ANMC Chiare Malformation-peds
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ANMC Chiare Malformation-peds
- 1. Chiari Malformations ANMC Department of Neurosurgery Jeff Stubblefield, PA-C Rob Lieberson, MD Rev. 11/8/2012
- 2. The Arnold-Chiari Eponym Hans Chiari (September 4, 1851 − May 6, 1916), an Austrian pathologist , described three seemingly related abnormalities at the base of the brain in 1891. Three years later, Julius Arnold (August 19, 1835 – February 3, 1915), a German pathologist, described one of the same abnormalities. The term "Arnold-Chiari malformation,” which placed Arnold’s name first, was coined by two of Arnold’s students in 1907.
- 3. Types of Chiari Malformation Type I Herniation of cerebellar tonsils Sometimes with syringomyelia Type II (Arnold- Chiari) Herniation of cerebellar vermis Usually accompanied by a lumbar myelomeningocele Type III Occipital encephalocele Usually with syringomyelia, a tethered cord and hydrocephalus Type IV Lack of cerebellar development Not compatible with life
- 4. Type I Herniation of cerebellar tonsils Sometimes with syringomyelia
- 5. Important Features 1. Small posterior fossa 2. Normally positioned fourth ventricle 3. Obliterated cisterna magna and, 4. Syringomyelia in 25%
- 6. 1. Syringomyelia ( /sɪˌrɪŋɡɵmaɪˈiːliə/) , or a syrinx, is a cyst or cavity within the spinal cord. 2. It may cause pain or weakness. a. Sensory complaints are usually in a “cape” distribution and most often affect pain and temperature sensation out of proportion to light touch. b. Weakness most often involves the hands but may spread. 3. Signs may develop slowly or come on suddenly with coughing, or straining. Syringomyelia
- 7. Surgery for Chiari I Malfor’n Tonsil Tonsil Spinal Cord IV Ventricle 1. Craniectomy 2. Dural Opening 3. Separation of Tonsils 4. Opening of IV Ventricle 5. Duroplasty
- 8. Type II (Arnold- Chiari) Herniation of cerebellar vermis Usually accompanied by a lumbar myelomeningocele 1. Small posterior fossa 2. Cerebellar vermian herniation 3. Extension of medulla below foramen magnum 4. Kinking of medulla (Z- formation) 5. Beaking of the quadrigeminal plate 6. Hydrocephalus 7. Myelomeningocele
- 9. Type III Occipital encephalocele Usually with syringomyelia, a tethered cord and hydrocephalus 1. Very small posterior fossa 2. High cervical or low occipital encephalocele 3. Varying amounts of brain herniate (cerebellum, occipital lobes, brainstem, etc.) 4. Herniated brain usually non- functional (necrosis, gliosis, heterotropias) 5. Usually, incompatible with life
- 10. Type IV Lack of cerebellar development Not compatible with life Archaic term 1. Very rare 2. Posterior fossa tiny and funnel shaped 3. Almost complete lack of cerebellum 4. Portions of brainstem may be absent 5. Spinal cord may be absent
- 11. 1. Enlargement of posterior fossa 2. Agenesis of cerebellar vermis 3. Cystic dilatation of 4th ventricle (ex vacuo) 4. Variable clinical manifestations 5. Hypothesized to result from arrest of cerebellar development prior to the 3rd month of gestation Dandy-Walker Malformation
- 12. Thank You
Notas del editor
- The Austrian pathologist Hans Chiari in the late 19th century described seemingly related anomalies of the hindbrain, the so called Chiari malformations I, II and III. Later, other investigators added a fourth (Chiari IV) malformation. The scale of severity is rated I - IV, with IV being the most severe. Types III and IV are very rare.[4] Hans Chiari (September 4, 1851 − May 6, 1916) was an Austrian pathologist who was a native of Vienna. He was the son of gynecologist Johann Baptist Chiari (1817–1854), and brother to rhinolaryngologist Ottokar Chiari (1853–1918). Chiari studied medicine in Vienna, where he was an assistant to Karl Freiherr von Rokitansky (1804–1878) and Richard Ladislaus Heschl (1824–1881). In 1878 he received his habilitation in pathological anatomy, and within a few years became an associate professor at the University of Prague. At Prague he was also superintendent of the pathological-anatomical museum. In 1906 he relocated to the University of Strasbourg as a professor of pathological anatomy. Chiari's research dealt largely with postmortem examinations, and most of his numerous writings are the result of autopsies. In 1891 he described a brain malformation that is characterized by abnormalities in the region where the brain and spinal cord meet, and it causes part of the cerebellum to protrude through the foramen magnum (bottom of the skull) into the spinal canal. This was to be called the Arnold-Chiari malformation, named after Chiari and German pathologist, Julius Arnold (1835–1915). The malformation was given its name in 1907 by two of Dr. Arnold's students. Another medical term named after Chiari is the Budd-Chiari syndrome, which is ascites and cirrhosis of the liver caused by an obstruction of the hepatic veins due to a blood clot. It is named in conjunction with British internist George Budd (1808–1882). Lastly, Chiari is also famous for describing the "Chiari network", an embryonic remnant found in the right atrium, first published in 1897. Julius Arnold (August 19, 1835 – February 3, 