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Benign intracranial hypertension
Classification and external resources
ICD-10G93.2
ICD-9348.2
OMIM243200
DiseasesDB1331
MedlinePlus000351
eMedicineneuro/329  oph/190 neuro/537
MeSHD011559

Idiopathic intracranial hypertension (IIH), sometimes called benign intracranial hypertension (BIH) or pseudotumor cerebri (PTC) is a neurological disorder that is characterized by increased intracranial pressure (ICP), in the absence of a tumor or other diseases affecting the brain or its lining. The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings G00-G99 - Diseases of the Nervous system (G00-G09 Inflammatory diseases of the Central nervous system ( Bacterial meningitis The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Mendelian Inheritance in Man project is a Database that catalogues all the known Diseases with a genetic component, and—when possible—links them The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Intracranial pressure, ( ICP) is the pressure exerted by the Cranium on the Brain tissue Cerebrospinal fluid (CSF and the brain's circulating The meninges (singular meninx) is the system of membranes which envelops the Central nervous system. The main symptoms are headache and visual problems. A headache ( cephalalgia in medical terminology is a condition of pain in the Head; sometimes Neck or upper back pain may also be interpreted Diagnosis requires brain scans and lumbar puncture. Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function/ Pharmacology of the Brain In Medicine, a lumbar puncture (colloquially known as a spinal tap) is a Diagnostic and at times therapeutic procedure that is performed in order There are various medical and surgical treatments.

Contents

Terminology

The terms "benign" and "pseudotumor" derive from the fact that increased intracranial pressure was, especially in the era before computed tomography (CT), associated with brain tumors. Computed tomography (CT is a Medical imaging method employing Tomography. A brain tumor is any intracranial Tumor created by abnormal and uncontrolled cell division, normally either in the Brain itself ( Neurons Those patients in whom no tumour was found were therefore diagnosed with "pseudotumor cerebri" (a disease mimicking a brain tumor). The disease was renamed "benign intracranial hypertension" to distinguish it from intracranial hypertension due to malignancy (i. e. cancer); this was also felt to be misleading, and the name was therefore revised to "idiopathic (of no identifiable cause) intracranial hypertension". [1]

Raised ICP due to another cause (e. g. meningitis, tumor) can be classified as "secondary intracranial hypertension". Meningitis is Inflammation of the protective membranes covering the Brain and Spinal cord, known collectively as the Meninges.

Signs and symptoms

Characteristic features of IIH are headache (worse in the morning, associated with nausea) and vision problems, such as double vision, transient visual obscurations, loss of peripheral sight or blurring of vision. Diplopia, commonly known as double vision, is the simultaneous Perception of two images of a single object If untreated, complete loss of vision is possible. While IIH may develop in any age group and in both males and females, it is more likely in females of fertile age (15-45) who are overweight or obese. Obesity is a condition in which excess Body fat has accumulated to such an extent that health may be negatively affected Certain medications (hormonal contraception, vitamin A,[2] tetracycline antibiotics) may increase risk of IIH. Hormonal contraception refers to Birth control methods that act on the hormonal system Vitamin A refers to a family of similarly shaped molecules the Retinoids. Tetracyclines are a group of Broad-spectrum antibiotics whose general usefulness has been reduced with the onset of bacterial resistance [3]

Physical findings in IIH are characterized by papilledema, loss of visual acuity and visual fields, and absence of focal neurological findings (e. Papilledema (or papilloedema) is Optic disc swelling that is caused by increased Intracranial pressure. The term visual field is sometimes used as a Synonym to Field of view, though they do not designate the same thing g. face, arm or leg weakness, sensory disturbance or coordination loss). Diplopia (double vision), if present, may be due to abducens nerve palsy (the sixth cranial nerve). The abducens nerve (the sixth cranial nerve, also called the sixth nerve or simply VI) is a “somatic efferent” nerve that controls the movement of a Cranial nerves are Nerves that emerge directly from the Brain stem in contrast to Spinal nerves which emerge from segments of the Spinal cord. [3] Absence of papilledema, while making IIH less likely, is possible. [4]

Diagnosis

The diagnosis may be suspected on the basis of the history and examination. To confirm the diagnosis, as well as excluding alternative causes (such as a brain tumor), several investigations are required; more investigations may be performed if the history is not typical or the patient is more likely to have an alternative problem (e. A brain tumor is any intracranial Tumor created by abnormal and uncontrolled cell division, normally either in the Brain itself ( Neurons g. children, the elderly). [3]

