Serum glial fibrillary acidic protein (GFAP)-antibody in idiopathic intracranial hypertension

Neurofilament light chain is elevated in patients with newly diagnosed idiopathic intracranial hypertension: A prospective study

BACKGROUND

Idiopathic intracranial hypertension is a secondary headache disorder potentially causing visual loss. Neurofilament light chain is a candidate, prognostic biomarker, but further studies of neuronal biomarkers are needed. Our objective was to investigate neurofilament light chain in cerebrospinal fluid (cNfL) and plasma (pNfL), amyloid-beta 42 (Aβ-42), total-tau and phosphorylated-tau in cerebrospinal fluid in new-onset idiopathic intracranial hypertension.

METHODS

Prospective case-control study including new-onset idiopathic intracranial hypertension and age, sex and BMI matched controls. Biomarkers were compared between patients and controls and related to papilledema, visual fields and opening pressure.

RESULTS

We included 37 patients and 35 controls. Patients had higher age-adjusted cNfL (1.4 vs. 0.6 pg/mL, p-adjusted < 0.001), pNfL (0.5 vs. 0.3 pg/mL, p-adjusted < 0.001) and total-tau/Aβ-42 (0.12 vs. 0.11, p-adjusted = 0.039). Significant, positive linear correlations were found between cNfL, pNfL, total-tau/Aβ-42 and opening pressure. Patients with severe papilledema had elevated cNfL compared to mild-moderate papilledema (median cNfL: 4.3 pg/mL (3.7) versus 1.0 pg/mL (1.4), p-adjusted = 0.009). cNFL was inversely associated with perimetric mean deviation (r = -0.47, p-adjusted < 0.001).

CONCLUSIONS

cNfL, pNfL and total-tau/Aβ-42 were elevated in new-onset idiopathic intracranial hypertension. cNfL was associated with severity of papilledema and visual field defects at diagnosis. This indicates early axonal damage. Neurofilament light chain is a candidate biomarker for disease severity.

Beyond Myelin Oligodendrocyte Glycoprotein and Aquaporin-4 Antibodies: Alternative Causes of Optic Neuritis

Optic neuritis (ON) is the most common cause of vision loss in young adults. It manifests as acute or subacute vision loss, often accompanied by retrobulbar discomfort or pain during eye movements. Typical ON is associated with Multiple Sclerosis (MS) and is generally mild and steroid-responsive. Atypical forms are characterized by unusual features, such as prominent optic disc edema, poor treatment response, and bilateral involvement, and they are often associated with autoantibodies against aquaporin-4 (AQP4) or Myelin Oligodendrocyte Glycoprotein (MOG). However, in some cases, AQP4 and MOG antibodies will return as negative, plunging the clinician into a diagnostic conundrum. AQP4- and MOG-seronegative ON warrants a broad differential diagnosis, including autoantibody-associated, granulomatous, and systemic disorders. These rare forms need to be identified promptly, as their management and prognosis are greatly different. The aim of this review is to describe the possible rarer etiologies of non-MS-related and AQP4- and MOG-IgG-seronegative inflammatory ON and discuss their diagnoses and treatments.

Visual System Involvement in Glial Fibrillary Acidic Protein Astrocytopathy: Two Case Reports and a Systematic Literature Review

BACKGROUND AND OBJECTIVES

Glial fibrillary acidic protein (GFAP) antibodies can associate with an astrocytopathy often presenting as a meningoencephalitis. Visual involvement has been reported but scarcely defined. We describe 2 cases of GFAP astrocytopathy with predominant visual symptoms and present a systematic review of the literature.

METHODS

We describe 2 patients with GFAP astrocytopathy from our neurology department. We performed a systematic review of the literature according to PRISMA guidelines, including all patients with this disease and available clinical data, focusing on visual involvement.

