Brain Sagging Research Articles

Frontotemporal brain sagging syndrome

Behavioral variant frontotemporal dementia (bvFTD) is a relatively well-defined clinical syndrome. It is associated with frontal and temporal lobe structural/metabolic changes and pathologic findings of a neurodegenerative disease. We have been evaluating patients with clinical and imaging features partially consistent with bvFTD but with evidence also suggestive of brain sagging, which we refer to as frontotemporal brain sagging syndrome (FBSS). Retrospective medical chart review to identify all patients seen at our institution between 1996 and 2010, who had a clinical diagnosis of FTD and imaging evidence of brain sag. Eight patients, 7 male and 1 female, were diagnosed with FBSS. The median age at symptom onset was 53 years. All patients had insidious onset and slow progression of behavioral and cognitive dysfunction accompanied by daytime somnolence and headache. Of the 5 patients with functional imaging, all showed evidence of hypometabolism of the frontotemporal regions. On brain MRI, all patients had evidence of brain sagging with distortion of the brainstem; 3 patients had diffuse pachymeningeal enhancement. CSF opening pressure was varied and CSF protein was mildly elevated. A definite site of CSF leak was not identified by myelogram or cisternography, except in one patient with a site highly suggestive of leak who subsequently underwent surgery confirming a CSF leak. In 2 patients with a neuropathologic examination, there was no evidence of a neurodegenerative disease. This case series demonstrates that FBSS may mimic typical bvFTD but should be recognized as an unusual presentation that is potentially treatable.

Overt Cerebrospinal Fluid Drainage Is Not a Sine Qua Non for Paradoxical Herniation After Decompressive Craniectomy

Paradoxical transtentorial herniation is a rare but well-documented complication of cerebrospinal fluid (CSF) drainage in patients with large decompressive craniectomies. However, brain sagging in the absence of CSF hypovolemia has not been previously reported. A 30-year-old woman suffered massive intracerebral hemorrhage from a small residual left frontal arteriovenous malformation 1 year following endovascular embolization and stereotactic radiosurgery. The patient initially presented in coma with left mydriasis and decorticate posturing and underwent emergent decompressive craniectomy, evacuation of the hematoma, and insertion of an intracranial pressure (ICP) monitor. Postoperatively, despite a depressed skin flap and low ICP readings, she continued to deteriorate neurologically, and CT revealed increasing midline shift, transtentorial herniation, and brainstem compression. INTERVENTION OR TECHNIQUE: Although there was no history of CSF drainage, the diagnosis of brain sag was suspected, because herniation seemed to occur in the setting of intracranial hypotension. The patient was placed in a 15 degrees Trendelenburg position and improved dramatically within hours. A few days later, she was fully awake and had purposeful movements with her left side, although she had persistent aphasia and right hemiplegia. Although rare, paradoxical herniation in the setting of a large craniectomy defect may occur in the absence of CSF drainage. This entity should be suspected whenever transtentorial herniation occurs in conjunction with direct or indirect signs of intracranial hypotension. Placing the patient in the Trendelenburg position should be attempted, because this simple maneuver may turn out to be life-saving.

Coma from Worsening Spontaneous Intracranial Hypotension After Subdural Hematoma Evacuation

Low cerebrospinal fluid volume is typically diagnosed in patients presenting with positional headaches. However, severe intracranial hypotension and brain sagging may cause orthostatic coma. We present a case that illustrates this uncommon presentation. Case report. A 50-year-old man presented with orthostatic headaches and then developed bilateral subdural hematomas. Following unilateral subdural hematoma evacuation, the patient became gradually drowsier and more confused. Upon transfer to our hospital, he would become comatose each time he was placed in the upright position. Successful epidural patch at the level of a spontaneous cerebrospinal fluid leak documented by myelography resulted in complete resolution of his orthostatic symptoms despite reaccumulation of the subdural fluid collection. Evacuation of subdural fluid collections may be detrimental in patients with low CSF volume by exacerbating the intracranial hypotension. Extreme brain sagging may lead to anatomical distortion of the diencephalon and brainstem resulting in coma.

