Spinal Cord Diseases or Disorders
- 1. Arachnoiditis
- 2. Arterial-venous Malformation
- 3. Brown-Sequard Syndrome
- 4. Cauda Equina Syndrome
- 5. Central Cord Syndrome
- 6. Guillain-Barré Syndrome
- 7. Back and spine conditions/disorders (see Health & Wellness)
- 8. Multiple sclerosis
- 8.1. Multiple Sclerosis Coalition
- 8.2. MS Survey-Mental Health Assistance
- 8.3. Economics of Living with Multiple Sclerosis
- 8.4. Alternative Medicine and MS
- 8.5. Multiple sclerosis information sheets and organizations
- 8.6. MS and spasticity
- 8.7. MS and Vitamin D
- 8.8. MS Coalition-Disease Modifying Therapy
- 9. Polio/post Polio
- 10. Spinal Cord Tumor
- 11. Spina Bifida
- 12. Spinal Muscular Atrophy
- 13. Spinal Stenosis
- 14. Stroke/spinal
- 15. Syringomyelia
- 16. Tarlov Cysts
- 17. Transverse Myelitis
1.1. Arachnoiditis information sheets and on-line support
Circle of Friends with Arachnoiditis (on Pinterest)
An online support group site for those who suffer from or know someone with arachnoiditis. COFWA trys to provide education, friendship, caring, sharing, and insights and assist with questions about arachnoiditis.
NIH, National Institute of Neurological Disorders and Stroke (NINDS) Arachnoiditis Information Page.
2. Arterial-venous Malformation
2.1. Arteriovenous Malformation information sheet
Arteriovenious Malformation information page from NINDS
Arteriovenous information and treatment at Cleveland Clinic
3. Brown-Sequard Syndrome
3.1. Brown-Sequard information
3.2 NORD (National Organization for Rare Disorders) Brown-Sequard Patient Information Sheet
3.2. Brown-Sequard articles
4. Cauda Equina Syndrome
4.1. Cauda Equina Syndrome Fact Sheet
A Cauda Equina Syndrome Fact Sheet produced by the American Academy of Orthopedic Surgeons.
5. Central Cord Syndrome
5.1. Central Cord Syndrome information
Central Cord Syndrome information page from NINDS
5.2. Info from AANS
Information from the American Association of Neurological Surgeons
6. Guillain-Barré Syndrome
6.1. Guillain-Barré Syndrome
Guillain-Barré Syndrome information page from National Institute of Neurological Disorders and Stroke (NINDS)
GBS/CIDP Foundation International, a global non-profit organization supporting individuals and their families affected by Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and related syndromes through a commitment to support, education, research, and advocacy.
375 East Elm Street
Conshohocken, PA 19428
Tel: 610-667-0131; 866-224-3301
7. Back and spine conditions/disorders (see Health & Wellness)
8. Multiple sclerosis
8.1. Multiple Sclerosis Coalition
United Spinal Association is among eight (8) member organizations of the Multiple Sclerosis Coalition
Mission: The Multiple Sclerosis Coalition's mission is to increase opportunities for cooperation and provide greater opportunity to leverage the effective use of resources for the benefit of the MS community.
Vision: To improve the quality of life for those affected by MS through a collaborative network of independent MS organizations.
Purpose: he Multiple Sclerosis Coalition (MSC) was founded in 2005 by three independent multiple sclerosis (MS) organizations in an effort to work together to benefit individuals with MS. Since that time, the MSC has grown to eight member organizations, all of whom provide critical MS programs and services.
The vision of the MSC is to improve the quality of life for those affected by MS through a collaborative national network of independent MS organizations. Our mission is to increase opportunities for cooperation and provide greater leverage in collaborative and effective use of resources for the benefit of the entire MS community.
The primary objectives of the MSC are to educate, advocate, collaborate, and improve the efficiency of services for individuals with MS and those who are close to them. With so much on the horizon in terms of MS research, treatments, advocacy, and symptom management, the MSC provides critical momentum to work together to enhance these exciting MS initiatives and to ensure this collective support continues.
3 University Plaza Drive, Suite 116
Hackensack, NJ 07601
Fax: (862) 772-7275
8.2. MS Survey-Mental Health Assistance
We know that mental health assistance is critical for many individuals living with MS across the country. United Spinal appreciates your valuable assistance in helping us find out more about the problems and issues you face in your community about accessing mental health assistance.
8.3. Economics of Living with Multiple Sclerosis
8.4. Alternative Medicine and MS
Alternative Medicine and MS (See preview) is a single source for accurate and unbiased information on the many complementary and alternative medicines that can help manage some MS symptoms and promote general health. Readers will be able to: * find unconventional options for therapy; * learn of potentially dangerous interactions between alternative therapies and medical treatments; * identify therapies that are effective, low risk, and inexpensive; * recognize ineffective, dangerous, or costly alternative therapies. A section on Integrating Conventional and Unconventional Medicine links specific symptoms to potentially useful alternative therapies: If readers have, for example, spasticity or bladder problems,
8.5. Multiple sclerosis information sheets and organizations
Multiple sclerosis information page from NINDS
National MS Society
Help each person address the challenges of living with MS through our 50-state network of chapters. The Society helps people affected by MS by funding cutting-edge research, driving change through advocacy, facilitating professional education, and providing programs and services that help people with MS and their families move their lives forward.