Neuroimaging, usually with computed tomography (CT/CAT) or magnetic resonance imaging (MRI), rules out mass lesions. Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function/ Pharmacology of the Brain Computed tomography (CT is a Medical imaging method employing Tomography. In IIH these scans may be normal, although small or slit-like ventricles and "empty sella sign" (flattening of the pituitary gland due to increased pressure) may be seen. The ventricular system is a set of structures in the Brain continuous with the Central canal of the Spinal cord. Empty sella syndrome (abbreviated ESS) is a disorder that involves the Sella turcica, a bony structure at the base of the brain that surrounds and protects the The pituitary gland, or hypophysis, is an Endocrine gland about the size of a Pea. Some propose MRI as preferred mode of imaging in atypical cases, and suggest performance of MR venography to exclude venous obstruction or cerebral venous sinus thrombosis. Cerebral venous sinus thrombosis ( CVST) is a rare form of Stroke that results from Thrombosis (a blood clot of the Dural venous sinuses, which [3]

Once a mass lesion has been ruled out, lumbar puncture is generally performed to measure the opening pressure, as well as to obtain cerebrospinal fluid to exclude alternative diagnoses such as low-grade viral meningitis. In Medicine, a lumbar puncture (colloquially known as a spinal tap) is a Diagnostic and at times therapeutic procedure that is performed in order Cerebrospinal fluid ( CSF) Liquor cerebrospinalis, is a clear Bodily fluid that occupies the Subarachnoid space and the Ventricular system Meningitis is Inflammation of the protective membranes covering the Brain and Spinal cord, known collectively as the Meninges. If the opening pressure is increased, CSF may be removed for relief (see below). [3]

Criteria

The original criteria for IIH were described by Dandy in 1937. Walter Edward Dandy ( April 6, 1886 -- April 19, 1946) was an American Neurosurgeon and scientist [5] They were modified by Smith in 1985 to become the "modified Dandy criteria". [6]

Modified Dandy criteria[6]
1 Signs & symptoms of increased ICP – CSF pressure >25 cmH2O
2 No localizing signs with the exception of abducens nerve palsy
3 Normal CSF composition
4 Normal to small (slit) ventricles on imaging with no intracranial mass

A 2002 review proposed a 6-point set of criteria that required no unexplained symptoms or signs, measurement of the CSF opening pressure in the lateral decubitus (i. e. lying on the side), exclusion of any other causes on specific forms of imaging. [3]

Pathogenesis

At least two primary mechanisms for the development of increased CSF pressure in primary IIH have been postulated: increased production of CSF and reduced resorption. Increased production may be the result of vasogenic extracellular brain edema, while decreased rebsorption may be due to low conductance of CSF outflow at the arachnoid villi. Arachnoid granulations (or arachnoid villi) are small protrusions of the arachnoid (the thin second layer covering the brain through the Dura (the thick [7][8] Sørensen et al found evidence for increased water diffusion in the brain of IIH patients when compared to normal subjects. [8] It was argued that this evidence indicates abnormal convective transependymal water flow leading to brain edema. However, this theory remains controversial, as a similar study conducted by Bastin et al that used significantly disparate MR imaging protocols was unable to reproduce these findings. [9] Normal CSF flow involves production at the choroid plexuses and absorption at the cranial and spinal nerve root arachnoid villi and granulations. The choroid plexus is the area on the ventricles of the brain where Cerebrospinal fluid (CSF is produced by modified Ependymal cells. The term spinal nerve generally refers to the mixed spinal Nerve, which is formed from the dorsal and ventral roots that come out of the Spinal cord. Impaired CSF absorption at the superior sagittal sinus or along the spinal nerve roots could therefore explain IIH and has been documented in 75-100% of IIH patients. The superior sagittal sinus (also known as the superior longitudinal sinus) within a human Cranium, is an area above/behind the brain which allows Blood veins [7] Permeability along the blood-CSF barrier varies, producing an increasing oncotic pressure gradient between the CSF and venous system in a rostral to caudal progression. Oncotic pressure in the Circulatory system is a form of Osmotic pressure exerted by Proteins in Blood plasma that normally tends to pull In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species [10] It is speculated that variations in this oncotic pressure contribute to or impede CSF absorption. The mechanism remains unclear however, since high CSF protein concentrations, as commonly found in Guillain-Barré syndrome or spinal tumors, can manifest as intracranial hypertension, whereas individuals with IIH frequently present with normal-to-low CSF protein findings. [7]

Treatment

The primary goal in treatment of IIH is the prevention of visual loss and blindness. IIH is treated mainly through the attempted reduction of CSF pressure and, where applicable, weight loss. IIH may resolve after initial treatment, may go into remission and relapse at a later stage, or may continue chronically. [3] If the intracranial hypertension is secondary to medication, these need to be discontinued.

