Abstract
It is important to suspect intracranial hypotension based on distinctly frequent orthostatic headaches and diffuse dural hyperplasia. Lumbar puncture is a procedure prone to complications, especially in patients with already existing intracranial hypotension.
Keywords: contrast‐enhanced magnetic resonance imaging, diffuse dural thickening, intracranial hypotension, orthostatic headache, subdural hematoma
1. CASE
A 56‐year‐old man presented with a 5‐day history of tinnitus and orthostatic headache. We observed his difficulty in hearing and directional nystagmus. No abnormalities were evident on brain noncontrast computed tomography (CT). Due to diffuse dura mater thickening revealed by contrast‐enhanced magnetic resonance imaging (MRI) (Figure 1), he was admitted with a suspicion of spontaneous intracranial hypotension (SIH) or hypertrophic pachymeningitis. He had no history of head trauma or signs of autoimmune disease and had normal IgG4 levels. He was diagnosed with SIH given his cerebrospinal fluid (CSF) pressure of 0 mm Hg, as determined by multiple lumbar punctures. His headache, nystagmus, and tinnitus slightly improved after rehydration and rest, but persisted after the therapy. He complained of new‐onset headache 2 weeks after the lumbar punctures and mildly depressed consciousness level. Bilateral subdural hematoma and exacerbated dural thickening were observed on CT and contrast‐enhanced cranial MRI (Figure 2).
FIGURE 1.
Diffuse dural thickening on contrast‐enhanced magnetic resonance imaging/T1 imaging. (A) Horizontal section. (B) Coronal section
FIGURE 2.
(A) Magnetic resonance imaging (MRI)/fluid‐attenuated inversion recovery shows bilateral subdural hematoma. (B) Dural thickening with contrast enhancement is more prominent on contrast‐enhanced MRI/T1 imaging
Spontaneous intracranial hypotension, which causes CSF decrease due to CSF leak from the cerebrospinal cavity to the epidural space, is a rare disease (5 in 100 000) and generally occurs around age 40. Its symptoms, including headache, neck pain, dizziness, visual impairment, hearing changes, and nausea, may be triggered by cranial nerve traction associated with low CSF pressure. 1
Twenty percent of patients with SIH develop chronic subdural hematoma (CSDH) complications. 1 Chronic subdural hematoma is caused by subdural rupture of the bridging veins that are stretched as the cerebral parenchyma is pulled down due to low CSF pressure. Subdural hematoma after lumbar puncture is rare and the known risk factors include multiple punctures, puncture with a thick needle, coagulation disorders, and dehydration. 2 Additionally, lumbar puncture under a low CSF pressure has been proven to increase subdural hematoma risk due to further reduction of CSF pressure. 3 , 4
Low CSF pressure (commonly responsive to conservative treatments) may require surgery or lead to a fatal course if subdural hematoma is involved. 1 Therefore, noninvasive diagnostic imaging is crucial in diagnosing low CSF pressure in patients with headaches.
Intracranial hypotension shows diffuse dural imaging on contrast‐enhanced MRI, subdural hygroma, epidural venous plexus expansion, descent of the cerebellar tonsils, flattening of the brain stem, and pituitary enlargement. Diffuse dural thickening is particularly a critical observation, with a specificity of 93.0% (95% confidence interval (CI) [79.9‐98.2]) and a positive predictive value of 91.2% (95% CI [75.2‐97.7]), and is useful for diagnosis. 5
It is important to suspect intracranial hypotension based on distinctly frequent orthostatic headaches, and contrast‐enhanced MRI should be considered before lumbar puncture.
Lumbar puncture, especially when low CSF pressure is suspected from diffuse dural hyperplasia, should be performed carefully with a fine needle to avoid fatal complications of subdural hematoma. Conservative treatment options, such as replacement fluid without lumbar puncture, may be considered when there are many risk factors for subdural hematoma. Moreover, a subdural hematoma should be examined with imaging tests if a patient with low CSF pressure complains of a nonorthostatic headache.
CONFLICT OF INTEREST
The authors have stated explicitly that there are no conflicts of interest in connection with this article.
INFORMED CONSENT
We have obtained the consent of the patient for publication.
ACKNOWLEDGEMENTS
The authors would like to thank Editage (https://www.editage.jp/) for the English language review.
Hori H, Yoshihara H, Fukuchi T, Sugawara H. Importance of actively suspecting intracranial hypotension with diagnostic imaging prior to lumbar puncture. J Gen Fam Med. 2020;21:195–196. 10.1002/jgf2.329
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