Ans. is 'a' i.e., Increased intracranial tensionWe are not sure of the answer.We have gone for increased intracranial tension because spontaneous C.S.F. leak is associated with intracranial hypotension.Increased intracranial tension is not associated with spontaneous C.S.F. leak.All other options mentioned in the question are associated with spontaneous C.S.F. leak.Pseudotumor CerebriPseudotumor cerebri usually presents with triad of headache, papilledema and minimal or absent focal neurological signs, but rarely the presenting feature may be a nasal C.S.F. leak.Empty sella syndromeIn empty sella syndrome, the sella turcica (the bony structure which contains pituitary enlarges). In this disease there is a defect in tissue barrier that normally keeps the cerebrospinal fluid around the brain separate from the sella turcica. As a result cerebrospinal fluid puts increased pressure on the pituitary glands and the walls of the sella turcica. The sella tunica enlarges and the pituitary shrinks.The empty sella syndrome may produce no symptoms at all and seldom produces serious symptom. About half of those affected have headaches. In rare cases there is leaking of the cerebrospinal fluid from the nose.EncephaloceleEncephalocele may present with C.S.F. leak.More on spontaneous C.S.F. leak or spontaneous intracranial hypotensionSpontaneous intracranial hypotension is a condition where patient gets postural headache due to leak of the cerebrospinal fluid in the spinal membrane.What happens is that the leak causes low C.S.F. pressure within the nervous system and thus causes a string of headache to the patient.The problem with SIH is that it is hard to diagnose and there is not a great deal of information on why it occurs.It has been associated with connective tissue diseases which may involve the dura causing tear in it.To summarize it, spontaneous C.S.F. leak is very rare and unlike other causes it does not occur due to any specific traumatic event or surgical procedure in the nervous system.Although there is not much information on the possible causes of C.S.F. leak, it is suspected that an intrinsic weakness of the spinal membrane or an abnormality of the brain structure causes the rare condition. The symptoms of SIH are so small and so common that it can often be misdiagnosed.