Multiple Sclerosis Foundation
Resources assist people who have MS, their families and caregivers, regional support groups, and healthcare professionals. Access to our programs and services is available through our interactive web site or our national, toll-free helpline staffed by caring caseworkers and peer counselors. Our priority is to serve with empathy, resourcefulness and responsibility. All MSF services, as well as information, literature and subscriptions to our publications are provided free of charge. Provides peer counseling, assistive technology program, homecare and computer grants.
Multiple Sclerosis Association of America
MSAA offers a variety of programs and services in all 50 states: Helpline consultations, equipment distribution, MRI diagnostic funding, resource assistance, and public awareness campaigns. MSAA also provides valuable information on the disease and symptom management through its award-winning literature and educational videos.
8.6. MS and spasticity
Multiple Sclerosis-Related Specificity: Answers for You and Your Loved Ones (download attached document)
This brochure was developed specifically for people living with multiple sclerosis and their loved oneswho want to learn more about spasticity. Questions and issues covered in this helpful and informative brochure include:
- What is spasticity?
- How do I know I have spasticity?
- Will I develop spasticity?
- Spasticity can cause different types of problems
- Why is detection of spasticity important?
- What should I do if I think I may have spasticity?
- How can I prepare for a discussion about spasticity treatment with my specialist?
8.7. MS and Vitamin D
Healthline has an interactive tool that shows the correlation between sun exposure, vitamin D, and MS rates.
8.8. MS Coalition-Disease Modifying Therapy
Please see the attached MS Coalition Disease Modifying Therapy paper. And, visit MS Coalition for more details.
3 University Plaza Drive, Suite 116
Hackensack, NJ 07601
Fax: (862) 772-7275
The National MS Society and the other member organizations of the MS Coalition have collaborated to produce a consensus document to summarize current evidence about disease modification and provide support for broad access to FDA-approved DMTs. This evidence-based document may be useful when addressing insurance questions (preauthorization, formulary, etc.); a companion piece for general audiences is currently under development.
Initiation of treatment with an FDA-approved DMT is recommended:
- As soon as possible following a diagnosis of relapsing MS
- For individuals with a first clinical event and MRI features consistent with MS, where other possible causes have been excluded
- For individuals with secondary-progressive multiple sclerosis who continue to demonstrate clinical relapses and/or demonstrate inflammatory changes
Treatment with any given DMT should be continued indefinitely unless any of the following occur:
- Sub-optimal treatment response as determined by the individual and the clinician
- Intolerable side effects or inadequate adherence
- Availability of a more appropriate treatment
The factors affecting choice of treatment are complex and most appropriately addressed by the individual in collaboration with the treating clinician. Movement from one DMT to another should occur only for medically appropriate reasons.
Due to significant variability in the MS population, people with MS and their clinicians require full access to a range of treatment options:
- Different mechanisms of action allow for treatment change in the event of sub-optimal response.
- Potential contraindications limit options for some individuals
- Risk tolerance varies among people with MS and their clinicians
- Route of delivery and side effects may affect adherence
- Individual differences related to tolerability and adherence may necessitate access to different medications within the same class
Access to treatment should not be limited by the patient's frequency of relapses, level of disability, age, gender or ethnicity. Absence of relapses while on treatment should not be considered a justification for discontinuation of treatment. Treatment should not be discontinued to allow for determination of coverage by payers.
9. Polio/post Polio
10. Spinal Cord Tumor
10.1. Spinal Cord Tumor-General Information & Support
National Institute of Neurological Disorders and Stroke (NINDS)- Brain and Spinal Tumors Information Page, provides information regarding brain and spinal cord tumor diagnosis, treatment, and research.
Mayo Clinic - Spinal Cord Tumor Information Page regarding spinal cord tumor symptoms, causes, diagnosis, and treatment.
Spinal Cord Tumor Association (SCTA) is a not-for-profit organization formed by spinal cord tumor survivors for the purpose of supporting survivors and their families. They offer informational materials and an online discussion board.
11. Spina Bifida
11.1. Intro to Spina Bifida
Spina Bifida, the most common neural tube defect (NTD), is one of the most devastating of all birth defects. It results from the failure of the spine to close properly during the first month of pregnancy. In severe cases, the spinal cord protrudes through the back and may be covered by skin and a thin membrane. Surgery to close a newborn's back is generally performed within 24 hours after birth to minimize the risk of infection and to preserve existing function in the spinal cord.
