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DR . KA E L KE BI O 2 7 6

Arnold Chiari MalformationWith SyringomyeliaLeslie ManleyAPRIL 15, 2010

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Introduction to Chiari Malformation

In 1827, Charles Prosper Olivier d Angers published an article about disorders ofthe spinal cord. While working with cadavers he discovered cavities in the someof the specimens; since the cavities had no name he put two Greek words together, syrinx-meaning pipe and myelus-meaning marrow and came up with syringomyelia (Oro, 2003). In 1883, Dr. Cleland was the first to describe posterior-fossa abnormalities. In 1891, Dr. Hans Von Chiari described the anomaly as a hind brain deformity and described two types: type 1 anomaly, which was described as elongation of the cerebellar tonsils, and type 2, which depicted lengthening of the cerebellum and as well as an abnormality in the fourth ventricle. In 1907, students of Arnold described four more cases and tagged Arnolds name to the Chiari malformation. The current classification has evolved to four distinct types of Chiari Malformation (Mueller, April 2001) (History, 2005).

I picked Chiari Malformation (CM) with Syringomyelia (SM), because it has been apart of my life for the last seventeen years; my husband, Bill was diagnosed with CM with SM. What does this all-mean one author describes CM as brain stem conundrum (Mueller, April 2001). In non-technical language, it means the brain hasfallen out of the skull and being pinched by the vertebrae in the neck, with a cyst in the spinal cord. This is how CM was explained to us in the beginning.

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His CM was acute, the Neurosurgeon told him that if he did not have it done right away the onset of his CM would disable him permanently, and that he may not walk within three weeks. He had it done right away and was back to work in a week.

Anatomy and Physiology

Anatomy

The skull for protection surrounds the brain. The bottom of the skull has an opening called the foramen magnum, which lets blood vessels and nerves pass throughto the brain from the spinal area. The cerebellum, brainstem and the fourth ventricle lie within the posterior fossa, the base bone of the skull. The brainstemconnects the brain and the spinal cord through the foramen magnum; the vertebrae protect the spinal cord from injury. The top two vertebrae also called C1 theatlas that the skull articulates with and C2 the axis that helps us move our head from side to side (Oro, 2003).

Chiari malformation is divided and described into four different types.

Chiari I Malformation

Chiari I Malformation has traditionally been defined as a downward herniation of

the cerebellar tonsils through the foramen magnum, about three to five millimeters in length below the posterior occipital bone. This is commonly

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called adult Chiari malformation, presents in patients twenties or thirties (Mueller, April 2001).

Chiari II Malformation

Chiari II malformation, commonly known as pediatric Chiari malformation and is present at birth, consists of being a downward herniation of the lower cerebellumand the medulla into the spinal canal. Chiari II is associated with myelomeningocele and brainstem dysfunction can be linked to mental retardation in some cases (Green, August 2003) (Micheal Salman, 2009).

Chiari III Malformation

Chiari III malformation is also present at birth, as a cerebellar herniation into a cervical encephalocele, which is a protrusion of brain tissue through an abnormal hole in the skull or fissure in the skull (Thomas Milhort, 1999)

Chiari IV Malformation

Chiari IV malformation is considered an under developed brain known as cerebellar hypoplasia, this form is also present at birth. Today they believe that ChiariIV malformation is different from the other three and most specialists no longe

r consider it a type of Chiari malformation (Oro, 2003).

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Syringomyelia

Syringomyelia is an obstruction at the foramen magnum and cerebral spinal fluidcannot flow normally. This will cause CSF to build up inside of the spinal cord,this forms a syrinx (cavity). Can be caused by a spinal cord injury, tumor anddamage from inflammation around spinal cord (Staff, Syringomyelia, 2009).

Physiology

Chiari malformation is an unusual congenital neuroskeletal deformity, the exactpathogenesis and incidences of the disorder are unknown. Theories suggest that the malformation develops in the embryonic stage (Oro, 2003). Many researchers and specialists believe that Chiari malformation may result from an underdevelopedposterior occipital bone in the skull. The posterior fossa is too small and does not provide room for the cerebellum and lower brain stem. (Mueller, April 2001)

Signs and Symptoms

Many patients with Chiari malformation have no signs or symptoms and do not needto be treatment. Their condition is only detected when other tests are preformed for unrelated disorders (Staff, Chiari Malformation, 2008). Many times, it is

misdiagnosed because the symptoms are so common with other

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disorders. There are no measurable signs for Chiari malformation to help with diagnosis. X-ray can measure the length of the syrinx in the syringomyelia.

Symptoms can include:

Headache

Headaches being the most common symptom described by most patients these differfrom normal headaches. Chiari headaches start in the occipital region of the head radiating behind one eye region or both, then to the temporal region. Pain isdescribed more like a pressure inside the head than a traditional pain. These pains are amplified when coughing or sneezing. (Diane Mueller, March 2004)

Dizziness-Dysequilibrium-Weakness

The second most common symptom of Chiari is the feeling of lightheadedness and being dizzy, intermittently. Many suffer from dysequilibrium to the point of having unsteady gait and not being able to walk without falling frequently. Some being unstable enough to be wheel chair bound. This can tie in with weakness of thelower extremities, which patients also suffer from and many have weakness in their upper extremities too limiting activity. They often complain of tingling intheir extremities as well (Diane Mueller, March 2004).

