Real-life study of the use of oto-acoustic emissions in the diagnosis of intracranial hypotension

BACKGROUND

The diagnosis of spontaneous or post-traumatic intracranial hypotension (IH) mainly relies on clinical features and neuro-imaging. However, the results of brain and spine magnetic resonance imaging are not always contributive. There is an interest for other non-invasive procedures, able to confirm or refute the diagnosis. The use of oto-acoustic emissions (OAE) was previously reported on isolated cases of IH associated with endolymphatic hydrops (ELH). The aim of this study was to assess the real-life utilization of this electrophysiological method in a larger population of suspected IH.

METHODS

A retro-prospective cohort study was conducted from November 2013 to July 2022 in patients with a suspected or doubtful diagnosis of IH. They were assessed for ELH by recording bilateral distortion product of oto-acoustic emissions (DPOAE) in sitting then in supine position.

RESULTS

Among the 32 patients assessed, the diagnostic of IH was confirmed in 18 patients. An ELH was shown in 15 of them (83%), but also in seven other patients. They had several differential diagnoses: chronic migraine, Chiari malformation, rebound intracranial hypertension and perilymph fistula.

CONCLUSIONS

This procedure seems to be insufficient to exclude differential diagnosis when intracranial hypotension is suspected.

Atypical Presentations of Intracranial Hypotension: Comparison with Classic Spontaneous Intracranial Hypotension

BACKGROUND AND PURPOSE

Atypical clinical presentations of spontaneous intracranial hypotension include obtundation, memory deficits, dementia with frontotemporal features, parkinsonism, and ataxia. The purpose of this study was to compare clinical and imaging features of spontaneous intracranial hypotension with typical-versus-atypical presentations.

MATERIALS AND METHODS

Clinical records and neuroimaging of patients with spontaneous intracranial hypotension from September 2005 to August 2014 were retrospectively evaluated. Patients with classic spontaneous intracranial hypotension (n = 33; mean age, 41.7 ± 14.3 years) were compared with those with intracranial hypotension with atypical clinical presentation (n = 8; mean age, 55.9 ± 14.1 years) and 36 controls (mean age, 41.4 ± 11.2 years).

RESULTS

Patients with atypical spontaneous intracranial hypotension were older than those with classic spontaneous intracranial hypotension (55.9 ± 14.1 years versus 41.7 ± 14.3 years; P = .018). Symptom duration was shorter in classic compared with atypical spontaneous intracranial hypotension (3.78 ± 7.18 months versus 21.93 ± 18.43 months; P = .015). There was no significant difference in dural enhancement, subdural hematomas, or cerebellar tonsil herniation. Patients with atypical spontaneous intracranial hypotension had significantly more elongated anteroposterior midbrain diameter compared with those with classic spontaneous intracranial hypotension (33.6 ± 2.9 mm versus 27.3 ± 2.9 mm; P < .001) and shortened pontomammillary distance (2.8 ± 1 mm versus 5.15 ± 1.5 mm; P < .001). Patients with atypical spontaneous intracranial hypotension were less likely to become symptom-free, regardless of treatment, compared with those with classic spontaneous intracranial hypotension (χ(2) = 13.99, P < .001).

CONCLUSIONS

In this sample of 8 patients, atypical spontaneous intracranial hypotension was a more chronic syndrome compared with classic spontaneous intracranial hypotension, with more severe brain sagging, lower rates of clinical response, and frequent relapses. Awareness of atypical presentations of spontaneous intracranial hypotension is paramount.

Subdural Haematoma in Patients With Spontaneous Intracranial Hypotension

The incidence and clinical relevance of subdural haematoma (SDH) in patients with spontaneous intracranial hypotension (SIH) remain undetermined. We reviewed 40 consecutive SIH patients (18 female, 22 male) in a tertiary hospital. Eight (20%) of them had SDH and nine (23%), non-haemorrhagic subdural collections. The presence of SDH was associated with higher frequencies of male gender, recurrence of severe headache and neurological deficits. Outcomes were satisfactory after supportive care or epidural blood patches except for one SDH patient, who developed transtentorial herniation resulting in Duret haemorrhage and infarctions of bilateral posterior cerebral artery territories. In conclusion, subdural fluid collections were common in patients with SIH. SDH was associated with headache worsening or neurological deficits. Patients with SDH generally recovered well; however, serious sequela might occur.

