spontaneous intracranial hypotension ( sih ) is characterized by postural headaches secondary to low csf pressures , which are not attributable to lumbar puncture ( lp ) , trauma , surgery or any other inciting event . sih is typically due to spontaneous spinal csf leaks , and are an important and often misdiagnosed cause of new onset headache in young and middleaged individuals , especially women . this is a case of a 31yearold female with no significant past medical history , and no history of oral contraceptive use , who came to the emergency department complaining of sudden onset intense 10/10 frontal headache worsened by sitting upright and/or standing , and alleviated by lying supine , associated with nausea and vomiting . on exam , vital signs were found to be blood pressure 101/70 mmhg , heart rate 61/min , respiratory rate 20/min , and temperature 98.7f . laboratory findings were found to be as follows : hb 14.3 g / dl , hct 42.3% , wbc 9.5 k/l , plt 297 k/l , glucose 91 mg / dl , bun 15 mg / dl , cr 0.8 mg / dl , na 138 meq / l , k 4.4 meq / l , cl 101 meq / l , and co2 25 meq / l . the rest of the physical exam , including neurological exam , was within normal limits . this patient denies any history of lumbar puncture in the past . upon arrival to the emergency department , a lumbar puncture was offered to the patient ; however , she refused at that time . a ct scan of the head without contrast was done in the ed as well and showed no acute intracranial processes . the patient 's headache was being treated with fioricet as needed for pain scale 25/10 and with morphine 1 mg iv as needed for pain scale 710/10 . an mra was done to rule out the possibility of berry aneurysm , which was found to be unremarkable . an mri with and without contrast showed dilatation of the right transverse sinus ( figs . 1 and 2 ) and paucity of csf fluid in both optic nerve sheaths , compatible with intracranial hypotension . mri brain demonstrating mild dilatation of the dominant right transverse sinus , compatible with intracranial hypotension . mri brain this finding has been reported in the setting of intracranial hypotension . as the patient 's headache continued without any resolution unless the patient remained supine , a neurology consult was ordered , and the patient agreed to a lumbar puncture . the lumbar puncture was performed successfully under fluoroscopic guidance , which yielded an opening pressure of 0 mmh2o . based on the all the above findings the patient was diagnosed with spontaneous intracranial hypotension , and morphine was discontinued , and fioricet alone was continued . the patient greatly improved with fioricet and caffeine tablets . patient was discharged home with followup in an outpatient setting . while postural headaches attributable to spontaneous intracranial hypotension in the postlumbar puncture setting is quite frequent , idiopathic spontaneous intracranial hypotension is an uncommon , but important cause of new onset postural headache in the young to middleaged population , especially females 1 . whether idiopathic or iatrogenic , spontaneous intracranial hypotension is classically described as an orthostatic headache that worsens when the patient is sitting upright or standing and resides when lying flat 1 , 2 , and can be accompanied by a multitude of symptoms , including nausea , vomiting , anorexia , neck pain , dizziness , photophobia , etc . idiopathic spontaneous intracranial hypotension is usually caused by a persistent occult csf leak , which presents with a postural headache as the most prominent symptom 4 . recognizing idiopathic spontaneous intracranial hypotension in patients is essential and may prevent costly unnecessary procedures . a retrospective study done by schievink involving 18 patients with headache due to idiopathic intracranial hypotension demonstrated that 17 , or 94% , were incorrectly diagnosed with a diagnostic delay ranging from 4 days to 13 years 1 . diagnosis of idiopathic spontaneous intracranial hypotension is ideally obtained with mri of the head with gadolinium , which often shows diffuse meningeal enhancement , engorgement of the venous sinuses , subdural fluid collections , or descent of the cerebellar tonsils , often misdiagnosed as a chiari malformation [ 2 , 4,6 ] . the aforementioned imaging findings are explained using the monrokellie hypothesis which states that the relationship between intracranial pressure and csf volume , blood and brain tissue form a constant . when one of these variables is either increased or decreased , the other variables must compensate accordingly to maintain the constant pressure . it is important to note that these imaging findings are only significant in the correct clinical setting of a postural headache not attributable to any other cause . lumbar puncture with opening pressures is confirmatory in the diagnosis of spontaneous intracranial hypotension and are expected to be 060 mm h2o ( normal pressures range from 60 to 120 mm h2o ) 4 , however , it is important to note that lumbar puncture may worsen the patient 's symptoms by removing more csf and potentially causing another leak , leading to postlp iatrogenic intracranial hypotension related headache 4 . initial preferred management of idiopathic spontaneous intracranial hypotension is conservative treatment with bed rest , fluid replacement and caffeine , in the form of caffeine tablets and/or high caffeine dietary intake , which due to its vasoconstricive properties has proven to work well 4 , 5 , 6 . if conservative treatment is found to be ineffective , then a nonfocalized epidural blood patch may be placed . should this too prove to be ineffective , then a ct myelogram may be done to localize the leak and then corrected with a focal epidural blood patch 4 , 5 , 6 . nonetheless , idiopathic spontaneous intracranial hypotension is a manageable condition , which if approached correctly may relieve your patient of significant distress , sooner rather than later , and may avoid costly invasive procedures . while spontaneous intracranial hypotension is an uncommon diagnosis , misdiagnosis of it is quite commonplace and is often confused with migraine , chiari malformation , pseudotumor cerebrii or aneurysms , which subsequently leads to wrong and potentially harmful procedures including craniotomies and brain biopsies . it is therefore important that both the primary care physicians and the neurologists keep idiopathic sih in their list of differential diagnoses when treating a postural headache in order to relieve symptoms in a quick and efficient manner as well as to avoid costly and invasive procedures .
key clinical messageheadache is one of the most common clinical entities , and has a long list of differential diagnoses ; however , one of the more uncommon causes of postural headache is spontaneous intracranial hypotension . 
 it is important that clinicians be aware of this condition , as it is often overlooked , leading to invasive and unnecessary diagnostic testing . a good history and physical exam , paired with an mri of the brain is sufficient to make the diagnosis of sih , relieve the symptomology of the patient in a quick and efficient manner , and avoid costly invasive procedures .