from other orthopedic injuries including spondylolisthesis and vertebroplasty 28,29. PI fractures were detected from the CT myelogram and were missed on the MRI spine in 5 out of the 6 patients. Our cases illustrate an added advantage of CT myelogram in the workup of suspected spinal CSF leak for osseous pathology 30.
Patient 1 demonstrated a transient and mild relief from his non-targeted lumbar epidural patches, which suggests a possibility that prior treatments were coincidentally injected at or near the site of PI fracture since the lumbar region is often a standard location for non-directed epidural blood patches. Limited information was available from the chart review on the other patients’ prior treatment response.
Patients 1 and 4 developed suspected rebound intracranial hypertension 6 months post patch based on a change in their headache characteristics (headache worse lying supine). This information was relayed to our center from their primary providers. This illustrates a potential risk of spinal CSF leak treatment long term. Our patients had a prolonged clinical course before the PI fracture was identified as the suspected leak site. It is possible that contributed to an increased risk of rebound intracranial hypertension 31.
As for the PI fracture, the treatment is usually nonsurgical (rest and bracing). Surgery (laminectomy or posterior lumbar fusion) may be required if symptoms persist or remain bothersome 25. Patient 1 complained of lower back pain, which could be a direct symptom of PI fracture, however his subjective improvement after the patch argued against the PI fracture being the cause and lower back pain is not an uncommon symptom in SIH 20.
Some limitations were seen with this study: Two out of the 6 patients (Patient 1 and 2) met the diagnostic criteria of “headache attributed to low CSF pressure” as per the International Classification of Headache Disorders Third Edition 32. The other 4 patients had suspected CSF leak based on supportive clinical and radiological findings, such as orthostatic headaches, enhancing nerve sleeves and/or favorable response to treatment. All cases were presented at the neuroradiology/headache neurology CSF leak conference and the diagnosis of suspected CSF leak was agreed upon a panel of headache specialists, anesthesiologists and neuroradiologists. Opening pressure was not measured in 5 patients and patient 5 had a normal opening pressure recorded 33. Certainly, a detection of CSF pressure < 6 cm H2O supports the diagnosis of CSF leak, however, it is not uncommon to have a normal opening pressure with CSF leak, especially in chronic CSF leak patients. A normal opening pressure does not rule out a CSF leak 23. All patients reported subjective improvement with their concomitant symptoms at their return visit, but not quantified. Long term follow-up (beyond 3 months) data are not available since our center is a tertiary referral center and our patients returned back to their primary and referring providers for subsequent follow-up. This is a retrospective case series limited by lack of control subjects and small population size. It is also subject to selection and information bias.