Visual Consequences of u Which cause of Chiari malformation is not - PDF document

James Kundart OD MEd FAAO FCOVD- A Learning Objectives u Which cause of Chiari malformation is most common? What are the presenting symptoms? Visual Consequences of u Which cause of Chiari malformation is not evident with imagining, but may have ocular Chiari Malformation signs and symptoms? u What are the differential diagnoses for Chiari syndrome? 2018 VICTORIA CONFERENCE JAMES KUNDART OD MED FAAO FCOVD-A u What are the surgical and non- surgical treatments for Chiari PACIFIC UNIVERSITY COLLEGE OF OPTOMETRY malformation? FINANCIAL DISCLOSURE: NOTHING TO DISCLOSE https://www.conquerchiari.org/index.html https://en.wikipedia.org/wiki/Hans_Chiari http://www.ajnr.org/content/34/5/919.long Evidence of Chiari in Definition of Europe Dates to 16 th -17 th Chiari Malformation Centuries u Chiari malformation is traditionally defined as the cerebellar tonsils being located 3mm-5mm or more below the foramen magnum as https://www.ncbi.nlm.nih.gov/ measured on an MRI pubmed/25192779 https://www.conquerchiari.org/documents/presentations /OVERVIEW%20Presentation.pdf Problems with the Alternative Definitions: Traditional Chiari Definition Twining and Chamberlain Lines u Some people have large herniations with no symptoms u Others have only small herniations, but are severely symptomatic http://stroke.ahajournals.org/ content/31/9/2062 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ 1

James Kundart OD MEd FAAO FCOVD- A Chiari Symptoms: Variable Symptoms of Pressure Behind the Eyes Chiari Malformation https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4508727/pdf/nmc-53-847.pdf https://www.conquerchiari.org/documents/prese ntations/SYMPTOMS%20Presentation.pdf Chiari Signs: Brainstem Compression in C/D ratio decrease also! Chiari Malformation https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4508727/pdf/nmc-53-847.pdf https://www.conquerchiari.org/documents/prese ntations/SYMPTOMS%20Presentation.pdf Causes of Chiari: High CSF-Pressure Chiari, Increased CSF Pressure “Type 0” (same as IIH?) u Chiari doesn’t require obstruction, just higher CSF pressure u This is controversially called Chiari, Type 0 u It resembles idiopathic intracranial hypertension (IIH), and may be indistinguishable from it One of my first Chiari suspects – https://en.wikipedia.org/wiki/Chiari_malformation Where is the foramen magnum? 2

James Kundart OD MEd FAAO FCOVD- A Causes of Chiari: Causes of Chiari: Small Posterior Fossa Connective Tissue Disorders u This is the default u “There is one published large study that has looked at the “anatomical association between type 1 determinism” theory Chiari and EDS u When this occurs, u This was undertaken by transient but recurrent Milhorat et. al. in 2007 at The Chiari Institute in New York hydrocephalus can u They looked at 2813 patients result with a known diagnosis of u In these cases, surgery Chiari malformation, Type I may be the best u They found that 357 (12-13%) option had features of EDS ” https://en.wikipedia.org/wiki/Posterior_cranial_fossa Causes of Chiari: Syrinxes and Tethered Cord (?) Syringomyelia u “Tethered cord is a relatively u A syrinx is a fluid- new entity, medically filled cyst in the speaking, and as such there is spinal cord still quite a bit of controversy surrounding it u This causes spinal u There is even occult tethered cord edema, compromising cord, since the tethering is not always apparent on MRI neuronal function u A second area of controversy u Permanent nerve involves the relationship, if damage can result, any, between tethered cord but they are easily and Chiari and/or missed with MRI of https://www.ncbi.nlm.nih.gov/pmc syringomyelia”, or syrinxes the head only /articles/PMC5738018/ https://www.conquerchiari.org/documents/presentations /OVERVIEW%20Presentation.pdf Spinal Cord Syrinxes Normal vs. Chiari and Chiari Symptoms Cerebellum & Syrinx http://www.mayfieldclinic.com/PE-Chiari.htm http://www.mayfieldclinic.com/PE-Chiari.htm#.VXiR486VzPA 3