Lumbar puncture

CSF pressure may be temporarily decreased by repeated "therapeutic" (as opposed to diagnostic) lumbar punctures (to remove excessive cerebrospinal fluid). In Medicine, a lumbar puncture (colloquially known as a spinal tap) is a Diagnostic and at times therapeutic procedure that is performed in order Cerebrospinal fluid ( CSF) Liquor cerebrospinalis, is a clear Bodily fluid that occupies the Subarachnoid space and the Ventricular system However, this is generally regarded as a "holding measure" until medical or surgical treatment has been instituted. [3][11]

Medication

The best studied medical treatment is the carbonic anhydrase inhibitor acetazolamide, which reduces CSF production. The carbonic anhydrases (or carbonate dehydratases) form a family of Enzymes that catalyze the rapid conversion of Carbon dioxide to Bicarbonate Acetazolamide, sold under the trade name Diamox, is a Carbonic anhydrase inhibitor that is used to treat Glaucoma, Epileptic seizures Benign [3] Other drugs such as furosemide and various diuretics, and topiramate may be used in an attempt to reduce ICP. Furosemide ( INN) or frusemide (former BAN) is a Loop diuretic used in the treatment of congestive Heart failure and Edema Topiramate (brand name Topamax) is an Anticonvulsant drug produced by Ortho-McNeil Neurologics and Noramco Inc The long-term use of corticosteroids to treat chronic IH has fallen out of favor, unless there is a secondary inflammatory process caused by an underlying disease like lupus or Behcet disease. While corticosteroids may lower intracranial pressure in the short-term, the drawbacks to steroids include weight gain, fluid retention and a rebound in intracranial pressure during the drug’s withdrawal. [12]

Surgery

Surgical treatments include optic nerve sheath decompression and fenestration. In this procedure, a slit is made in the sheath of the optic nerve, which can alleviate swelling and slow or halt loss of vision. The optic nerve, also called cranial nerve II, is the Nerve that transmits visual information from the Retina to the Brain. [13] Optic nerve sheath fenestration is less effective in controlling the CSF pressure (and in controlling most symptoms, such as headache), but is more effective in protecting the optic nerve from the effects of pressure.

Shunting is a neurosurgical procedure to facilitate the drainage of excess CSF (thereby reducing ICP). Neurosurgery is the surgical discipline focused on treating those central, Peripheral nervous system and spinal column diseases amenable to surgical A shunt is essentially a silicone tube inserted somewhere in the fluid spaces of the central nervous system, which then drains CSF to the circulatory system or one of the body cavities. In Medicine, a shunt is a hole or passage which moves or allows movement of fluid from one part of the body to another In Vertebrates the central nervous system ( CNS) is the part of the Nervous system which is enclosed in the Meninges. There are various types and configurations of shunts; lumboperitoneal (LP) shunts drain from the lumbar spine to the peritoneal cavity, while ventriculoatrial (VA) shunts run from the cerebral ventricles to the heart. The peritoneal cavity is a potential space between the parietal Peritoneum and visceral peritoneum The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic Although shunts can dysfunction due to occlusion, infection, malfunction, etc. , they are very effective in normalizing CSF pressures. The absence of papilledema or longstanding symptoms make successful shunting less likely. [14] Studies have shown that shunting procedures are becoming more common as the rate of severe obesity rises. [11]

In cases of severe obesity, gastric bypass surgery has been shown to lead to a marked improvement in symptoms. Gastric bypass procedures (GBP are any of a group of similar operations used to treat Morbid obesity —the severe accumulation of excess weight as fatty tissue—and the health [15]

Epidemiology

The reported annual incidence of IIH is <20 per 100,000 persons. [3]

History

The first report of IIH is usually ascribed to the German physician Heinrich Quincke, who described it in 1893 under the name "serous meningitis". Heinrich Irenaeus Quincke ( 26 August 1842 - 19 May 1922) was a German internist and Surgeon. [16] The term "pseudotumor cerebri" was introduced in 1904 by Max Nonne. Max Nonne (born January 13 1861, Hamburg - died 1959 was a German Neurologist. [17] Diagnostic criteria were developed in 1937 by the Baltimore neurosurgeon Walter Dandy. Walter Edward Dandy ( April 6, 1886 -- April 19, 1946) was an American Neurosurgeon and scientist [5][18]