1915) was a German pathologist born in Zurich. He was the son of anatomist Friedrich Arnold (1803–1890). He studied medicine at the Universities of Heidelberg, Prague, Vienna and Berlin, where he was a student of Rudolf Virchow (1821–1902). In 1859 he became a doctor of medicine, and in 1866 he became a professor of pathological anatomy and director of the institute of pathology at Heidelberg. Arnold was the author of 120 articles in the fields of histology and pathological anatomy. His name is lent to a disorder known as Arnold–Chiari malformation, which occurs when the cerebellar tonsils and the medulla oblongata protrude through the foramen magnum into the spinal canal. Arnold described this malformation in an infant who died shortly after delivery, and published his account in an 1894 paper titled Myelocyste, Transposition von Gewebskeimen und Sympodie. In 1891, Austrian pathologist Hans Chiari (1851–1916) also described this disorder, three years prior to Arnold's findings. In 1907, two of Dr. Arnold's students coined the eponym of "Arnold-Chiari malformation" in honor of both men. Arnold died in 1915 in Heidelberg.
- Arnold–Chiari malformation, or often simply Chiari malformation, is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils through the foramen magnum (the opening at the base of the skull), sometimes causing non-communicating [1] hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow.[2] The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain. It can cause headaches, fatigue, muscle weakness in the head and face, difficulty swallowing, dizziness, nausea, impaired coordination, and, in severe cases, paralysis.[3] Type I. A congenital malformation. Is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils.[5][6][7] Tonsillar ectopia of more than 3 mm below foramen magnum. Syringomyelia of cervical or cervicothoracic spinal cord can be seen. Sometimes the medullary kink and brainstem elongation can be seen. Syndrome of occipitoatlantoaxial hypermobility is an acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.[8] Patients who exhibit extreme joint hypermobility and connective tissue weakness as a result of Ehlers-Danlos syndrome or Marfan Syndrome are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation. This type is difficult to diagnose and treat.[9] Headache, Neck Pain, Unsteady gait usually during childhood [5] Type II. Usually accompanied by a lumbar myelomeningocele or lumbosacral spine with herniation of the vermis below the foramen magnum.[5][10] As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement. Low lying torcular herophili, tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.[11] The position of the torcular herophili is important for distinction from Dandy-Walker syndrome in which it is classically upturned. This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging. Colpocephaly may be seen due to the associated neural tube defect. Paralysis below the spinal defect [5] Type III. It is associated with an occipital encephalocele containing a variety of abnormal neuroectodermal tissues. Syringomyelia and tethered cord as well as hydrocephalus is also seen.[5][12] Causes abundant neurological deficits [5] Type IV. Characterized by a lack of cerebellar development in which the cerebellum and brain stem lie within the posterior fossa with no relation to the foramen magnum. Associated with hypoplasia.[5][13] Not compatible with life [5] Other conditions sometimes associated with Chiari Malformation include hydrocephalus,[14] syringomyelia, spinal curvature, tethered spinal cord syndrome, and connective tissue disorders[8] such as Ehlers-Danlos syndrome and Marfan Syndrome. Chiari malformation is the most frequently used term for these types of malformations. The use of the term Arnold–Chiari malformation has fallen somewhat out of favor over time, although it is used to refer to the type II malformation. Current sources use "Chiari malformation" to describe four specific types of the condition, reserving the term "Arnold-Chiari" for type II only.[15] Some sources still use "Arnold-Chiari" for all four types.[16] This article uses the latter convention. Chiari malformation or Arnold–Chiari malformation should not be confused with Budd-Chiari syndrome,[17] a hepatic condition also named for Hans Chiari. Brain Sagging and Pseudo-Chiari Malformation. The displacement of the cerebellar tonsils into the spinal canal may be mistaken for a Chiari I malformation, and some patients with spontaneous intracranial hypotension have undergone decompressive posterior fossa surgery.[18]