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Pain

The most common pain noted was neck pain, with lack of range of motion describedas stiffness, dull aching, to the extreme of stabbing. Some patients feel burning or stabbing pain in their upper extremities and in the thoracic region, thisis most often associated with the syringomyelia. Patients that have extreme painalso had complaints of nausea (Diane Mueller, March 2004).

Neuro-Ophthalomologic Symptoms

Blurred vision was reported in patients ranging from inability to read small print or having the vision to drive. Chiari II effects eye movements because of theeffects that it has on the cerebellum; the vermis expands when compressed and spares some ocular motor functions. The ones without the expanded vermis experience abnormal eye movements. This was discovered while doing vision testing amonga few other tests like IQ, and cognitive functions (Micheal Salman, 2009).

Depression

Reports of patients having mild to severe depression and occurs in half of the patients with Chiari malformation. Many patients depression can be cured by antidepressants. Some patients experience severe enough depression to want to commit

suicide or attempt it. Some Chiari patients just have major anxiety.

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Neurological Problems

Chiari patients often suffer from neurological problems, varying from tingling in extremities to more serious such as seizures. Many experience radiating pain from different areas of the body mainly from their nerve tracts or unexplained itching. Some have memory loss as mild as forgetfulness to more serious problems such as forgetting where they live or knowing who they are. Facial numbness is problem for biting the tongue and not knowing how bad it is. Many Chiari patientshave loss of pain receptors, which can be very dangerous. They have problems swallowing and some wake up in the middle of the night choking with unknown reason.

Diagnosis and Prognosis

When assessing a patient with possible Chiari malformation, a thorough medical history and physical exam with emphasis on the neurological system such as Romberg, finger to nose, heel to shin, gait, rapid movements, hot, cold, light touch and pinprick sensations. They also may go through cranial nerve testing also. (Mueller, April 2001)

In the past, the only diagnosis was the physical, and made diagnosing Chiari malformation difficult. Today, diagnosing Chiari has become much easier

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with more up to date imaging devices, for example x-rays are clearer. Most hospitals and clinics have computerized tomography (CT), and magnetic resonance imaging (MRI) being the most popular choice for diagnosing CM. MRI gives the physician or specialist the most clear image, where they can measure syrinxes, how far distended the cerebellum is and what classification the patients Chari malformation, with or without syringomyelia.

Prognosis is usually good in CM patients, depending on the type and severity ofthe CM they have. Most patients, where there is neurological damage, usually recover their loss of feeling, and can go back to their life the way it was beforeCM set in. In very severe cases, patients do not recover well, some of the complications include hydrocephalous or paralysis. In Chiari IV, death is usually theprognosis or severe mental retardation due to under developed brain.

Treatments

Treatment I

The most common treatment for Chiari malformation is decompression surgery of the posterior fossa. It is also the treatment for most neurosurgeons to perform. Decompression surgery has a few different ways it can be done; with or without stabilization of neck and whether to use a duraplasty product, cadaver

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tissue or bovine mater. The objective of the surgery is to relieve the pressureon the cerebellar tonsils, brainstem and possible fourth ventricle, to enlarge the posterior fossa space and to normalize the flow of CSF.

The patient is prone position with a halo screwed into the head, to stabilize the head during surgery. A midline incision is made from the middle of the occipital bone to the base of C2 or C3, so that the surgeon has plenty of visual area of the skull. A craniectomy is preformed to expose the brain, cerebellum and brain stem. Lamination of C1 and C2 is done to give more visualization during surgery, which also helps when they need to shunt or sent to drain the spinal cord. The dura mater is carefully cut away, and replaced with a duraplasty graph or cadaver tissue that covers the cerebellar tonsils, the brainstem and the fourth ventricle to hold them in place. Some surgeons use electrocautery to shrink the tonsils. The graph also helps in regulation of the CSF flow (Frank Attenello, 2009).

The main complications of this surgery are CSF leakage, infection, septic meningitis, apnea and hydrocephalus. (ZQ Zhang, May 2008). Earlier patients that did not have a stabilization done or the fusion of C1 and C2; have complaints about the instability that they are experiencing. In some cases, the instability is sogreat they have to undergo tracheostomy ventilation, so that they can breathe (Fred Lam, 2009).

