RE:

Dear Editor,

We thank Dr. Radaideh and colleagues for their interest in our work1. CSF leaks, particularly when spinal in origin, can not only be debilitating but are underdiagnosed, and more awareness will benefit patient care.

Our study found that skull base CSF leaks do not typically present with clinical symptoms or brain MRI findings associated with spontaneous intracranial hypotension (SIH). The correspondence by Dr. Radaideh and colleagues question whether underlying intracranial hypertension accounts for the absence of brain MRI findings that we associate with spinal CSF leaks causing SIH.

Of the 31 patients with skull base leaks included in our study, 3 (9.7%) had the diagnosis of idiopathic intracranial hypertension (IIH), 15 (48.4%) had a history of trauma or temporal bone surgery, and 13 (41.9%) were classified as spontaneous. Of the spontaneous cohort, 7 had CSF pressure measured (mean 18.8 cm H2O, SD 3.1). As a reference, IIH consensus guidelines use >25 cm H2O as a cutoff.2 Patients with baseline IIH who decompress as a CSF leak could potentially fall below the 25 cm H2O cutoff.

We believe that the more convincing evidence in our work contrary to the letter by Dr. Radaideh and colleagues lies in the 48.4% of patients with trauma or surgery, rather than IIH, that led to the skull base CSF leak. One of these patients had a posterior fossa leak with brain MRI findings of SIH, otherwise the remainder did not. That cohort provides evidence that skull base CSF leaks do not typically present with brain MRI findings for the reason outlined in our manuscript.

Furthermore, the claim by Dr. Radaideh and colleagues of, “half of the studied patients potentially never had intracranial hypotension and so the imaging signs were naturally absent”, tying low CSF pressure to SIH is a known myth.3-6 This claim, when perpetuated, can lead to the incorrect underdiagnosis of SIH and have a detrimental effect on patient care.

Ian Mark
Jamie Van Gompel

1. Mark IT, Cutsforth-Gregory J, Luetmer P, et al. Skull Base CSF Leaks: Potential Underlying Pathophysiology and Evaluation of Brain MR Imaging Findings Associated with Spontaneous Intracranial Hypotension. AJNR Am J Neuroradiol. Aug 15 2024;doi:10.3174/ajnr.A8333
2. Mollan SP, Davies B, Silver NC, et al. Idiopathic intracranial hypertension: consensus guidelines on management. J Neurol Neurosurg Psychiatry. Oct 2018;89(10):1088-1100. doi:10.1136/jnnp-2017-317440
3. Kranz PG, Gray L, Amrhein TJ. Spontaneous Intracranial Hypotension: 10 Myths and Misperceptions. Headache. Jul 2018;58(7):948-959. doi:10.1111/head.13328
4. Yao LL, Hu XY. Factors affecting cerebrospinal fluid opening pressure in patients with spontaneous intracranial hypotension. J Zhejiang Univ Sci B. Jul 2017;18(7):577-585. doi:10.1631/jzus.B1600343
5. Luetmer PH, Schwartz KM, Eckel LJ, et al. When should I do dynamic CT myelography? Predicting fast spinal CSF leaks in patients with spontaneous intracranial hypotension. AJNR Am J Neuroradiol. Apr 2012;33(4):690-4. doi:10.3174/ajnr.A2849
6. Kranz PG, Tanpitukpongse TP, Choudhury KR, et al. How common is normal cerebrospinal fluid pressure in spontaneous intracranial hypotension? Cephalalgia. Nov 2016;36(13):1209-1217. doi:10.1177/0333102415623071