- Arnold–Chiari malformation, or often simply Chiari malformation, is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils through the foramen magnum (the opening at the base of the skull), sometimes causing non-communicating [1] hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow.[2] The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain. It can cause headaches, fatigue, muscle weakness in the head and face, difficulty swallowing, dizziness, nausea, impaired coordination, and, in severe cases, paralysis.[3] Type I. A congenital malformation. Is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils.[5][6][7] Tonsillar ectopia of more than 3 mm below foramen magnum. Syringomyelia of cervical or cervicothoracic spinal cord can be seen. Sometimes the medullary kink and brainstem elongation can be seen. Syndrome of occipitoatlantoaxial hypermobility is an acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.[8] Patients who exhibit extreme joint hypermobility and connective tissue weakness as a result of Ehlers-Danlos syndrome or Marfan Syndrome are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation. This type is difficult to diagnose and treat.[9] Headache, Neck Pain, Unsteady gait usually during childhood [5] Type II. Usually accompanied by a lumbar myelomeningocele or lumbosacral spine with herniation of the vermis below the foramen magnum.[5][10] As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement. Low lying torcular herophili, tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.[11] The position of the torcular herophili is important for distinction from Dandy-Walker syndrome in which it is classically upturned. This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging. Colpocephaly may be seen due to the associated neural tube defect. Paralysis below the spinal defect [5] Type III. It is associated with an occipital encephalocele containing a variety of abnormal neuroectodermal tissues. Syringomyelia and tethered cord as well as hydrocephalus is also seen.[5][12] Causes abundant neurological deficits [5] Type IV. Characterized by a lack of cerebellar development in which the cerebellum and brain stem lie within the posterior fossa with no relation to the foramen magnum. Associated with hypoplasia.[5][13] Not compatible with life [5] Other conditions sometimes associated with Chiari Malformation include hydrocephalus,[14] syringomyelia, spinal curvature, tethered spinal cord syndrome, and connective tissue disorders[8] such as Ehlers-Danlos syndrome and Marfan Syndrome. Chiari malformation is the most frequently used term for these types of malformations. The use of the term Arnold–Chiari malformation has fallen somewhat out of favor over time, although it is used to refer to the type II malformation. Current sources use "Chiari malformation" to describe four specific types of the condition, reserving the term "Arnold-Chiari" for type II only.[15] Some sources still use "Arnold-Chiari" for all four types.[16] This article uses the latter convention. Chiari malformation or Arnold–Chiari malformation should not be confused with Budd-Chiari syndrome,[17] a hepatic condition also named for Hans Chiari. Brain Sagging and Pseudo-Chiari Malformation. The displacement of the cerebellar tonsils into the spinal canal may be mistaken for a Chiari I malformation, and some patients with spontaneous intracranial hypotension have undergone decompressive posterior fossa surgery.[18]
- Syringomyelia ( /sɪˌrɪŋɡɵmaɪˈiːliə/) is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in pain, paralysis, weakness,[1] and stiffness in the back, shoulders, and extremities. Syringomyelia may also cause a loss of the ability to feel extremes of hot or cold, especially in the hands. The disorder generally leads to a cape-like loss of pain and temperature sensation along the back and arms. Each patient experiences a different combination of symptoms. These symptoms typically vary depending on the extent and, often more critically, to the location of the syrinx within the spinal cord. Syringomyelia has a prevalence estimated at 8.4 cases per 100,000 people,[2] with symptoms usually beginning in young adulthood. Signs of the disorder tend to develop slowly, although sudden onset may occur with coughing, straining, or myelopathy. Congenital The first major form relates to an abnormality of the brain called an Arnold-Chiari malformation. This is the most common cause of syringomyelia, where the anatomic abnormality causes the lower part of the cerebellum to protrude from its normal location in the back of the head into the cervical or neck portion of the spinal canal. A syrinx may then develop in the cervical region of the spinal cord. Because of the relationship that was once thought to exist between the brain and spinal cord in this type of syringomyelia, physicians sometimes refer to it as communicating syringomyelia. Here, symptoms usually begin between the ages of 25 and 40 and may worsen with straining or any activity that causes cerebrospinal fluid pressure to fluctuate suddenly. Some patients, however, may have long periods of stability. Some patients with this form of the disorder also have hydrocephalus, in which cerebrospinal fluid accumulates in the skull, or a condition called arachnoiditis, in which a covering of the spinal cord—the arachnoid membrane—is inflamed. Some cases of syringomyelia are familial, although this is rare. Acquired The second major form of syringomyelia occurs as a complication of trauma, meningitis, hemorrhage, a tumor, or arachnoiditis. Here, the syrinx or cyst develops in a segment of the spinal cord damaged by one of these conditions. The syrinx then starts to expand. This is sometimes referred to as