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Surgical procedure II for patient with a diagnosis of Chiari I malformation, itis a fairly new procedure, transoral odontectomy and suboccipital craniectomy, 2008, being done for treatment. This minimally evasive surgery is done through the open mouth. The incision extends from the inferior third of the clivus to thetop of C3. This facilitates the decompression of the cerebellar tonsils, the lower brainstem and the spinal cord. Therefore, there is minimal removal of the atlas arch and occipital bone, which makes reconstructive surgery less complicated,since most of the bones are there for them to work with. There construction makes for greater cranial movement after surgery (Steven Hwang, 2008)

Treatment II

Drug therapies, patients that present with headaches from physical strain or theclassic cough headache from Chiari. The first drug was Acetazolamide; clients taking this had rapid response to this drug and were relieved of their headaches.The medication relieves the inner cranial pressure and depresses the excitability of the neurons. The second drug Indomethacin had very similar results.

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My opinion of the treatments I have found, my first opinion would have been to go with the decompression, craniectomy surgery with stabilization for someone that also has syringomyelia. After reading about the transoral odontiodectomy and suboccipital craniectomy, I believe this would be my recommendation for someone with Chiari malformation without syringomyelia. It is less evasive than the traditional surgery, and the patients quality of life would be much better because theyhave more cervical movement with the transoral odontiodectomy.

I would not recommend the drug treatment programs because, in the end who knowswhat can happen. I would think from learning what I have about drugs that the body would become immune to these, because they alter, the neurons and blood flowso they would have the same effect as other drugs they quit working and the bodyneeds more to function.

Conclusion

Dr. Hans Von Chiari discovered these deformities over a century ago, and to think how far technology has progressed in diagnosing diseases, going from examiningcadavers in hiding to the imaging devices we have today. He may not have knownhow to fix his discoveries, but his name was still given to the deformity.

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Although, even today people go without treatment for Chiari malformation, because it can present itself in many ways often being misdiagnosed, the MRI is the only true way to diagnose Chiari. I believe that after being diagnosed that surgery be done as soon as possible, there is no time frame for Chiari it can strike at any time in life and the onset can be acute or very slow over time.

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References

Attenello, F., McGirt, M., Garces-Ambrssi, G., Chaichana, K., Carson, B., & Jallo, G. (2009). Suboccipital decompression for Chiari 1 Malformation:outcome comparison of duraplasty with expanded polytetrafluoroethylene dural subsitute versuspericranial autograft. Childs Nervous System, 25(2), 183-190. Retrieved from Ebscohost database. Green, A. (2006, July/August). Update on Chiari Malformation: Clinical Manifestations, Diagnosis, and Treatments. Pediatric Nursing, 29(4). Retrieved from Ebscohost database. Hwang, S., Heilman, C., Riesenburger, R., & Kryzanski, J. (2008). C1-C2 arthodesis after transoral odontoidectomy and suboccipital craniectomy for ventral brain stem compression in Chiari 1 patients. EuropeanSpine Journal, 17, 1211-1217. Retrieved from Ebscohost database. Lam, F., Irvin,B., Poskitt, K., & Stienbok, P. (2009). Cervical spine instability following cervical laminectomies for Chiari 2 Malformation: a retrospective cohort study. Childs Nervous System, 25(1). Retrieved from Ebscohost database. Mayo Clinic Staff.(2009, February 19). Syringomyelia Definition. In Syringomyelia Definition. Retrieved from http://www.mayoclinic.com/health/syringomyelia/ DS01127

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Milhort, T., Chou, M., Trinidad, E., Kula, R., Mandell, M., Wolpert, C., & Speer, M. (1999, May). Chiari 1 Malformation Redifined: Clinical and Radiogrphic Findings for 364 Symptomatic Patients. Nuerosurgery Online, 44(5), 1005-1017. Retrieved from Ovid database. Mueller, D. (2001, April). Brain Stem Conumdrum: Chiari1 Malformation. Journal of the Academy Of Nurse Practitioners, 13(4). Retrievedfrom Ebscohost database. Mueller, D., & Oro, J. (2004, March). Prospective Analysis of Presenting Symtoms Among 265 Patients With Radiographic Evidence of ChiariMalformation. Journal of Nurse Practitioners, 16(3), 134-138. Retrieved from Ebscohost database. Oro, J. (2003). Chiari & Syrigomyelia. In American Syringomyelia Alliance Project Confrence (pp. 1-7). Retrieved from Ebscohost database. Salman, M., Dennis, M., & Sharpe, J. (2009, November). The cerebellar dysplasia of Chiari II Malformation as revealed by eye movements. The Canadian Journal of Neurological Sciences, 36(3), 713-724. Retrieved from Ebscohost database. Staff. (2005). History. In UW Medicine-Chiari Malformation Clinic [History Web page]. Retrieved April 12, 2010, from Ebscohost database. Staff. (2008, November 13). ChiariMalformation-MayoClinic. In Chiari Malformation. Retrieved March 24, 2010, fromMayo Foundation for Medical Education and Research website: http://www.mayoclinic.com/health/chiari-malformation/ DS00839

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Zhang, Z., Chen, Y., Chen, Y., Wu, X., Wang, Y., & LI, X. (2008, May). Chiari 1malformation assoiated with syringomyelia: a retrospective study 316 surgicallytraeted patients. Spinal Cord, 46(5), 358-363. Retrieved from Ebscohost database.

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