**1. Introduction**

[15] Petzold A, Groves M, Leis AA, Scaravilli F, Stokic DS, Neuronal and glial cerebrospi‐ nal fluid protein biomarkers are elevated after west nile virus infection, Muscle

[16] Ostegaard C, Benfield T, Macrophage migration inhibitory factor in cerebrospinal fluid from patients wit central nervous system infection, Critical care 13 (2009)

[17] Crawford JR. Advances in pediatric neurovirology. Curr Neurol Neurosci Rep. 2010

Nerve 41 (2010) 42-49

32 Encephalitis

Mar;10(2):147-54

Although the syndrome of spontaneous intracranial hypotension (SIH) is not an infectious disease, it is commonly involved in the differential diagnoses of meningitis and encephalitis. It is a clinical (headache, fever, even neck stiffness) and laboratory (cerebrospinal fluid (CSF) abnormalities) challenge for the physician. Considering this syndrome especially under some settings and taking care of the charactestic imaging findings would contribute to the diagnosis. We believe in that the physicians who care with these central nervous system (CNS) infections should be aware of this syndrome. Some patients under the suspicion of encephalitis have the SIH that could be diagnosed by approaches described in this chapter.

Patients presenting with fever, headache, stiff neck, nausea, vomiting and some other neuro‐ logical signs suggesting meningeal irritation are always taken seriously and usually have a similar diagnostic algorithm. Differential diagnosis is usually based on the results of CSF analysis. In some cases, characteristics of the headache are the major factor determining the way to establish the diagnosis. Headache with a positional pattern, that occurs shortly after assuming an upright position and relieves by lying down, so called "orthostatic headache" is a distinctive symptom of SIH syndrome.

The spontaneous form of intracranial hypotension was first described by a German neurolo‐ gist Georg Schaltenbrand in 1938 [1]. He recognized that "aliquorrhea," or as subsequently named "hypoliquorrhoea" a deficiency in cerebrospinal fluid, could result in headaches pre‐ dominantly when upright. Since the introduction of magnetic resonance image (MRI) in dai‐ ly diagnostic use in the early 1990s, much has been learned about SIH.

All or essentially all SIH cases are related with a spontaneous spinal CSF leak mostly at the cervicothoracic junction or along the thoracic spine [2].

© 2013 Balkan and Ozaras; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

SIH is an important and relatively frequent cause of newly onset daily persistent posi‐ tional headaches in young and middle-aged individuals. Women are effected more fre‐ quently than men with a ratio of approximately 1.5/1. It is diagnosed about half as frequently as spontaneous subarachnoid hemorrhage and its incidence is estimated to be five per 100 000 [3].

**3. SIH and aseptic meningitis**

photophobia, and meningismus.

overlooked.

given below (Table 2).

38.9 oC, 38.2 oC and 38.5 oC.

viral meningoencephalitis or usually aseptic meningitis [5].

examination typically reveals signs of nuchal rigidity

Patients admitted with fever, headache and CSF findings revealing lymphocytic pleocytosis, elevated protein concentration and normal glucose levels are prone to be misdiagnosed as

Spontaneous Intracranial Hypotension: What An Infectious Disease Physician Should Know?

http://dx.doi.org/10.5772/53744

35

The clinical presentation of aseptic meningitis is generally nonspecific, with fever, headache, nausea and vomiting, occasionally accompanied by photophobia and a stiff neck. Physical

The syndrome of "aseptic meningitis" including differing etiologies and disorders, presents a diagnostic challenge to the clinician [6]. Although many infectious and nonin‐ fectious etiologies exist for this syndrome, viruses, especially nonpolio enteroviruses, are the most common (>85%) and most important agents encountered. Although seasonal variation is relative and not absolute, enteroviruses are most likely to be the cause of aseptic meningitis occurring during the summer or fall. The onset of symptoms is char‐ acteristically abrupt and typically includes headache, fever, nausea or vomiting, malaise,

Because the presenting signs and symptoms of enteroviral meningitis are not distinctive, tu‐ berculosis meningitis, herpes simplex encephalitis, HIV encephalitis and parameningeal in‐ fection that may mimic aseptic meningitis in their initial presentations must not be

SIH may mimic aseptic meningitis. The main features of aseptic meningitis and SIH cases are compared in a case series newly reported form Turkey [7]. Various clinical and laborato‐ ry features of 11 consecutive cases of SIH and 10 consecutive cases of aseptic meningitis are

All of the 11 patients with SIH reported that their headache was occurring or worsening within minutes or hours assuming the upright position and improving by lying down, de‐ fined as "orthostatic headache". All met the diagnostic criteria defined by International Headache Society. The median duration of sudden-onset orthostatic headache was 10 days, ranging between 1 to 30 days. Five cases (5/11) had a previous diagnosis of migraine be‐ cause of chronic headache. The newly onset orthostatic headache was throbbing and diffuse in all cases distributing from posterior neck (5/11), from frontal area (4/11), from left tempo‐ ral region (1/11) and from left parietal region (1/11) to the whole cranium. The typical posi‐ tional characteristics of the headache were noticed with further questioning of the patients.

Hearing changes, disturbed sense of balance, and nausea were noted in all patients. Posteri‐ or neck pain and vomiting were described in 9, tinnitus in 3 patients, and echoing in 1 case.

Stiff neck was detected in 5 patients, and fever (axillary; >37.3°C) in 7 patients. The highest

C, 38.3 <sup>o</sup>

C, 38.1 <sup>o</sup>

C, 38 <sup>o</sup> C,

temperatures of those with fever were measured as follows; 38.7 <sup>o</sup>

Eight of 11 cases had visual changes as blurring (5/11) and diplopia (5/11).

Throbbing headache occurring or worsening in upright position and improving after lying down, so called "orthostatic headache", low CSF pressure, and diffuse pachymeningeal en‐ hancement on brain magnetic resonance imaging (MRI) are the major features of the classic syndrome. Many other signs and symptoms may associate.