Pathophysiology and management of spontaneous intracranial hypotension--a review

Spontaneous Intracranial Hypotension is a syndrome involving reduced intracranial pressure secondary to a dural tear which occurs mostly due to connective tissue disorders such as Marfans Syndrome, and Ehler Danlos Syndrome. Patients with dural ectasias leading to CSF leakage into the subdural or epidural space classically present with orthostatic headaches and cranial nerve deficits mostly seen in cranial nerves V-VIII. Diagnosis of SIH is confirmed with the aid of neuroimaging modalities of which Cranial MR imaging is most widely used. SIH can be treated conservatively or with epidural blood patches which are now widely being used to repair dural tears, and their effectiveness is being recognized. Recently epidural injection of fibrin glue has also been used which has been found to be effective in certain patients.

[Intracranial hypotension syndrome: a review of the magnetic resonance findings]

INTRODUCTION

Intracranial hypotension syndrome (IHS) is a syndrome with a variable aetiology and clinical presentation that is, in most cases, caused by leakage of cerebrospinal fluid (CSF) through the thecal sac. Orthostatic headache associated to the typical magnetic resonance imaging (MRI) findings, secondary to depletion of CSF, is the key to a correct diagnosis.

AIMS

To show the imaging findings that, within a suitable clinical context, allow this condition to be identified and diagnosed.

DEVELOPMENT

Decreased CSF volume plays an important role in IHS, which leads to an increase in the compensatory volume of blood, essentially dependent on the venous system. MRI is a sensitive technique in the diagnosis of IHS. Yet, separate findings are unspecific. The MRI findings include diffuse and homogeneous dural enhancement, the presence of small bilateral subdural collections, caudal displacement of the encephalic structures (pseudo-Chiari), dilatation of the cortical and medullar veins, and the recent sign of venous distension. This last sign is a highly sensitive finding of IHS, which tends to disappear following the patient's clinical improvement even before the disappearance of the pachy-meningeal enhancement, and could be used as a marker for response to treatment.

CONCLUSIONS

IHS is a condition that is difficult to diagnose clinically for which several typical MRI findings have been reported; both neurologists and radiologists must be familiar with these findings.

[Severe intracranial hypotension in an adolescent with Marfan syndrome. Case report]

Spontaneous intracranial hypotension is a rare complication of connective tissue disorders. One of them is Marfan syndrome. It predisposes the patient to meningeal diverticula. Possibly after minor unrecognised head trauma or secondary to Valsalva manoeuvre cerebrospinal fluid leak from meningeal diverticula can happen. It causes postural headache. We describe a 15 year old adolescent female newly diagnosed with Marfan syndrome, who presented with intractable postural headache. Our patient's brain MRI showed bilateral frontal subdural effusion, narrow ventricles, downward displacement of the brainstem, enlarged cervical venous plexi, dural ectasias and wide nerve root sleeves. Radionuclide cisternography demonstrated CSF leaks at multiple sites. She could not be treated conservatively, but was successfully treated by epidural saline injections. Control brain and cervical MRI confirmed her healing, too. At the two and half year follow up visit, she was completely well. So we recommend this easy technique to be used before epidural autologous blood patches.

Relative decrease in signal intensity of subcortical white matter in spontaneous intracranial hypotension on fluid-attenuated inversion recovery images

BACKGROUND AND PURPOSE

In reviewing MR images of patients with spontaneous intracranial hypotension (SIH), we found an accentuated decrease in the subcortical white matter on fluid-attenuated inversion recovery (FLAIR) images. Our aim was to determine whether the signal intensity of the subcortical white matter decreases on FLAIR and T2-weighted images in SIH.

MATERIALS AND METHODS

We retrospectively examined pretreatment MR images including 7 FLAIR and 10 T2-weighted images obtained from 10 patients with SIH and follow-up images (5 FLAIR and 7 T2-weighted images). Two observers measured the signal intensities in the subcortical white matter on MR images at the level of the centrum semiovale and, to calculate the signal intensity ratios, measured those of the adjacent cortex and corpus callosum. Furthermore, 4 observers performed visual evaluation for accentuated signal intensity decreases for receiver operating characteristic (ROC) analysis.

RESULTS

The intensity ratios of the subcortical white matter, both to the adjacent cortex and corpus callosum, were significantly different between the control and pretreatment images in SIH and between pretreatment and follow-up images in SIH on FLAIR images, whereas these showed no significant differences between the control and follow-up images in SIH. On visual inspection, an accentuated decrease in signal intensity in the subcortical white matter was shown on pretreatment FLAIR images, which returned to the control level on follow-up images. However, on the T2-weighted images we could hardly recognize the decrease in the signal intensity.