References

  1. ^ Bandyopadhyay S (2001). "Pseudotumor cerebri". Arch. Neurol. 58 (10): 1699–701. doi:10.1001/archneur.58.10.1699. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 11594936.  
  2. ^ Jacobson DM, Berg R, Wall M, Digre KB, Corbett JJ, Ellefson RD (1999). "Serum vitamin A concentration is elevated in idiopathic intracranial hypertension". Neurology 53 (5): 1114–8. PMID 10496276.  
  3. ^ a b c d e f g h i j Friedman, DI; Jacobson DM (2002). "Diagnostic criteria for idiopathic intracranial hypertension". Neurology 59 (10): 1492-1495. PMID 12455560.  
  4. ^ Marcelis J, Silberstein SD (1991). "Idiopathic intracranial hypertension without papilledema". Arch. Neurol. 48 (4): 392–9. PMID 2012512.  
  5. ^ a b Dandy WE (Oct 1937). "Intracranial pressure without brain tumor - diagnosis and treatment". Ann Surg 106 (4): 492-513. doi:10.1097/00000658-193710000-00002. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  6. ^ a b Smith JL (1985). "Whence pseudotumor cerebri?". Journal of clinical neuro-ophthalmology 5 (1): 55–6. PMID 3156890.  
  7. ^ a b c Skau M, Brennum J, Gjerris F, Jensen R (2006). "What is new about idiopathic intracranial hypertension? An updated review of mechanism and treatment". Cephalalgia 26 (4): 384–99. doi:10.1111/j.1468-2982.2005.01055.x. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 16556239.  
  8. ^ a b Sørensen PS, Thomsen C, Gjerris F, Schmidt J, Kjaer L, Henriksen O (1989). "Increased brain water content in pseudotumour cerebri measured by magnetic resonance imaging of brain water self diffusion". Neurol. Res. 11 (3): 160–4. PMID 2573851.  
  9. ^ Bastin ME, Sinha S, Farrall AJ, Wardlaw JM, Whittle IR (2003). "Diffuse brain oedema in idiopathic intracranial hypertension: a quantitative magnetic resonance imaging study". J. Neurol. Neurosurg. Psychiatr. 74 (12): 1693–6. PMID 14638893.  
  10. ^ Walker RW (2001). "Idiopathic intracranial hypertension: any light on the mechanism of the raised pressure?". J. Neurol. Neurosurg. Psychiatr. 71 (1): 1–5. PMID 11413251.  
  11. ^ a b Curry WT, Butler WE, Barker FG (2005). "Rapidly rising incidence of cerebrospinal fluid shunting procedures for idiopathic intracranial hypertension in the United States, 1988-2002". Neurosurgery 57 (1): 97–108; discussion 97–108. doi:10.1227/01.NEU.0000163094.23923.E5. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 15987545.  
  12. ^ IHRF Medication and Surgery.
  13. ^ Banta JT, Farris BK (2000). "Pseudotumor cerebri and optic nerve sheath decompression". Ophthalmology 107 (10): 1907–12. doi:10.1016/S0161-6420(00)00340-7. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 11013197.  
  14. ^ McGirt MJ, Woodworth G, Thomas G, Miller N, Williams M, Rigamonti D (2004). "Cerebrospinal fluid shunt placement for pseudotumor cerebri-associated intractable headache: predictors of treatment response and an analysis of long-term outcomes". J. Neurosurg. 101 (4): 627–32. PMID 15481717.  
  15. ^ Sugerman HJ, Felton WL, Sismanis A, Kellum JM, DeMaria EJ, Sugerman EL (1999). "Gastric surgery for pseudotumor cerebri associated with severe obesity". Ann. Surg. 229 (5): 634–40; discussion 640–2. doi:10.1097/00000658-199905000-00005. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 10235521.  
  16. ^ Quincke HI (1893). "Meningitis serosa". Samml Klin Vortr 67: 655.  
  17. ^ Nonne M (1904). "Ueber Falle vom Symptomkomplex "Tumor Cerebri" mit Ausgang in Heilung (Pseudotumor Cerebri)" (in German). Dtsch Z Nervenheil 27: 169-216.  
  18. ^ Johnston I (2001). "The historical development of the pseudotumor concept". Neurosurg Focus 11 (2): 1. doi:10.3171/foc.2001.11.2.3. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 16602675.  

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