Isolated Cortical Venous Thrombosis Associated With Intracranial Hypotension Syndrome

The association of intracranial hypotension syndrome with cerebral venous thrombosis is rare. We report our experience with isolated cortical venous thrombosis, which developed after unsuccessful epidural anesthesia. Magnetic resonance imaging showed characteristic imaging findings of intracranial hypotension syndrome, such as dural thickening and brain sagging. We also detected right parietal venous hemorrhagic infarction secondary to right-sided cortical venous thrombosis. After the treatment of intracranial hypotension via epidural blood patch, heparin was used to treat cortical venous thrombosis.

Spontaneous spinal cerebrospinal fluid leak as a cause of coma after craniotomy for clipping of an unruptured intracranial aneurysm

Spontaneous spinal CSF leaks are best known as a cause of orthostatic headache, but may also be the cause of coma. The authors encountered a unique case of a spontaneous spinal CSF leak causing coma 2 days after craniotomy for clipping of an unruptured aneurysm. This 44-year-old woman with autosomal dominant polycystic kidney disease underwent an uneventful craniotomy for an incidental anterior choroidal artery aneurysm. No intraoperative spinal CSF drainage was used. Two days after surgery the patient became comatose with a left oculomotor nerve palsy. Computed tomography scanning revealed a right extraceberal hematoma and loss of gray-white matter differentiation. The hematoma was evacuated and a diagnosis of hemodialysis disequilibrium syndrome was made. Continuous hemodialysis and hyperosmolar therapy were instituted without any improvement. The CT scans were then reinterpreted as showing sagging of the brain, and the patient was placed in the Trendelenburg position which resulted in prompt improvement in her level of consciousness. A CT myelogram demonstrated an upper thoracic CSF leak that eventually required surgical correction. The patient made a complete neurological recovery. Neurological deterioration after craniotomy may be caused by brain sagging caused by a spontaneous spinal CSF leak, similar to intracranial hypotension due to intraoperative lumbar CSF drainage.

Spontaneous Spinal Cerebrospinal Fluid Leaks

Spontaneous intracranial hypotension is an uncommon but not rare cause of new onset daily persistent headaches. A delay in diagnosis is the norm. Women are affected more commonly than men and most are in the fifth or sixth decade of life. The underlying cause is a spontaneous spinal cerebrospinal fluid (CSF) leak. Typically the headache is orthostatic in nature but other headache patterns occur as well. Associated symptoms are common and include neck pain, a change in hearing, diplopia, facial numbness, cognitive abnormalities and even coma. Typical imaging findings consist of subdural fluid collections, pachymeningeal enhancement, pituitary hyperaemia and brain sagging, but magnetic resonance imaging may be normal. Myelography is the study of choice to identify the CSF leak but is not always necessary to make the diagnosis. Treatment consists of bedrest, abdominal binder, epidural blood patching, percutaneous fibrin glue injection or surgical CSF leak repair. Outcomes have been poorly studied.

Epidural Blood Patch for Severe Postoperative Intracranial Hypotension

Brain sag is a rare but serious postoperative complication after craniotomy. It is a clinical entity that refers to severe cerebrospinal fluid hypovolemia causing acute neurologic decompensation and obtundation. The established treatment is trendelenberg positioning. We present 3 cases of severe brain sag in which patients developed acute neurologic deterioration unresponsive to conventional treatment. An epidural blood patch was performed emergently to prevent further neurologic decline. The administration of epidural blood patch resulted in immediate and dramatic reversal of obtundation in each of these patients. Epidural blood patch may be a life-saving intervention in postcraniotomy patients presenting with refractory brain sag. It should be offered in patients who meet the criteria for brain sag and are unresponsive to conventional treatment modalities, despite the clinical presentation of herniation and coma.

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.