CONCLUSIONS

Awareness of the decreased signal intensity of the subcortical white matter on FLAIR images could help in the diagnosis of SIH.

Intracranial hypotension following scoliosis surgery: dural penetration of a thoracic pedicle screw

The authors report on a 14 years old female with intracranial hypotension who had a history of spinal instrumentation surgery for scoliosis 3 months prior to her admission. She had been diagnosed with migraine in a neurology clinic and was under medical therapy when presented. During the investigation process, a right thoracic pedicle screw, which was penetrating and transversing the dura mater at the T3-T4 level was identified. The diagnosis and management of such a case is discussed. Knowledge of this entity is of extreme importance to spine surgeons, in order to prevent delayed diagnosis and possible complications.

[Spontaneous intracranial hypotension--a case report and discussion]

Thirty-three year old woman came to the emergency room with 3 days' history of worsening headache which was relieved by lying down. Examination was normal. Magnetic Resonance Imaging (MRI) of the head showed an enhancement of the meninges. No pressure could be measured during lumbar puncture and cerebrospinal fluid (CSF) was obtained by elevating the patient's head. There was an elevation of protein in the CSF without signs of infection or inflammation. Computerised tomography (CT) myelogram showed a prominent leak from the 2nd right cervical nerve sheath. A blood patch was done at this level with some improvement of symptoms. The patient was readmitted four days later as the headache had worsened. A blood patch was repeated at the same level with limited results. Therefore a fibrinogen patch was done at the same level, of which the effect lasted only 24 hours. A repeated CT myelogram showed a leak from the left 8th cervical and 1st thoracic nerve sheets, but not from the 2nd right cervical nerve sheath. Blood and fibrinogen patches were done at these levels repeatedly with limited results. Therefore, a MRI of cervical-thoracic spine was done which showed signs of previous blood patch at the 1st left thoracic nerve sheath but no sign of a patch over the 8th left cervical nerve sheath. A fibrinogen patch was done at this level. The patient became symptom free and was finally discharged home. We present a case of complicated spontaneous intracranial hypotension and review of the literature.

Spontaneous intracranial hypotension with deep brain swelling

Spontaneous intracranial hypotension (SIH) is caused by leakage of CSF, and characterized on MRI by brain sagging, dilatation of veins and dural sinuses, subdural fluid collections and post-contrast enhancement of the thickened dura. A few cases may present a very severe brain sagging through the tentorial notch and swelling of the diencephalic-mesencephalic structures, with absent or scarce subdural collections and post-contrast enhancement. These patients may have surprisingly few neurological signs or may become drowsy and even lapse into coma due to central herniation. We retrospectively examined the diffusion studies obtained in five patients with these MRI findings, in seven patients with SIH without brain swellings and in ten controls. Mean diffusivity was increased in SIH patients with brain swelling in areas draining into the deep venous system, collected by the vein of Galen (vG) and straight sinus (SS). In the hypothesis that central herniation might be responsible for venous stagnation because of impaired flow of the vG into the SS, the vG/SS angle was measured. The angle formed by the vG entering the SS was not altered in patients without brain swelling (group E, 67.8 degrees +/- 10.3 degrees, mean +/- SD, range 49-80 degrees) when compared to controls (group C, 73.3 degrees +/- 12.3 degrees, mean +/- SD, range 56-95 degrees). It was, however, grossly decreased in patients with brain swelling (group D, 40.7 degrees +/- 12.8 degrees, mean +/- SD, range 22-61 degrees), P < 0.001 for comparison with groups E and C. As suggested by previous studies, downward stretching of the vG and narrowing of the vG/SS angle may cause a functional stenosis at the vG-SS junction. We suggest that in the application of the Monro-Kellie doctrine to SIH, the brain volume should not be considered as always invariable.

Epidural venous engorgement resulting in progressive cervical myelopathy from shunt-related intracranial hypotension

The authors report an unusual case of engorged epidural veins causing progressive cervical myelopathy after long-term cerebrospinal fluid (CSF) shunt therapy and intracranial hypotension. An 18-year-old woman, who had previously undergone shunt placement with a distal slit valve for a porencephalic cyst when 2 years of age, presented with progressive spastic quadriparesis, numbness, and gait difficulty. Postural headaches were absent and a lumbar puncture revealed low CSF pressure. Neuroimaging disclosed markedly engorged anterior epidural veins causing compression of the cervical spinal cord. The slit-valve shunt system was surgically removed and an external drain was placed. The patient's CSF pressure was gradually raised to clinically tolerable levels. Once the optimal pressure was identified, a programmable shunt was placed with the valve set at the same level. The patient's neurological status improved, and the epidural veins had returned to their normal size on follow-up imaging. The authors describe the unique treatment strategy used in this patient and review the literature on epidural venous engorgement as it relates to intracranial hypotension.

