Neurology -- Correspondence for Hong et al., 58 (8) 1285-1287

Correspondence published:

Reply to Letter to the Editor: N. L. Foster, M. Hong, G. V. Shah, R. S. Turner, K. M Adams (5 June 2002)

Spontaneous intracranial hypotension causing reversible frontotemporal dementia: Robert A. Fishman, William P. Dillon (5 June 2002)

Reply to Letter to the Editor 5 June 2002

N. L. Foster
University of Michigan Ann Arbor, MI,
M. Hong, G. V. Shah, R. S. Turner, K. M Adams
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Re: Reply to Letter to the Editor

nlfoster{at}umich.edu N. L. Foster, et al.

We thank Drs. Fishman and Dillon for their comments and the opportunity to provide further information about the evaluation and management of the patient we recently described [1]. Since submitting our report, we have re-examined the patient and confirmed the continued resolution of both headache and dementia, now for more than a year after prednisone was discontinued. Our patient's subsequent course supports the validity of our diagnosis and management. While we do not know if radiographic abnormalities have completely resolved, at this point additional studies in this patient are unnecessary.
Drs. Fishman and Dillon suggest that a dural biopsy was not needed. We disagree, particularly since SIH had not previously been reported to cause dementia or any cognitive disorders other than stupor and obtundation. While a meningeal biopsy may not be needed in patients with typical symptoms or a history suggesting a CSF leak, a number of other disorders should be considered in patients with dementia and meningeal enhancement including bacterial, viral and fungal infections, meningeal carcinomatosis, and neurosarcoidosis [2]. It is important to consider a broad differential diagnosis until cognitive changes due to SIH are better defined. In most reports, there is no description of mental status. We urge others to systematically record cognitive performance in SIH patients to determine if changes are unusual or a characteristic feature of this syndrome.
We appreciate the suggestion that contrast myelography, and spinal MR may reveal an abnormality not demonstrated by radioisotope cisternography. We agree these are useful diagnostic tests, particularly in cases that are refractory to treatment.
Our correspondents fault us for failing to use an intrathecal saline infusion or epidural blood patches. While these are reasonable alternative approaches, the prolonged recumbancy and cooperation that they require make them unfeasible for a patient like ours who had significant behavioral and cognitive impairments. Furthermore, multiple blood patches frequently are required, even when performed at the level of an identified CSF leak [3]. Further studies are needed to determine whether corticosteroids or closure of CSF leaks through surgical intervention or physical barriers such as epidural blood patches should be primary therapy for SIH.
References:
1. Hong M, Shah GV, Adams KM, Turner RS, Foster NL. Spontaneous intracranial hypotension causing reversible frontotemporal dementia. Neurology 2002;58:1285-1287.
2. Mokri B, Piepgras DG, Miller GM. Syndrome of orthostatic headaches and diffuse pachymeningeal gadolinium enhancement. Mayo Clin Proc 1997;72:400-413.
3. Sencakova D, Mokri B, McClelland RL. The efficacy of epidural blood patch in spontaneous CSF leaks. Neurology 2001;57:1921-1923.

Spontaneous intracranial hypotension causing reversible frontotemporal dementia 5 June 2002

Robert A. Fishman
University of California, San Francisco,
William P. Dillon
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Re: Spontaneous intracranial hypotension causing reversible frontotemporal dementia

aon{at}itsa.ucsf.edu Robert A. Fishman, et al.

The recent report by Hong et al. [1] describes a 66-year-old man with spontaneous intracranial hypotension (SIH) presenting with an 18-month progressive history of cognitive impairment and postural headaches. MR imaging revealed characteristic diffuse dural enhancement and a "sagging" brain with mid-brain effacement, incisural block, pontine flattening, and tonsillar displacement. A dural biopsy was performed (unnecessary in our view) and a normal radioisotope cisternogram was obtained (a test that is often normal in our experience). Regrettably, contrast myelography and spinal MR were not done, tests we find essential in identifying spinal arachnoid (Tarlov) cysts which commonly are the site of CSF leaks.
The authors treated the patient with prednisone over a 4-month period with gradual improvement but with only partial resolution of the sagging brain and dural enhancement.
We have reported two analogous cases of SIH [2, 3] presenting with stupor and obtundation who also had the brain MR features characteristic of SIH. In both cases, intrathecal lumbar saline infusion dramatically relieved the encephalopathy. Multiple blood patches were carried out in both patients, and in one case surgical closure of the arachnoid cyst proved necessary.
We recommend that patients with SIH should have spinal MR imaging and contrast myelography to search for arachnoid cysts or other fistulas that commonly underlie SIH, unless they have responded to epidural blood patches. Dural biopsies are not rewarding in patients with characteristic clinical and radiological features of SIH. While steroid therapy may be helpful, it does not treat the leak, which argues against its use as a primary therapy. Large volume lumbar epidural blood patches (25-40 ml as tolerated) are first therapy unless severe brain sagging and obtundation indicate a need for intrathecal saline infusion using preservative-free buffered normal saline prior to searching for the site of the leak. The patient's head and trunk should be lowered for at least 5 minutes immediately after the injection to allow the blood to move to upper spinal levels. Large subdural effusions may demand surgical drainage. Small effusions disappear when CSF volume is restored.
References:
1. Hong M, Shah GV, Adams KM, Turner RS, Foster NL. Spontaneous intracranial hypotension causing reversible frontotemporal dementia. Neurology 2002;58:1285-1287.
2. Pleasure SJ, Abosch A, Friedman J, Ko N, Barbaro N, Dillon W, Fishman RA, Poncelet AN. Spontaneous intracranial hypotension resulting in stupor caused by diencephalic compression. Neurology 1998;50:1854-1857.
3. Binder DK, McDermott MW, Dillon WP, Fishman RA, Berger MS, Schmidt MH. Intrathecal saline infusion in the treatment of obtundation associated with spontaneous intracranial hypotension. Neurosurgery (in press 2002).