Severe acute orthostatic headache: spontaneous intracranial hypotension (SIH)

Abstract

The most common cause of spontaneous intracranial hypotension headache is a cerebrospinal fluid (CSF) leakage, but the underlying mechanisms remain unknown. Intracranial hypotension is characterised by diffuse pachymeningeal enhancement on cranial MRI features, low CSF pressure and orthostatic headaches mostly caused by the dural puncture. We report a 31-year-old woman who presented to our services with reports of continuous severe bifrontal headache, which increased on sitting up and resolved on lying down. MRI of the cervical and lumbosacral spine showed signs of CSF leak; hence, patient was diagnosed with spontaneous intracranial hypotension headache. A CT-guided epidural blood patch was done at L4–5 with fibrin glue injected at the site of leak. The patient’s signs and symptoms improved after the procedure.

Background

Spontaneous intracranial hypotension (SIH) should be considered as a differential diagnosis of new daily persistent headache. This kind of headache becomes worse on standing relieved by a recumbent position in 10–15 min. SIH has a low cerebrospinal fluid (CSF) pressure and MRI gladonium enhanced shows a uniform pachymeningeal enhancement with no dural trauma.

Case presentation

A 31-year-old woman presented to our services with reports of continuous severe bifrontal orthostatic headache, which increased within seconds on sitting up and resolved within seconds on lying down. She had no history of head trauma. Her headache used to also worsen during the Valsalva manoeuvre. Patient had a history of lower segment Caesarean section surgery under spinal anaesthesia 10 months back in a different hospital, which was followed by Postdural puncture headache lasting for 7 days. Her current headache was associated with nausea and dizziness since last 15 days. Patient had no other cochlear–vestibular signs like tinnitus, ear fullness, distortion of sounds or hypoacusia, except for the associated dizziness. Her symptoms were of gradual onset, there were no focal neurological signs and no signs of meningeal irritation. Patient had no history of interscapular pain, transient diplopia, numbness or facial pain or dysgeusia. She described the headaches as an intense pressure-like sensation. Over-the-counter analgesics were ineffective.

Investigations

Haematological and biochemical blood investigations including full blood count, electrolytes, random blood glucose, liver and renal function tests, erythrocyte sedimentation rate and C reactive protein were normal. ECG was normal. A lumbar puncture showed a CSF opening pressure of 18 mm H2O and the CSF examination was normal. The biochemical, cytological and microbiological analysis of CSF was normal and there was no xanthochromia. MRI brain was suggestive of pachymeningeal thickening and enhancement along the cerebral convexities. MRI brain also showed dural venous engorgement seen as bulky cavernous sinuses and mildly dilated dural venous sinuses. Figure 1A, B coronal contrast-enhanced MRI brain images reveal pachymeningeal thickening and enhancement along bilateral cerebral convexities (1c). Postcontrast axial images at the level of cavernous sinuses reveal venous engorgement in venous sinuses and cavernous sinuses seen as mild enlargement (arrow) (1d). Sagittal MRI image shows mild tonsillar descent consistent with intracranial hypotension. (white arrow). MRI of lumbosacral spine revealed a CSF sleeve in epidural space from L3 (lumbar) to S2 (sacral) vertebral level with resultant flattening of anterior dura representing the site of leak. MRI of the cervical spine also showed fluid in the anterior epidural space from C7 (cervical) to D2 (dorsal) vertebral levels. These findings were suggestive of SIH due to CSF leak. figure 2A, B sagittal T2 fat suppressed imaging (FATSAT), T2W MRI spine images reveal a thin CSF sleeve in epidural space from L3 to S2 vertebral level (white arrow). Figure 2C sagittal MRI spine at cervicodorsal level reveals another epidural CSF sleeve (white arrow). Figure 2D, E axial sections of MRI spine show anterior epidural fluid collection, anterior to dura causing flattening of anterior dura (*). The patient was diagnosed with SIH headache, according to the updated diagnostic criteria revised by Schievink et al¹

Figure 1.

(A) Axial and (B) coronal contrast-enhanced MRI brain images reveal pachymeningeal thickening and enhancement along bilateral cerebral convexities. (C) Postcontrast axial images at the level of cavernous sinuses reveal venous engorgement in venous sinuses and cavernous sinuses seen as mild enlargement (arrow) (D) Sagittal MRI image shows mild tonsillar descent consistent with intracranial hypotension (white arrow).

Figure 2.