Epidural dextran-40 and paramethasone injection for treatment of spontaneous intracranial hypotension

PURPOSE

This report describes treatment with epidural dextran-40 and paramethasone injection of postural headache resulting from spontaneous intracranial hypotension in a pregnant patient.

CLINICAL FEATURES

A 39-yr-old pregnant woman consulted the pain clinic for the assessment of a debilitating postural headache which was non-responsive to conventional analgesic treatment. Clinical findings and cranial magnetic resonance imaging indicated the diagnosis of spontaneous intracranial hypotension syndrome. Treatment with an epidural blood patch was not undertaken for several reasons. A lumbar epidural injection with dextran-40 and paramethasone led to a significant improvement in the symptoms and allowed a progressive discontinuation of adjuvant treatment with oral steroids, with complete resolution of symptoms.

CONCLUSION

We report a case of spontaneous intracranial hypotension in a pregnant patient successfully treated by epidural injection of dextran-40 and paramethasone, with adjuvant oral steroid therapy. Clinical trials are warranted to establish the efficacy of this treatment as an alternative to the epidural blood patch administration.

[Post-lumbar puncture syndrome--its pathogenesis, prophylaxis and treatment]

Post-lumbar puncture syndrome (PLPS) is a frequent and important complication of diagnostic lumbar puncture. PLPS is primarily caused by perforation of the dura mater, leading to persistent leak of the cerebrospinal fluid, and, as a result, intracranial hypotension. Effective therapeutic options are limited to symptomatic treatment until natural improvement occurs, or, in cases of prolonged complaints, invasive treatment (epidural blood patch with patient's own venous blood), which makes prophylaxis of PLPS essential. Prophylactic measures of confirmed efficacy are: reducing needle size, positioning the needle bevel parallel to the long axis of the spine, re-inserting the stilet before withdrawal of the needle, and, if possible, using a so-called "atraumatic" needle, minimizing the perforation of the meninx. The volume of the cerebrospinal fluid collected and the position of the patient after the procedure do not have a significant influence on PLPS frequency.

Cerebellar haemorrhage after non-traumatic evacuation of supratentorial chronic subdural haematoma: report of two cases

Cerebellar haemorrhage is an unusual complication of supratentorial neurosurgery. Several causative pre-operative factors and medical risk factors may predispose patients to cerebellar haemorrhage, however its etiology remains still unclear. Only two case reports have previously described the occurrence of cerebellar haemorrhage after subdural haematoma evacuation by burr-hole trepanation. We present two patients with this rare postoperative complication of minor supratentorial neurosurgery and possible underlying pathophysiological mechanisms are discussed. Our two cases support the post- rather than per-operative pathogenetic hypothesis. Although the complication is associated with a significant morbidity and mortality, most cases follow a benign course.

Rebound intracranial hypertension after treatment of spontaneous intracranial hypotension

Spontaneous intracranial hypotension (SIH) is characterized by orthostatic headache and the cause is usually cerebrospinal fluid leaks in spine level. Most patients with SIH have a benign course. Epidural blood patch (EBP) is the treatment of choice when initial conservative managements are ineffective. We reported a patient with SIH diagnosed by using magnetic resonance imaging and radionuclide cisternography. Acute rebound intracranial hypertension developed after EBP and was successfully treated with intravenous osmotic agent.

Thunderclap headache

Thunderclap headache (TCH) is head pain that begins suddenly and is severe at onset. TCH might be the first sign of subarachnoid haemorrhage, unruptured intracranial aneurysm, cerebral venous sinus thrombosis, cervical artery dissection, acute hypertensive crisis, spontaneous intracranial hypotension, ischaemic stroke, retroclival haematoma, pituitary apoplexy, third ventricle colloid cyst, and intracranial infection. Primary thunderclap headache is diagnosed when no underlying cause is discovered. Patients with TCH who have evidence of reversible, segmental, cerebral vasoconstriction of circle of Willis arteries and normal or near-normal results on cerebrospinal fluid assessment are thought to have reversible cerebral vasoconstriction syndrome. Herein, we discuss the differential diagnosis of TCH, diagnostic criteria for the primary disorder, and proper assessment of patients. We also offer pathophysiological considerations for primary TCH.

