1). The term “SIH” no longer appears broad enough to embrace all these variations. Therefore, terms such as “CSF hypovolemia” or “CSF volume depletion” as well as “spontaneous CSF leaks” have appeared in the literature and have been used interchangeably.[6, 14, 15] This review article attempts to outline the broad clinical Microbiology inhibitor spectrum of this disorder including substantial headache variability as well as diagnostic approaches and imaging findings including the mechanisms of

these findings, etiologic considerations, the treatment options, and expectations from these treatments, as well as various complications in spontaneous CSF leaks. The etiologies of CSF volume depletion are listed in Table 1. The effect of total body water loss (true hypovolemic state) and the role of various types of trauma (eg, cranial, spinal, or sinus surgeries) as well as the impact of CSF shunt overdrainage would seem essentially obvious. However, the most challenging remains the etiology of the spontaneous group, which needs to be addressed in greater depth. More often than not, the exact cause of spontaneous CSF leaks remains undetermined. Nonetheless, significant minorities of patients display clinical or imaging features suggestive of the presence of a disorder of the connective tissue matrix. The evidence for a preexisting dural sac weakness

has been mTOR inhibitor increasingly recognized. Many patients have joint hypermobility or have ectatic dural sacs (especially in lumbar and low thoracic regions), multiple meningeal diverticula, or dilated nerve root sleeves (Fig. 2). Dural sac ectasia, meningeal diverticula, and CSF leaks have been noted in Marfan’s syndrome,[16, 17] a known heritable disorder of connective tissue matrix involving elastin and fibrillin. Stigmata of heritable

connective tissue disorder, including but not limited to Marfanoid features, have been observed in a notable minority of the patients with spontaneous see more CSF leaks.[18, 19] Single or multiple meningeal diverticula, which are frequently noted in patients with spontaneous CSF leaks, are also seen in certain heritable disorders of connective tissue. Familial occurrence of spontaneous CSF leaks and meningeal diverticula in the setting of familial joint hypermobility and strong family history of aortic aneurysms[20] is yet further testimony to the role of heritable disorders of the connective tissue in causing dural weakness that can lead to CSF leak (Fig. 3). A trivial previous trauma such as coughing, pulling, pushing, and lifting is sometimes reported in a minority of the patients. It is not unlikely that a combination of a weak thecal sac and a trivial trauma, which normally would have been harmless, might have caused a “spontaneous” CSF leak in some of the patients. Less common in occurrence, a dural tear from a spondylotic spur[21, 22] or disc herniation[23] may cause CSF leaks.