noncommunicating syringomyelia. Symptoms may appear months or even years after the initial injury, starting with pain, weakness, and sensory impairment originating at the site of trauma. The primary symptom of post-traumatic syringomyelia (often referred to using the abbreviation of PTS)[3] is pain, which may spread upward from the site of injury. Symptoms, such as pain, numbness, weakness, and disruption in temperature sensation, may be limited to one side of the body. Syringomyelia can also adversely affect sweating, sexual function, and, later, bladder and bowel control. A typical cause of PTS would be a car accident or similar trauma involving a whip-lash injury. What can make PTS difficult to diagnose is the fact that symptoms can often first appear long after the actual cause of the syrinx occurred, e.g. a car accident occurring and then the patient first experiencing PTS symptoms such as pain, loss of sensation, reduced ability on the skin to feel varying degrees of hot and cold, a number of months after car accident. [edit] Symptoms Syringomyelia causes a wide variety of neuropathic symptoms due to damage of the spinal cord. Patients may experience severe chronic pain, abnormal sensations and loss of sensation particularly in the hands. Some patients experience paralysis or paresis temporarily or permanently. A syrinx may also cause disruptions in the parasympathetic and sympathetic nervous systems, leading to abnormal body temperature or sweating, bowel control issues, or other problems. If the syrinx is higher up in the spinal cord or affecting the brainstem as in syringobulbia, vocal cord paralysis, ipsilateral tongue wasting, trigeminal nerve sensory loss, and other signs may occur.[4] Rarely, bladder stones can occur in the onset of weakness in the lower extremities.[5] Classically, syringomyelia spares the dorsal column/medial lemniscus of the spinal cord, leaving pressure, vibration, touch and proprioception intact in the upper extremities. Neuropathic arthropathy, also known as a Charcot joint, can occur, particularly in the shoulders, in patients with syringomyelia. The loss of sensory fibers to the joint is theorized to lead to damage of the joint over time.[6] Surgery The first step after diagnosis is finding a neurosurgeon who is experienced in the treatment of syringomyelia. Surgery is the only viable treatment for syringomyelia. Not all patients will advance to the stage where surgery is needed. Evaluation of the condition is often difficult because syringomyelia can remain stationary for long periods of time, and in some cases progress rapidly. Surgery of the spinal cord has certain, characteristic risks associated with it and the benefits of a surgical procedure on the spine have to be weighed against the possible complications associated with any procedure. Surgical treatment is aimed at correcting the condition that allowed the syrinx to form. It is vital to bear in mind that the drainage of a syrinx does not necessarily mean the elimination of the syrinx-related symptoms, but rather is aimed at stopping progression. In cases involving an Arnold-Chiari malformation, the main goal of surgery is to provide more space for the cerebellum at the base of the skull and upper cervical spine without entering the brain or spinal cord. This often results in flattening or disappearance of the primary syrinx or cavity, over time, as the normal flow of cerebrospinal fluid is restored. If a tumor is causing syringomyelia, removal of the tumor is the treatment of choice and almost always eliminates the syrinx. Surgery results in stabilization or modest improvement in symptoms for most patients. Delay in treatment may result in irreversible spinal cord injury. Recurrence of syringomyelia after surgery may make additional operations necessary; these may not be completely successful over the long term. In some patients it may also be necessary to drain the syrinx, which can be accomplished using a catheter, drainage tubes, and valves. This system is also known as a shunt. Shunts are used in both the communicating and noncommunicating forms of the disorder. First, the surgeon must locate the syrinx. Then, the shunt is placed into it with the other end draining cerebrospinal fluid (CSF) into a cavity, usually the abdomen. This type of shunt is called a ventriculoperitoneal shunt and is particularly useful in cases involving hydrocephalus. By draining syrinx fluid, a shunt can arrest the progression of symptoms and relieve pain, headache, and tightness. Without correction, symptoms generally continue. The decision to use a shunt requires extensive discussion between doctor and patient, as this procedure carries with it greater risk of injury to the spinal cord, infection, blockage, or hemorrhage and may not necessarily work for all patients. Draining the syrinx more quickly does not produce better outcomes, but a shunt may be required if the fluid in the syrinx is otherwise unable to drain. In the case of trauma-related syringomyelia, the surgeon operates at the level of the initial injury. The syrinx collapses at surgery but a tube or shunt is usually necessary to prevent re-expansion.