Dural sinus thrombosis in spontaneous intracranial hypotension

Dural sinus thrombosis (DST) is rarely associated with spontaneous intracranial hypotension (SIH). Engorgement of the venous system, caused by the CSF loss that occurs in SIH, is considered to favour the thrombosis, although signs of both SIH and DST are usually seen simultaneously at the first diagnostic MRI. We observed two patients with SIH and DST. Changes in pattern of headaches and MRI findings demonstrated that DST followed SIH. In SIH, the velocity of the blood flow in the dural sinuses may be reduced because of dilatation of the venous system which compensates the CSF loss. Other possible mechanisms seem unlikely on the grounds of both clinical presentation and MRI studies.

A case of spontaneous intracranial hypotension with typical magnetic resonance images

Spontaneous intracranial hypotension (SIH) is a rare syndrome defined by postural headache, associated with a low cerebrospinal fluid pressure, without history of previous dural trauma or invasive treatment on rachis. We reported a case of a patient with postural headache caused by SIH identified by magnetic resonance images and treated with saline solution infusion with complete remission of symptoms.

Spontaneous intracranial hypotension with pituitary adenoma

Spontaneous intracranial hypotension (SIH) is an unusual syndrome that is characterised by positional headache, neck rigidity, nausea and vomiting. The characteristic magnetic resonance imaging (MRI) findings are diffuse smooth pachymeningeal thickening and enhancement, downward displacement of posterior fossa structures and pituitary gland enlargement. An unusual case of SIH with pituitary macro-adenoma and subsequent subdural haemorrhage is presented, and its clinical picture, MRI findings and possible pathophysiological mechanism are discussed.

[Early subdural haematoma as the first symptom of intracranial hypotension syndrome: results from magnetic resonance imaging]

INTRODUCTION

Subdural haematoma associated to intracranial hypotension syndrome (IHS) is an infrequent complication. Its sudden early appearance in this female patient allowed us to diagnose and treat the syndrome at an early stage of development.

CASE REPORT

We describe the case of a 29-year-old patient who had a caesarean with spinal anaesthesia and, 48 hours afterwards, presented IHS accompanied by focal neurological symptoms as a consequence of a subdural haematoma. Performing an emergency computerised tomography scan and magnetic resonance imaging (MRI) at 14 hours allowed early diagnosis and treatment to be established.

CONCLUSIONS

MRI is essential to confirm the clinical suspicion of IHS and thus avoid the need to submit the patient to invasive tests. In this way, treatment for the IHS can be initiated at an early stage and the subdural haematoma can be resolved without the need for surgical drainage.

Rapid fluctuations in conscious state in a patient with an extensive spinal dural fistula

A man with a spontaneous spinal dural fistula and significant fluctuations in level of consciousness is discussed. The presentation was that of headache and vomiting followed by an initially enigmatic acute reduction in the level of consciousness. This required urgent evacuation of bilateral chronic subdural haematomas, believed to be causative. Following mobilisation, several episodes of presumed orthostatic intracranial hypotension occurred rendering the patient rapidly unconscious. A large spinal extradural CSF collection extending through the full length of the vertebral canal was later diagnosed however, the precise location of the fistulous leak could not be found radiologically. Non-operative management was successful. To the best of our knowledge, this is the first description of a spontaneous spinal cerebrospinal fluid leak of this magnitude. The case, pathogenesis, investigations and management of this rare entity are considered and the literature reviewed.

Thunderclap headache caused by spontaneous intracranial hypotension

We report a group of 4 patients with thunderclap headache as the initial manifestation of spontaneous intracranial hypotension.

[Posture-dependent headache due to the spontaneous hypotension syndrome]

A 40-year-old woman and a 47-year-old man presented with acute posture-dependent headache. A spontaneous intracranial hypotension syndrome was diagnosed in both cases. MRI with a gadolinium contrast medium revealed staining of the pachymeninges. In the woman, cisternography revealed leakage of spinal fluid at the level of the cauda equina. Neither an infusion of caffeine nor an epidural blood patch helped, but the symptoms disappeared spontaneously. In the man, cisternography indicated leakage at the level of the 3rd thoracic vertebra. The symptoms disappeared rapidly after treatment with a local blood patch. Posture-dependent headache is typical for the intracranial hypotension syndrome. The headache is usually relieved by lying down and aggravated by standing up, but the reverse has also been reported. This headache can develop in a short time, sometimes acutely, and may persist continuously. The syndrome is usually caused by leakage of cerebrospinal fluid due to rupture of the dura mater, which may occur spontaneously. The diagnosis can be established by gadolinium MRI, revealing a striking pattern of diffuse pachymeningeal enhancement. Subdural fluid accumulations may also be seen. Indium-pentetreotide cisternography can often localise the spinal fluid leak. Intravenous caffeine and the application of an autologous epidural blood patch are possible treatment options, but spontaneous recovery may also occur.