(A) and (B) Sagittal T2 FATSAT, T2W MRI spine images reveal a thin CSF sleeve in epidural space from L3 to S2 vertebral level (white arrow). (C) Sagittal MRI spine at cervico-dorsal level reveals another epidural CSF sleeve (white arrow). (D) and (E) Axial sections of MRI spine shows anterior epidural fluid collection, anterior to dura causing flattening of anterior dura (*).

Differential diagnosis

As the recognised clinical phenotype of spontaneous spinal CSF leak has broadened, so too has the differential diagnosis of the many signs and symptoms associated with this entity broadened. Possibilities of multiple differential diagnosis were considered; postural orthostatic tachycardia syndrome is perhaps the most common nonleak cause of headache that is triggered or worsened with upright posture. Orthostatic hypotension, which can be caused by autonomic failure, medication effect or serious hypovolemia but not spinal CSF leakage, is another reasonably common cause of orthostatic headache. Subarachnoid haemorrhage was also considered, but the CSF did not reveal any xanthochromia. The presence of signs of CSF leak on cervicodorsal spine MRI leads us to the diagnosis of SIH in our case.

Treatment

A course of intravenous dexamethasone was given for 1 week with bedrest, analgesia, adequate hydration and caffeine, which showed no benefit. Most patients tend to have sufficient recovery from conservative measures such as rest and hydration. When these measures fail, a trial of an epidural blood patch (EBP) is usually attempted. In view of failure of medical treatment, a CT-guided EBP was done at L4–5 with fibrin glue injected at the site of leak. Patient tolerated the procedure well and she started responding to treatment.

Outcome and follow-up

The patient’s signs and symptoms improved after the procedure. The patient experienced complete remission of symptoms and was then discharged. Follow-up was conducted 3 months after discharge, by which time the patient had experienced no recurrence of symptoms.

Discussion

Schaltenbrand in 1938 first described SIH and the MRI findings, which were later described in 1991.² The International classification of headache disorders: 2nd edition (ICDH) first published the diagnostic criteria for SIH, these criteria were mainly clinical and the most important being headache, which is positional.³ The other associated criteria being the total resolution of symptoms after EBP.³ The most important feature of SIH is headache, which improves on resuming recumbent posture. Some patients also report of acute onset of headache—thunder clap and are diagnosed as subarachnoid haemorrhage and also undergo angiography. SIH may be associated with nausea vomiting, photophobia and posterior neck pain or stiffness, diplopia, changes in hearing and vertigo are commonly caused by the stretching of oculomotor, cochlear and vestibular nerves. The diagnosis of SIH has to be thought of and it is important to have a strong clinical suspicion. A lumbar puncture is fairly diagnostic and CSF opening pressure in SIH will be less than 16 mm H2O (normal—65–195 mm H2O).¹ The diagnostic criteria consist of A, orthostatic headache; B, the presence of at least one of the following: low opening pressure (≤60 mm H2O), sustained improvement of symptoms after EBP, demonstration of an active spinal CSF leak, cranial MRI changes of intracranial hypotension (eg, brain sagging or pachymeningeal enhancement); C, no recent history of dural puncture and D, not attributable to another disorder.⁴ However, it must be noted that, as per recent ICDH—three criteria, dural puncture to measure CSF pressure directly is not necessary in patients with positive MRI signs of leakage such as dural enhancement with contrast.⁵

CSF may show elevated pleocytosis and elevated proteins. The MRI is the diagnostic modality of choice of the initial evaluation of SIH. The three most diagnostic imaging feature of SIH are enhancement of the pachymeningitis and downward displacement of brain (brain is sagging) and subdural collections. The pathognomonic findings on contrasted MRI brain are diffuse, smooth, pachymeningeal gadolinium enhancement (DPGE) and brain sagging. DPGE is typically due to the dilation of the dural veins secondary to negative pressure.⁶ The management of SIH starts from medical treatment, which is bedrest, intake of oral fluids and administration of glucocorticoids. Most patients do respond to medication. The clear-cut treatment of SIH is the placement of one or more epidural patches—10 to 15 mL of blood. Most patients like ours do very well but although some patients may have a relapsing or persistent symptoms and disability.

Learning points.

• Intracranial hypotension, especially spontaneous intracranial hypotension (SIH), is much more common than generally realised and poses considerable diagnostic and treatment challenges.

• The three most diagnostic imaging feature of SIH are enhancement of the pachymeningitis, downward displacement of brain (brain is sagging) and subdural collections.

• Autologous epidural blood patch may be administered intrathecally, which leads to sealing of the site of leakage with a formed clot.

Ethics statements

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