RESULTS

Patient 1 presented with bilateral optic disc edema and severe sudden bilateral loss of vision poorly responsive to therapy. Patient 2 showed bilateral optic disc edema, headache, and mild visual loss with complete recovery after steroids. We screened 275 records and included 84 articles (62 case reports and 22 case series) for a total of 592 patients. Visual involvement was reported in 149/592 (25%), with either clinical symptoms or paraclinical test-restricted abnormalities. Bilateral optic disc edema was found in 80/159 (50%) of patients investigated with fundoscopy, among which 49/80 (61%) were asymptomatic. One hundred (100/592, 17%) reported visual symptoms, often described as blurred vision or transient visual obscurations. Optic neuritis was rare and diagnosed in only 6% of all patients with GFAP astrocytopathy, often without consistent clinical and paraclinical evidence to support the diagnosis. Four patients (including patient 1) manifested a severe, bilateral optic neuritis with poor treatment response. In patients with follow-up information, a relapsing disease course was more frequently observed in those with vs without visual involvement (35% vs 11%, p = 0.0035, OR 3.6 [CI 1.44-8.88]).

DISCUSSION

Visual system involvement in GFAP astrocytopathy is common and heterogeneous, ranging from asymptomatic bilateral optic disc edema to severe bilateral loss of vision, but optic neuritis is rare. GFAP CSF antibody testing should be considered in patients with encephalitis/meningoencephalitis or myelitis and bilateral optic disc edema, even without visual symptoms, and in patients with severe bilateral optic neuritis, especially when AQP4 antibodies are negative. Visual symptoms might associate with a higher relapse risk and help to identify patients who may require chronic immunosuppression.

Case report: Revealing a special and rare autoimmune GFAP astrocytopathy in the spinal cord succeeding Neurobrucellosis infection

Brucellosis, a zoonosis, can cause an inflammatory response in most organs and continues to be a public health problem in some endemic areas, whereas neurobrucellosis is a morbid form of brucellosis that affects the central nervous system (CNS) with poor prognosis. Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is an autoimmune disease, and there have been no reports of a Brucella infection, leading to GFAP astrocytopathy. We report the case of a patient with a positive and high level of GFAP antibodies in the cerebrospinal fluid (CSF), following a Brucella infection. Although this patient did not show any responsible lesions in the diffusion sequence of the magnetic resonant imaging (MRI) scan, we found an evidence of thoracolumbar (T12) involvement on fluorodeoxyglucose (FDG) positron emission tomography (PET). The symptoms of spinal cord involvement were only partly relieved after initial treatment [doxycycline (0.1 g Bid) and rifampicin (0.6 g Qd) for 6 weeks]; however, they markedly improved after the subsequent immunosuppressive therapy [intravenous methylprednisolone (1,000 mg for 3 days)], followed by a 50% reduction from the preceding dose after 3 days, and subsequently, oral prednisone tablets (60 mg/day) was started, which was then gradually tapered [reduced to 10 mg/day every 1–2 weeks)]. The positive response to immunosuppressive therapy and treatment outcome strongly indicated the presence of an autoimmune neurological disease probably triggered by some infectious factors. Therefore, our findings reveal that a Brucella infection is one of the causes of autoimmune GFAP astrocytopathy, and when this infection is difficult to be identified by regular MRI, FDG PET can be used as a supplementary method for diagnosis and treatment.

A New Perspective on the Pathophysiology of Idiopathic Intracranial Hypertension: Role of the Glia-Neuro-Vascular Interface