- Arnold–Chiari malformation, or often simply Chiari malformation, is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils through the foramen magnum (the opening at the base of the skull), sometimes causing non-communicating [1] hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow.[2] The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain. It can cause headaches, fatigue, muscle weakness in the head and face, difficulty swallowing, dizziness, nausea, impaired coordination, and, in severe cases, paralysis.[3] Type I. A congenital malformation. Is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils.[5][6][7] Tonsillar ectopia of more than 3 mm below foramen magnum. Syringomyelia of cervical or cervicothoracic spinal cord can be seen. Sometimes the medullary kink and brainstem elongation can be seen. Syndrome of occipitoatlantoaxial hypermobility is an acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.[8] Patients who exhibit extreme joint hypermobility and connective tissue weakness as a result of Ehlers-Danlos syndrome or Marfan Syndrome are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation. This type is difficult to diagnose and treat.[9] Headache, Neck Pain, Unsteady gait usually during childhood [5] Type II. Usually accompanied by a lumbar myelomeningocele or lumbosacral spine with herniation of the vermis below the foramen magnum.[5][10] As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement. Low lying torcular herophili, tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.[11] The position of the torcular herophili is important for distinction from Dandy-Walker syndrome in which it is classically upturned. This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging. Colpocephaly may be seen due to the associated neural tube defect. Paralysis below the spinal defect [5] Type III. It is associated with an occipital encephalocele containing a variety of abnormal neuroectodermal tissues. Syringomyelia and tethered cord as well as hydrocephalus is also seen.[5][12] Causes abundant neurological deficits [5] Type IV. Characterized by a lack of cerebellar development in which the cerebellum and brain stem lie within the posterior fossa with no relation to the foramen magnum. Associated with hypoplasia.[5][13] Not compatible with life [5] Other conditions sometimes associated with Chiari Malformation include hydrocephalus,[14] syringomyelia, spinal curvature, tethered spinal cord syndrome, and connective tissue disorders[8] such as Ehlers-Danlos syndrome and Marfan Syndrome. Chiari malformation is the most frequently used term for these types of malformations. The use of the term Arnold–Chiari malformation has fallen somewhat out of favor over time, although it is used to refer to the type II malformation. Current sources use "Chiari malformation" to describe four specific types of the condition, reserving the term "Arnold-Chiari" for type II only.[15] Some sources still use "Arnold-Chiari" for all four types.[16] This article uses the latter convention. Chiari malformation or Arnold–Chiari malformation should not be confused with Budd-Chiari syndrome,[17] a hepatic condition also named for Hans Chiari. Brain Sagging and Pseudo-Chiari Malformation. The displacement of the cerebellar tonsils into the spinal canal may be mistaken for a Chiari I malformation, and some patients with spontaneous intracranial hypotension have undergone decompressive posterior fossa surgery.[18]
- Arnold–Chiari malformation, or often simply Chiari malformation, is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils through the foramen magnum (the opening at the base of the skull), sometimes causing non-communicating [1] hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow.[2] The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain. It can cause headaches, fatigue, muscle weakness in the head and face, difficulty swallowing, dizziness, nausea, impaired coordination, and, in severe cases, paralysis.[3] Type I. A congenital malformation. Is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils.[5][6][7] Tonsillar ectopia of more than 3 mm below foramen magnum. Syringomyelia of cervical or cervicothoracic spinal cord can be seen. Sometimes the medullary kink and brainstem elongation can be seen. Syndrome of occipitoatlantoaxial hypermobility is an acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.[8] Patients who exhibit extreme joint hypermobility and connective tissue weakness as a result of Ehlers-Danlos syndrome or Marfan Syndrome are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation. This type is difficult to diagnose and treat.[9] Headache, Neck Pain, Unsteady gait usually during childhood [5] Type II. Usually accompanied by a lumbar myelomeningocele or lumbosacral spine with herniation of the vermis below the foramen magnum.[5][10] As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement. Low lying torcular herophili, tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.