Intracranial hypotension: diagnosis by trial of Trendelenburg positioning and imaging
Our patient’s symptoms of altered mental status, cranial nerve palsy and pachymeningeal enhancements were initially attributed to chronic subdural hematoma, as prior cases with this entity have been thought to be causative. There was also some concern for lymphoma or other malignant processes, which have also shown similar MRI and clinical findings. However, our patient’s imaging was concerning for downward displacement of the brain, with smaller than expected ventricles and cisterns, and low opening pressure on lumbar puncture, all consistent with a diagnosis of spontaneous intracranial hypotension (Figs. 1, 2) SIH is an uncommon phenomenon, occurring at an incidence of 5 per 100,000 people per year, most often in the fourth and fifth decade, with women affected more than men in a 2:1 ratio. SIH is classically described as presenting with a postural headache associated with meningeal signs [1, 2]. The proposed etiology is a CSF leak through a spontaneous dural defect, frequently in the spine at the cervico-thoracic junction or thoracic regions. SIH symptomatology is typically described as a postural headache with meningeal signs, vertigo, hearing loss, and diplopia . However, it can have heterogeneous presentations, including cranial nerve palsies, cortical vein and sinus thromboses, depressed mental status, weakness, ataxia, bulbar weakness, postural tremor, chorea, vasoconstriction, galactorrhea, radiculopathy, and myelopathy . Changes in hearing, vertigo and dizziness are thought to be from vestibulocochlear nerve deformation and low perilymphatic pressure . Cranial neuropathies, pituitary dysfunction, and brain stem signs are thought to be secondary to brain sagging, which generates downward pressure. More severe pressure may be associated with ataxia, bulbar signs, parkinsonism, and chorea. Radiculopathy and myelopathy are thought to be secondary to local CSF collections .
Intracranial imaging findings of SIH include brain sagging, pachymeningeal enhancement, venous engorgement, enlarged pituitary and subdural collections, with or without hemorrhage from stretching of bridging veins . Spinal imaging may reveal distended epidural veins, epidural fluid collections, abnormal nerve root visualization, and meningeal diverticula. CSF leakage site may be detected with either CT or MRI myelography, both of which involve injection of contrast into the epidural space to look for contrast extravasations . Treatment options range from conservative measures such as bed rest, hydration and caffeine to epidural blood patch, epidural fibrin patch, and targeted blood/fibrin patch. These measures are curative in about 75 % of cases . In refractory cases, surgery with meningeal suturing or epidural packing may be attempted. Intrathecal saline injection to restore CSF volume until leak is repaired may be warranted in cases of depressed mental status . However, there are no consensus guidelines on surgical intervention for subdural collections .
Spontaneous intracranial hypotension (SIH) is an uncommon but often serious illness that may result in diverse clinical presentations. Unique imaging findings, including brain sagging, subdural collections, and pachymeningeal enhancement should raise concern for the presence of SIH. The use of Trendelenburg positioning for greater than 24 h to assess improvement may be used in evaluation of such cases. When the concern for SIH is high, prompt CT or MRI myelography should be used to confirm diagnosis and guide treatment. A variety of treatment options exist and may provide definitive cure.
AC Berry is the article guarantor. No financial support was obtained for the project. No financial grant was obtained. None of the authors listed received any financial support or services or any other contributions for their work. All patient identifiers have been removed.
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The authors declare that they have no conflict of interest.
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All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.
As with all case reports from my institution, waiver of informed consent was granted by the IRB.