Idiopathic intracranial hypertension (IIH) is a neurological disease characterized by symptoms and signs of increased intracranial pressure (ICP) of unknown cause. Most attention has been given to the role of cerebrospinal fluid (CSF) disturbance and intracranial venous hypertension caused by sinus vein stenosis. We previously proposed that key pathophysiological processes take place within the brain at the glia-neuro-vascular interface. However, the relative importance of the proposed mechanisms in IIH disease remains unknown. Modern treatment regimens aim to reduce intracranial CSF and venous pressures, but a substantial proportion of patients experience lasting complaints. In 2010, the first author established a database for the prospective collection of information from individuals being assessed for IIH. The database incorporates clinical, imaging, physiological, and biological data, and information about treatment/outcome. This study retrieved information from the database, asking the following research questions: In IIH subjects responding to shunt surgery, what is the occurrence of signs of CSF disturbance, sinus vein stenosis, intracranial hypertension, and microscopic evidence of structural abnormalities at the glia-neuro-vascular interface? Secondarily, do semi-quantitative measures of abnormal ultrastructure at the glia-neurovascular differ between subjects with definite IIH and non-IIH (reference) subjects? The study included 13 patients with IIH who fulfilled the diagnostic criteria and who improved following shunt surgery, i.e., patients with definite IIH. Comparisons were done regarding magnetic resonance imaging (MRI) findings, pulsatile and static ICP scores, and immune-histochemistry microscopy. Among these 13 IIH subjects, 6/13 (46%) of patients presented with magnetic resonance imaging (MRI) signs of CSF disturbance (empty sella and/or distended perioptic subarachnoid spaces), 0/13 (0%) of patients with IIH had MRI signs of sinus vein stenosis, 13/13 (100%) of patients with IIH presented with abnormal preoperative pulsatile ICP [overnight mean ICP wave amplitude (MWA) above thresholds], 3/13 (23%) patients showed abnormal static ICP (overnight mean ICP above threshold), and 12/13 (92%) of patients with IIH showed abnormal structural changes at the glia-neuro-vascular interface. Comparisons of semi-quantitative structural variables between IIH and aged- and gender-matched reference (REF) subjects showed IIH abnormalities in glial cells, neurons, and capillaries. The present data suggest a key role of disease processes affecting the glia-neuro-vascular interface.

Modulation of astrocyte activity and improvement of oxidative stress through blockage of NO/NMDAR pathway improve posttraumatic stress disorder (PTSD)-like behavior induced by social isolation stress

BACKGROUND

It has been well documented that social isolation stress (SIS) can induce posttraumatic stress disorder (PTSD)-like behavior in rodents, however, the underlying mechanism is remained misunderstood. In the current study, we aimed to elucidate the role of NO/NMDAR pathway in PTSD-like behavior through modulating of astrocyte activity and improvement of oxidative stress.

METHODS

Male NMRI mice were used to evaluate the memory function by using Morris water maze (MWM) and fear memory extinction by using freezing response. We used MK-801 (NMDAR-antagonist), L-NNA (NOS-inhibitor), NMDA (NMDAR-agonist), and L-arginine (NO-agent) to find a proper treatment. Also, immunohistochemistry, RT-PCR, and oxidative stress assays were used to evaluate the levels of astrocytes and oxidative stress. We used five mice in each experimental task.

RESULTS

Our results revealed that SIS could induce learning and memory dysfunction as well as impairment of fear memory extinction in MWM and freezing response tests, respectively. Also, we observed that combined treatment including blockage of NOS (by L-NNA, 0.5 mg/kg) and NMDAR (by MK-801, 0.001 mg/kg) at subeffective doses could result in improvement of both memory and fear memory. In addition, we observed that SIS significantly increases the GFAP expression and astrocyte activity, which results in significant imbalance in oxidative stress. Coadministration of MK-801 and L-NNA at subeffective doses not only decreases the expression of GFAP, but also regulates the oxidative stress imbalance CONCLUSION: Based on these results, it could be hypothesized that blockage of NO/NMDAR pathway might be a novel treatment for PTSD-like behavior in animals by inhibiting the astrocyte and regulating oxidative stress level.

Case Report: Need for Caution in the Diagnosis of GFAP Astrocytopathy—A Case of GFAP Astrocytopathy Coexistent With Primary Central Nervous System Lymphoma