James Kundart OD MEd FAAO FCOVD- A How Common is Chiari? Chari Commonalities: The Low Obex and Small Posterior Fossa Mimicking by IIH u The US Association of Neurological neurological surgeons performs 10K Chiari surgeries per year u Chiari may be as common as 1:1000 patients in the US. Also… u “Cerebellar tonsil position in patients with IIH was significantly lower than that in age-matched https://en.wikipedia.org/wiki/ controls, oftentimes peg- https://www.ncbi.nlm.nih.gov/ https://en.wikipedia.org/wiki/Obex Posterior_cranial_fossa like, mimicking Chiari ” pmc/articles/PMC4054396/ Gender and Ethnic Trends Three Types of Chiari in Chiari Malformation Chiari 1. u Chiari is often diagnosed in Malformation, young adults Type I u Female patients get Chiari more often than male patients Arnold-Chiari 2. u It affects all ethnicities and Malformation body mass indices Chiari 3. u Retrobulbar optic nerve Malformation, tortuosity is common and often Type III asymptomatic, as shown here https://en.wikipedia.org/wiki/Chiari_malformation https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ Three Types of Chiari Classical Chiari Type I u Mid-sagittal section MRI is the best way to diagnose the structural component of Chiari malformation, but depends on where the foramen magnum is placed u Sometimes, coronal MRI is the best way to see cerebellar tonsillar herniation (right) Wong, page 170 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ 4

James Kundart OD MEd FAAO FCOVD- A Congenital Chiari Type I Arnold-Chiari (Type II) u Much less common than u (a) Axial T2W MRI shows Type I, this birth defect leads crowding at the level of to fourth ventricle the foramen magnum hydrocephalus with herniation of the cerebellar tonsils (arrow) u Expect childhood-onset with more severe symptoms u (b)Sagittal T1W MRI shows caudal herniation of the u Surgical intervention is highly “peg shaped” cerebellar likely tonsils (arrow) u Type II is the only time this u (c) Sagittal T2W MRI of a malformation is properly different patient shows called Arnold-Chiari associated syringomyelia https://www.ncbi.nlm.nih.gov/ (arrowheads) pmc/articles/PMC4757284/ http://www.fluidsbarrierscns.com/content/5/1/2/figure/F2?highres=y Congenital Arnold-Chiari, Chiari, Type III Type II u Chiari II malformation. u This terrible birth defect (a)Sagittal T1W MRI shows a is characterized by small posterior fossa with a cerebellar herniation low torcular insertion outside the skull cavity, (arrow) and tectal beaking called an (arrowhead) encephalocele u (b) Axial T2W MRI fails to u This happens when the demonstrate the neural tube does not cerebellum between the close during the first occipital lobes trimester of gestation u (c) T2W MRI shows spinal u Various teratogens like dysraphysm*, or a neural arsenic can cause this tube defect usually fatal condition https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4757284/ http://radiopaedia.org/articles/chiari-ii-malformation Chiari Type III is Congenital Visual Symptoms of Chiari u These patients are often born with u Blurred vision paraplegia due to the CNS myelo- u Diplopia and meningocele strabismus u This non-ambulatory patient may also be u Nystagmus nonverbal as the u Photophobia cerebellum controls coordination of the u Visual field tongue as well as the defects eyes and limbs https://www.conquerchiari.org/documents/prese https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4757284/ ntations/SYMPTOMS%20Presentation.pdf 5

James Kundart OD MEd FAAO FCOVD- A Chiari Ocular Motility in Chiari Malformation, Diplopia, and Strabismus Mild cases of u Chiari may result in intermittent diplopia Often, this presents u as esotropia at far of the divergence insufficiency type When this occurs, u suspect CN VI palsy Leigh & Zee, 5 th edition https://timroot.com/ophthobook/ Why Pursuits and Saccades OCT of 52 YOF with IIH (?) Are Affected in Chiari and Chiari Malformation Notice the absent optic cup and nerve fiber layer thickening https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ https://www.ncbi.nlm.nih.gov/pubmed/22864131 Baseline Visual Fields in 1-Month Post Tx Visual Chari, Type I: Expected? Fields in Chari, Type I https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ 6

James Kundart OD MEd FAAO FCOVD- A 3-Months Post Tx Visual 6-Months Post Tx Visual Fields in Chari, Type I Fields: Notice Blind Spot OS https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ 12-Months Post Tx Visual Differential Diagnoses Fields in Chari, Type I That Mimic Chiari https://www.conquerchiari.org/documents/prese https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054396/ ntations/DIAGNOSIS%20Presentation.pdf Treatment: Syrinxes & Surgery Chiari Obscured by Morning Glory Disc https://www.ncbi.nlm.nih.gov/pubmed/24802674 https://www.ncbi.nlm.nih.gov/pubmed/14966661 7