[11] The position of the torcular herophili is important for distinction from Dandy-Walker syndrome in which it is classically upturned. This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging. Colpocephaly may be seen due to the associated neural tube defect. Paralysis below the spinal defect [5] Type III. It is associated with an occipital encephalocele containing a variety of abnormal neuroectodermal tissues. Syringomyelia and tethered cord as well as hydrocephalus is also seen.[5][12] Causes abundant neurological deficits [5] Type IV. Characterized by a lack of cerebellar development in which the cerebellum and brain stem lie within the posterior fossa with no relation to the foramen magnum. Associated with hypoplasia.[5][13] Not compatible with life [5] Other conditions sometimes associated with Chiari Malformation include hydrocephalus,[14] syringomyelia, spinal curvature, tethered spinal cord syndrome, and connective tissue disorders[8] such as Ehlers-Danlos syndrome and Marfan Syndrome. Chiari malformation is the most frequently used term for these types of malformations. The use of the term Arnold–Chiari malformation has fallen somewhat out of favor over time, although it is used to refer to the type II malformation. Current sources use "Chiari malformation" to describe four specific types of the condition, reserving the term "Arnold-Chiari" for type II only.[15] Some sources still use "Arnold-Chiari" for all four types.[16] This article uses the latter convention. Chiari malformation or Arnold–Chiari malformation should not be confused with Budd-Chiari syndrome,[17] a hepatic condition also named for Hans Chiari. Brain Sagging and Pseudo-Chiari Malformation. The displacement of the cerebellar tonsils into the spinal canal may be mistaken for a Chiari I malformation, and some patients with spontaneous intracranial hypotension have undergone decompressive posterior fossa surgery.[18]
- Arnold–Chiari malformation, or often simply Chiari malformation, is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils through the foramen magnum (the opening at the base of the skull), sometimes causing non-communicating [1] hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow.[2] The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain. It can cause headaches, fatigue, muscle weakness in the head and face, difficulty swallowing, dizziness, nausea, impaired coordination, and, in severe cases, paralysis.[3] Type I. A congenital malformation. Is generally asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils.[5][6][7] Tonsillar ectopia of more than 3 mm below foramen magnum. Syringomyelia of cervical or cervicothoracic spinal cord can be seen. Sometimes the medullary kink and brainstem elongation can be seen. Syndrome of occipitoatlantoaxial hypermobility is an acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.[8] Patients who exhibit extreme joint hypermobility and connective tissue weakness as a result of Ehlers-Danlos syndrome or Marfan Syndrome are susceptible to instabilities of the craniocervical junction and thus acquiring a Chiari Malformation. This type is difficult to diagnose and treat.[9] Headache, Neck Pain, Unsteady gait usually during childhood [5] Type II. Usually accompanied by a lumbar myelomeningocele or lumbosacral spine with herniation of the vermis below the foramen magnum.[5][10] As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement. Low lying torcular herophili, tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.[11] The position of the torcular herophili is important for distinction from Dandy-Walker syndrome in which it is classically upturned. This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging. Colpocephaly may be seen due to the associated neural tube defect. Paralysis below the spinal defect [5] Type III. It is associated with an occipital encephalocele containing a variety of abnormal neuroectodermal tissues. Syringomyelia and tethered cord as well as hydrocephalus is also seen.[5][12] Causes abundant neurological deficits [5] Type IV. Characterized by a lack of cerebellar development in which the cerebellum and brain stem lie within the posterior fossa with no relation to the foramen magnum. Associated with hypoplasia.[5][13] Not compatible with life [5] Other conditions sometimes associated with Chiari Malformation include hydrocephalus,[14] syringomyelia, spinal curvature, tethered spinal cord syndrome, and connective tissue disorders[8] such as Ehlers-Danlos syndrome and Marfan Syndrome. Chiari malformation is the most frequently used term for these types of malformations. The use of the term Arnold–Chiari malformation has fallen somewhat out of favor over time, although it is used to refer to the type II malformation. Current sources use "Chiari malformation" to describe four specific types of the condition, reserving the term "Arnold-Chiari" for type II only.[15] Some sources still use "Arnold-Chiari" for all four types.[16] This article uses the latter convention. Chiari malformation or Arnold–Chiari malformation should not be confused with Budd-Chiari syndrome,[17] a hepatic condition also named for Hans Chiari. Brain Sagging and Pseudo-Chiari Malformation. The displacement of the cerebellar tonsils into the spinal canal may be mistaken for a Chiari I malformation, and some patients with spontaneous intracranial hypotension have undergone decompressive posterior fossa surgery.[18]