Intracranial pressure monitoring for spontaneous intracranial hypotension diagnosis [Neurosurgery Wiki]

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====== Intracranial pressure monitoring for spontaneous intracranial hypotension diagnosis ======

Continuous [[intracranial pressure monitoring]] is definitive for documenting abnormally negative [[intracranial pressure]]s.
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Spontaneous intracranial hypotension (SIH) is a debilitating disorder, with an estimated annual incidence of 3.7 per 100,000. Diagnosing SIH can be challenging for clinicians, as patients frequently present with normal investigation findings. Intracranial pressure (ICP) monitoring has been proposed as a valuable tool for patients with [[orthostatic headache]]s that are highly suggestive of SIH but have inconclusive investigation results. The primary objective of this study was to determine the proportion of patients with spontaneous orthostatic headaches and normal diagnostic work-up who exhibited abnormal ICP monitoring results.

Methods: This single-centre, retrospective observational study was conducted at a tertiary referral centre specialising in SIH and CSF dynamics disorders. Consecutive patients with spontaneous orthostatic headaches and inconclusive diagnostic work-up who underwent 24-hour ICP monitoring were considered eligible. The 24-hour ICP monitoring followed a standardised protocol, measuring median ICP and pulse amplitude (a marker of brain compliance) during the daytime, nighttime, and over the entire 24-hour period. Specific cut-offs for low and high ICP states were predetermined based on the best available current evidence.

Results: Thirty-eight patients (23 females, mean age 41 years ± 14SD) were identified. All patients had orthostatic headaches with a spontaneous onset. The mean duration of symptoms was 46 months ± 36SD. ICP monitoring identified 3 patients (7.9%) with low ICP (mean of the median 24-hour ICP - 2 mmHg ± 2SD) and 6 patients (15.8%) with high ICP (mean of the median 24-hour ICP 9 mmHg ± 3SD). Obvious CSF dynamics disturbances were excluded in the remaining 29 patients (76.3%, mean of the median 24-hour ICP 3 mmHg ± 3SD). The only clinical feature that was more common in patients with abnormal ICP compared to patients with normal ICP results was audiovestibular disturbance, namely aural fullness or muffled hearing (67% versus 17%, p = 0.015). There were no complications from the ICP monitoring procedure for any patient.

Conclusions: When appropriately selected, patients with a clinical picture highly suggestive of SIH, who have a negative diagnostic work-up, may benefit from consideration of invasive ICP monitoring. Moreover, a significant minority of patients with orthostatic headache may paradoxically have a high CSF pressure state, which can be detected using ICP monitoring
((D'Antona L, Cheema S, Mehta D, Bremner F, Watkins LD, Toma AK, Matharu MS. Intracranial pressure monitoring in patients with spontaneous onset of orthostatic headache. J Headache Pain. 2025 Feb 4;26(1):27. doi: 10.1186/s10194-024-01928-7. PMID: 39905291.))
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While this study provides preliminary evidence for the use of ICP monitoring in select SIH cases, several limitations must be acknowledged. A prospective, multicenter study with larger sample sizes and a control group is necessary to validate these findings. Additionally, long-term follow-up studies should evaluate the impact of ICP-guided management strategies on patient outcomes.

Ultimately, ICP monitoring may be a useful adjunctive tool in complex SIH cases, but its routine application requires further validation. Future studies should also investigate whether high ICP findings in orthostatic headache patients represent a separate disorder or an adaptive response to chronic CSF loss.
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A 31-year-old male, presented with subacute onset moderate occipital and sub-occipital headaches precipitated by upright posture and relieved on recumbency and neck pain for 2 years. There was no trauma, cranial/spinal surgery. Clinical examination was normal and CSF opening pressure and laboratory study were normal. Magnetic resonance imaging (MRI) brain showed thin subdural hygroma. Another patient, 41-year-old male presented with 1 month of subacute onset severe bifrontal throbbing orthostatic headaches (OHs). CSF opening pressure was normal. Contrast MRI brain showed the presence of bilateral subdural hygromas, diffuse meningeal enhancement, venous distension, sagging of the brain, and tonsillar herniation. We report two cases of "spontaneous OHs" with normal CSF pressures who were successfully treated with epidural blood patching after poor response to conservative management
((Hassan KM, Prakash S, Majumdar SS, Banerji A. Two cases of
medically-refractory spontaneous orthostatic headaches with normal cerebrospinal 
fluid pressures responding to epidural blood patching: Intracranial hypotension
versus hypovolemia and the need for clinical awareness. Ann Indian Acad Neurol.
2013 Oct;16(4):699-702. doi: 10.4103/0972-2327.120461. PubMed PMID: 24339614;
PubMed Central PMCID: PMC3841635.
)).