Recently, intrathecal gadolinium-enhanced magnetic resonance (MR) myelography, has been shown to be comparable to radioisotope cisternography (RC) to detect the CSF leak. Table 1: Clinical features of SIH with imaging correlatesĬomputed tomography (CT) myelography is considered the most reliable imaging technique for localizing the actual site of CSF leak. Though postural headache is a hallmark, non-orthostatic headache, vomiting, neck stiffness and atypical presentations such as dementia, Parkinsonism More Details, and coma have been described. The typical clinical setting is of a young to middle-aged woman with new onset daily headache which is relived by lying down. The reported prevalence of SIH is 1 per 50 000, most commonly occurs in the 4 th to 5 th decade and is more frequent in females (M:F=1:2). įigure 1: Pathophysiology of SIH giving rise to various clinical manifestations Cascade of events and compensatory mechanisms leading to varied manifestations of SIH are illustrated in. Headache occurs due to stretching of pain-sensitive intracranial structures due to brain descent which is more in the standing position and due to venous engorgement to compensate for the lost CSF as per Monro-Kellie doctrine. CSF hypovolemia and hypotension (<60 mm H 2O) results in the descent of brain. , Approximately 10% of the estimated total CSF volume has to be reduced to induce orthostatic headache. , ĬSF hypovolemia plays a major part in the development of SIH as compared to CSF hypotension as many patients may have normal CSF pressure despite having typical symptoms of SIH. , Connective tissue disorders such as Marfan syndrome and Ehlers-Danlos syndrome More Details have been associated with SIH. However, lumbar puncture, spinal surgery, trauma, intercourse, sneezing or even bending down can be the triggering events. It generally occurs due to spontaneous dural tear. SIH, also known as "CSF hypovolemia syndrome" or "spontaneous spinal CSF leak", was first described by Schaltenbrand in 1938 who coined the term "Aliquorrhea". Pathophysiological basis of the clinical and imaging features has also been reviewed. The aim of this article is to review the definitions, clinical and imaging characteristics of both idiopathic intracranial hypertension (IIH) and spontaneous intracranial hypotension (SIH). Both the disorders have distinct clinical and imaging characteristics with many overlapping features and present a diagnostic challenge for the physician. Though not uncommon in clinical practice, both the entities are largely under or misdiagnosed. Two extremes of intracranial pressure (ICP) variations are intracranial hypertension and hypotension. Spontaneous intracranial hypo and hypertensions: An imaging review. How to cite this URL: Vaghela V, Hingwala DR, Kapilamoorthy TR, Kesavadas C, Thomas B. How to cite this article: Vaghela V, Hingwala DR, Kapilamoorthy TR, Kesavadas C, Thomas B. Keywords: Idiopathic intracranial hypertension, optic nerve sheath distension, optic nerve tortuosity, orthostatic headache, posterior globe flattening, spontaneous intracranial hypotension Careful observation of these findings may help in early accurate diagnosis and to provide appropriate early treatment. In this review, we attempt to compile the salient magnetic resonance imaging findings in these two conditions. As the clinical presentation is varied, imaging may also help the clinician in arriving at the diagnosis of IIH with the help of a few specific signs. Neuroimaging plays an important role in excluding secondary causes of raised intracranial tension. Idiopathic intracranial hypertension (IIH) is a syndrome of elevated intracranial tension without hydrocephalus or mass lesions and with normal CSF composition. Spontaneous intracranial hypotension occurs due to reduced CSF pressure usually as a result of a spontaneous dural tear. The idiopathic forms are largely under or misdiagnosed. Cerebrospinal fluid (CSF) pressure changes can manifest as either intracranial hypertension or hypotension.
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