We reported a case of primary central nervous system lymphoma (PCNSL) coexistent with glial fibrillary acidic protein (GFAP) astrocytopathy, and discussed the problems needing attention in the diagnosis and differential diagnosis of GFAP astrocytopathy. Our patient was a 51-year-old female who presented with somnolence for a month, and memory declination for 10 days. Brain magnetic resonance imaging (MRI) demonstrated multiple abnormal enhancement lesions in bilateral basal ganglia and around the third ventricle, as well as transient T2-weighted hyper-intensity lesions at the splenium of the corpus callosum during the course of the disease. The cerebrospinal fluid (CSF) was positive for anti-GFAP antibodies by antigen-transfected HEK293 cell-based assay (indirect immunofluorescence assay). She was initially diagnosed with autoimmune GFAP astrocytopathy. After treatment with corticosteroids for about 2 months, she displayed poor response and even worsened clinical manifestations when the dose of prednisone reduced to 45 mg. Stereotactic brain biopsy was adopted and the diagnosis of large B-cell lymphoma, non-germinal center type was established on pathological examination. The results of brain biopsy also showed perivascular inflammation and CD8+ T cell infiltration, which also accorded with GFAP astrocytopathy. After chemotherapy with rituximab and methotrexate, the patient showed clinical and radiological improvement significantly. Our findings suggest that positivity of GFAP antibody calls for cautious interpretation. Cancer screening appropriate for age, sex, and risk factors is recommended for GFAP antibody-positive patients, especially for patients with atypical clinical and radiologic manifestations.

Idiopathic intracranial hypertension: an illustrated guide for the trainee radiologist

Idiopathic intracranial hypertension is characterized by increased intracranial pressure, headache, and visual perturbations. Although the pathophysiology of idiopathic intracranial hypertension is obscure, several mechanisms have been proposed, such as increased cerebral blood volume, excessive cerebrospinal fluid volume (due to high production or impaired resorption), and inflammatory mechanisms as a likely cause of or contributor to impaired cerebrospinal fluid circulation. It predominantly affects women of reproductive age who are overweight or obese. The most common symptoms are daily headache, synchronous pulsatile tinnitus, transient visual perturbations, and papilledema with visual loss. The main neuroimaging findings are a partially empty sella turcica; flattening of the posterior sclera; transverse sinus stenosis (bilateral or in the dominant sinus); a prominent perioptic subarachnoid space, with or without optic nerve tortuosity; and intraocular protrusion of the optic nerve head. The main complication of idiopathic intracranial hypertension is visual loss. Within this context, neuroimaging is a crucial diagnostic tool, because the pathology can be reversed if properly recognized and treated early.

Papilledema: A review of etiology, pathophysiology, diagnosis, and management

Papilledema is optic nerve head edema secondary to raised intracranial pressure (ICP). It is distinct from other causes of optic disk edema in that visual function is usually normal in the acute phase. Papilledema is caused by transmission of elevated ICP to the subarachnoid space surrounding the optic nerve that hinders axoplasmic transport within ganglion cell axons. There is ongoing controversy as to whether axoplasmic flow stasis is produced by physical compression of axons or microvascular ischemia. The most common cause of papilledema, especially in patients under the age of 50, is idiopathic intracranial hypertension (IIH); however, conditions that decrease cerebrospinal fluid (CSF) outflow by either causing CSF derangements or mechanically blocking CSF outflow channels, and rarely conditions that increase CSF production, can be the culprit. When papilledema is suspected clinically, blood pressure should be measured, and pseudopapilledema should be ruled out. Magnetic resonance imaging of the brain and orbits with venography sequences is the preferred neuroimaging modality that should be performed next to look for indirect imaging signs of increased ICP and to rule out nonidiopathic causes. Lumbar puncture with measurement of opening pressure and evaluation of CSF composition should then be performed. In patients not in a typical demographic group for IIH, further investigations should be conducted to assess for underlying causes of increased ICP. Magnetic resonance imaging of the neck and spine, magnetic resonance angiography of the brain, computed tomography of the chest, complete blood count, and creatinine testing should be able to identify most secondary causes of intracranial hypertension. Treatment for patients with papilledema should be targeted toward the underlying etiology. Most patients with IIH respond to weight loss and oral acetazolamide. For patients with decreased central acuity and constricted visual fields at presentation, as well as patients who do not respond to treatment with acetazolamide, surgical treatments should be considered, with ventriculoperitoneal shunting being the typical procedure of choice.