An atlas-based method to compensate for brain shift: Preliminary results

Compensating for intraoperative brain shift using computational models has shown promising results. Since computational time is an important factor during neurosurgery, a priori knowledge of the possible sources of deformation can increase the accuracy of model-updated image-guided systems. In this paper, a strategy to compensate for distributed loading conditions in the brain such as brain sag, volume changes due to drug reactions, and brain swelling due to edema is presented. An atlas of model deformations based on these complex loading conditions is computed preoperatively and used with a constrained linear inverse model to predict the intraoperative distributed brain shift. This relatively simple inverse finite-element approach is investigated within the context of a series of phantom experiments, two in vivo cases, and a simulation study. Preliminary results indicate that the approach recaptured on average 93% of surface shift for the simulation, phantom, and in vivo experiments. With respect to subsurface shift, comparisons were only made with simulation and phantom experiments and demonstrated an ability to recapture 85% of the shift. This translates to a remaining surface and subsurface shift error of 0.7+/-0.3 mm, and 1.0+/-0.4 mm, respectively, for deformations on the order of 1cm.

Herniation Secondary to Critical Postcraniotomy Cerebrospinal Fluid Hypovolemia

Cerebrospinal fluid hypovolemia resulting in postural headaches is a well-known clinical entity, but severe forms of cerebrospinal fluid hypovolemia with altered mental status and signs of transtentorial herniation ("brain sag") have rarely been reported. This article describes the clinical features of brain sag after craniotomy in an attempt to increase recognition of this syndrome. Between April 2001 and January 2003, 220 consecutive patients with subarachnoid hemorrhage were prospectively enrolled in the Columbia Subarachnoid Hemorrhage Outcomes Project; 137 underwent craniotomy for aneurysm clipping. Among these patients, the diagnosis of brain sag was made when all three of the following criteria were present: clinical signs of transtentorial herniation, head computed tomographic scans revealing effacement of the basal cisterns with an oblong brainstem, and improvement of symptoms after placement of the patient in the Trendelenburg position (-15 to -30 degrees). For each patient, the symptoms, clinical course, and subsequent response to treatment were characterized. In addition, brainstem dimensions were measured on computed tomographic scans taken before, during, and after resolution of brain sag. A "sag ratio" was generated for these time points by dividing the maximum anteroposterior distance by the maximum bipeduncular distance. Eleven (8.0%) of 137 aneurysmal subarachnoid hemorrhage patients treated by craniotomy and an intraoperative spinal drain met the criteria for brain sag. Signs of transtentorial herniation developed most commonly between 2 and 4 days postoperatively. Pupillary asymmetry was noted in 10 (91.0%) of 11 patients, whereas the other patient demonstrated extensor posturing. The Trendelenburg position reversed the symptoms in all patients. The mean sag ratios before, during, and after resolution of brain sag were 0.91 +/- 0.03 (mean +/- standard error), 1.18 +/- 0.03, and 0.91 +/- 0.03, respectively. This represented a 30.9% elongation of the brainstem during sag (P < 0.001) and a 23.6% change back to baseline after resolution of the syndrome (P < 0.002). There was no significant difference between the presag and postsag ratios. Severe cerebrospinal fluid hypovolemia after craniotomy may produce a dramatic herniation syndrome that is completely reversed by the Trendelenburg position. Brain sag should be included in the differential diagnosis for acute postoperative clinical deterioration in this patient population.

Methylergonovine maleate (methergine) relieves postdural puncture headache in obstetric patients