Headache attributed to spontaneous low CSF pressure: report of three cases responsive to corticosteroids

The therapy of headache attributed to spontaneous low CSF pressure (previously defined as spontaneous intracranial hypotension) is still a matter of debate. Epidural blood patch is considered the most effective treatment. However, pharmacological strategies may be considered before blood patch. We report three patients with headache attributed to spontaneous low CSF pressure that were successfully treated with oral prednisone. Additional studies may be useful to prove the effectiveness of corticosteroids in this syndrome.

Headache and intracranial hypotension: neuroradiological findings

The cardinal and classic features of postural headache and low cerebrospinal fluid (CSF) pressure in intracranial hypotension may not dominate the clinical picture of the syndrome and may be associated with additional various neurological symptoms and signs. Reports of unusual clinical presentations continue to appear in the literature. Despite the considerable variability of the clinical spectrum, neuroradiological studies reveal more constant and characteristic features. Brain MRI findings include intracranial pachymeningeal thickening and post-contrast enhancement, subdural fluid collections and downward displacement or "sagging" of the brain. Spinal MRI findings include collapse of the dural sac with a festooned appearance, intense epidural enhancement owing to dilatation of the epidural venous plexus, and possible epidural fluid collections. In fact, spinal studies may demonstrate CSF leakage from spinal dural defects, which are considered the most common cause of the syndrome. Myelo-MR may suggest the possible point of CSF leakage, by demonstrating an irregular root sleeve; myelo-CT and radioisotope myelocisternography (RMC) are often needed to confirm the point of CSF leakage. Neuroimaging studies are, therefore, essential for suggesting and confirming the diagnosis.

Syringomyelia with Chiari malformation; 3 unusual cases with implications for pathogenesis

Syringomyelia is an important cause of neurological deficit. Most cases of non-traumatic syringomyelia occur in association with a Chiari malformation. We present three unusual examples of syringomyelia with such an association. The first case is that of syringomyelia in a young woman with Marfan's syndrome, a spontaneous CSF leak and intractable intracranial hypotension. The second is a woman with long-standing lumbo-peritoneal shunt for pseudotumour cerebri who developed an acquired Chiari malformation. A young woman with a Dandy-Walker cyst that herniated into the upper cervical canal is the third case. These cases provide a basis for discussion of the pathogenesis and management of syringomyelia and the Chiari malformation in such cases.

Spontaneous intracranial hypotension: morphological findings and CSF flow dynamics studied by MRI

We report on a case of spontaneous intracranial hypotension (SIH) presenting with classic MR findings, such as diffuse smooth thickening and intense contrast enhancement of the dura matter, increased size of the pituitary gland and downward displacement of the brain. In this case an engorgement of the cavernous sinuses is reported as an additional imaging finding of SIH. Moreover, phase-contrast MR study of the CSF flow dynamics revealed at the level of the aqueduct a decrease of the systolic and diastolic flow volume of CSF. A normalization of the flow volume was observed when SIH subsided.

[Spontaneous intracranial hypotension]

BACKGROUND

Spontaneous intracranial hypotension is probably an under-reported cause of headache and other neurological symptoms.

MATERIAL AND METHODS

We report six patients with this diagnosis and review the most recent literature on the topic.

RESULTS AND INTERPRETATION

Spontaneous intracranial hypotension is typically manifested by orthostatic headache and low opening pressure on lumbar puncture, but atypical presentations are frequently reported. Various imaging techniques may be helpful in establishing the diagnosis, and sometimes the precise point of leakage can be demonstrated. All our six patients had orthostatic headache; five had additional complaints. In four patients the diagnosis was verified by typical meningeal enhancement on brain magnetic resonance imaging, and in one patient computed tomographic myelography precisely revealed the leakage point. All six patients experienced relief of symptoms after conservative treatment. Spontaneous intracranial hypotension is a relatively benign syndrome, but it may be complicated by subdural haematomas. Connective tissue disorders may predispose for the condition.