Sir, Postdural puncture headache (PDPH) is usually related to persistence of the dural hole, with leakage of cerebrospinal fluid into the surrounding soft tissue. This leads to lowering of cerebrospinal fluid pressure. This in turn produces intracranial venous dilatation resulting in an increase in brain volume (Monro–Kellie doctrine) (1). This increase in brain volume results in brain sag, which exerts traction on the surrounding nerves, vessels and meninges resulting in headache. Methylergonovine maleate (methergine) is a semisynthetic derivative of the ergot alkaloid. Stimulation of vascular smooth muscles by ergot alkaloid through their agonist action at α-adrenergic receptors is the basis for their usefulness in the treatment of migraine headaches 2-4). We planned a pilot study to evaluate the usefulness of methergine in relieving PDPH in obstetric patients based on this observation. The study was conducted on 25 obstetric patients (ASA I and II, aged 18–30 years), undergoing cesarean section under spinal anesthesia, who developed PDPH that was not relieved by bedrest, analgesics and fluids for 24 h. Following approval by the Board of Studies, these patients were administered oral tablets of methergine, 0.25 mg three times a day for 24 h. If the intensity of headache reduced or disappeared within 24 h, the treatment was carried on for a further 48 h. Tablet metoclopramide 10 mg twice a day was also advised as a prophylactic antiemetic. At 8-h intervals, patients were asked to rate their intensity of headache on a Visual Analog Scale (VAS; 1 = no headache, 10 = maximum headache). All of the patients except one (4%) showed improvement in the intensity of headache within 24 h. Of these 24 (96%) patients who responded, headache disappeared completely in four (16%) patients, and reduced to less than half in the remaining 20 (80%) (VAS < 5) in the first 24 h. By the third day all of these 24 patients were completely relieved of their headache. Only one (4%) patient who showed no improvement in her condition had to undergo the application of an epidural blood patch for relief of PDPH. The probable mechanism of action of methergine in PDPH is the vasoconstriction of cranial and extracranial vessels leading to decrease in brain volume and corresponding traction on vessels, nerves and meninges. In conclusion, this preliminary trial suggests that tablet methergine can be successfully used to relieve PDPH in postcesarean section patients.

Intracranial hypotension without meningeal enhancement on magnetic resonance imaging

Meningeal enhancement on magnetic resonance (MR) imaging is considered the hallmark radiological feature of intracranial hypotension. The authors report on a patient who exhibited progressively symptomatic intracranial hypotension due to a lumbar cerebrospinal fluid (CSF) leak, but in whom MR imaging demonstrated no pachymeningeal enhancement. This 24-year-old man presented with a 6-week history of progressive orthostatic headaches that were associated with photo- and phonophobia. Four weeks before the onset of the headaches, the patient had undergone a lumbar laminectomy. Brain MR images revealed subdural fluid collections and brain sagging; however, meningeal enhancement was not present. Myelography demonstrated a CSF leak at the site of the laminectomy. At surgery, a large dural tear was repaired. The patient recovered well from the surgery, with complete resolution of his headaches. The absence of meningeal enhancement on MR imaging does not exclude a diagnosis of symptomatic intracranial hypotension.

Acquired Chiari I malformation secondary to spontaneous spinal cerebrospinal fluid leakage and chronic intracranial hypotension syndrome in seven cases.

Spontaneous spinal cerebrospinal fluid (CSF) leakage with development of the intracranial hypotension syndrome and acquired Chiari I malformation due to lumbar spinal CSF diversion procedures have both been well described. However, concomitant presentation of both syndromes has rarely been reported. The object of this paper is to present data in seven cases in which both syndromes were present. Three illustrative cases are reported in detail. The authors describe seven symptomatic cases of spontaneous spinal CSF leakage with chronic intracranial hypotension syndrome in which magnetic resonance (MR) images depicted dural enhancement, brain sagging, loss of CSF cisterns, and acquired Chiari I malformation. This subtype of intracranial hypotension syndrome probably results from chronic spinal drainage of CSF or high-flow CSF shunting and subsequent loss of brain buoyancy that results in brain settling and herniation of hindbrain structures through the foramen magnum. Of 35 cases of spontaneous spinal CSF leakage identified in the authors' practice over the last decade, MR imaging evidence of acquired Chiari I malformation has been shown in seven. Not to be confused with idiopathic Chiari I malformation, ideal therapy requires recognition of the syndrome and treatment directed to the site of the spinal CSF leak.