Because of the paralysis resulting from the damage to the spinal cord, people born with spina bifida may need surgeries and other extensive medical care. The condition can also cause bowel and bladder complications. A large percentage of children born with spina bifida also have hydrocephalus, the accumulation of fluid in the brain. Hydrocephalus is controlled by a surgical procedure called "shunting" which relieves the fluid build up in the brain by redirecting it into the abdominal area.
Types of Spina Bifida:
- Spina Bifida Occulta: This is a mild form of spina bifida which is very common. Estimates vary but between 5% and 10% of people may have spina bifida occulta. There is an opening in one or more of the vertebrae (bones) of the spinal column without apparent damage to the spinal cord.
- Meningocele: The meninges, or protective covering around the spinal cord, has pushed out through the opening in the vertebrae in a sac called the "meningocele". However, the spinal cord remains intact. This form can be repaired with little or no damage to the nerve pathways.
- Myelomeningocele: This is the most severe form of spina bifida in which a portion of the spinal cord itself protrudes through the back. In some cases, sacs are covered with skin; in others, tissue and nerves are exposed.
Preventing Spina Bifida:
Recent studies have shown that one factor that increases the risk of having and NTD baby is the low folic acid (a common water-soluble B vitamin, essential for the functioning of the human body) status before conception and during the first few weeks of pregnancy. If women consume 0.4 mg of folic acid prior to becoming pregnant and during the first trimester of pregnancy, the incidence of folic acid preventing spina bifida can be reduced by up to 75%.
Children with spina bifida need to learn mobility skills, and often with the use of crutches, braces, or wheelchairs can achieve more independence. Also, with new techniques children can become independent in managing their bowel and bladder problems. Physical disabilities like spina bifida can have profound effects on the child's emotional and social development. It is important that healthcare professionals, teachers, and parents understand the child's physical capabilities and limitations. To promote personal growth, they should encourage children to be independent, to participate in activities with their non-disabled peers and to assume responsibility for their own care.
11.2. Spina Bifida resources
Spina Bifida information page from NINDS
11.3. Spina Bifida-A Personal Perspective
By Kelly Rouba
Jennifer Biggers (left) and Amy Saffell both have the same type of spina bifida, but every person's condition is unique.
I first met Karen Palazzini in freshman year of high school. Although one might guess that our similar situations bonded us together, having a disability was something we rarely discussed. Instead, it was the countless chocolate desserts and sappy chick flicks-not her struggle with spina bifida or my battle with arthritis- that paved the way to friendship.
So, it wasn't until I took on this assignment that I finally asked Karen to share with me exactly what it means to have spina bifida. Now, 13 years later, I finally have the answer.
Spina Bifida-the Basics
To put it simply, "Spina bifida is a birth defect," Karen told me during a recent girls' night out. From there, things get a bit more complicated.
Spina bifida takes three forms-occulta, meningocele, and myelomeningocele. In each case, "the spinal cord in the fetus develops within the first 28 days of pregnancy," says Amanda Darnley, director of Communications and Marketing for the Spina Bifida Association, "Spina bifida occurs when the spine fails to close."
Occulta, the least severe of the forms, is the result of a small defect or gap in several vertebrae. Occulta is often referred to as the "hidden spina bifida" because motor or sensory impairments are not evident at birth. In most cases, there are no symptoms, however neurologic deterioration can develop later in life.
The second type, meningocele, means that the meninges (or membranes that cover the central nervous system) are protruding from a hole in the spinal cord. Although the nerves usually aren't damaged, individuals may suffer minor health problems.
Myelomeningocele is the most severe of the three and means that individuals have a hole (or lesion) in their spinal cord where the nerves don't connect. If the lesion is lower on the spinal cord, it usually means the person will have a less severe case of spina bifida.
"[Myelomeningocele] usually results in some sort of paralysis in the legs and it is common to see some sort of bowel and bladder control difficulties," Darnley said, adding, "With the bladder issues, people often end up having to catheterize, which can result in urinary tract infections."
Additionally, up to 90% of children who have myelomeningocele will experience hydrocephalus, which occurs when cerebrospinal fl uid builds up inside the head. "So [doctors] insert a shunt and it drains the fluid off the brain. The shunt is something [patients] will monitor their entire lives," Darnley said.
Amy Saffell, another friend of mine who was also born with spina bifida and relies on a wheelchair for mobility, pointed out that having spina bifida is not like having a typical spinal cord injury.
"Although the paralysis may be the same," Amy told me, "one big difference is that our body grows up knowing how to compensate. Many people with spinal cord injuries have bad muscle spasms and take lots of medicine to regulate their body since it has to operate totally differently from when they were able bodied. With spina bifida, we don't really have to do that because our body is totally used to being paralyzed; it's always been that way."
<strong>The Personal Side of Spina Bifida </strong>
"Spina bifida occurs in seven out of every 10,000 live births in the United States. And no two cases of spina bifida are ever the same. Every case is unique," Darnley says.
Karen has myelomeningocele, but her situation is not quite as severe as Amy's or another friend Jennifer Biggers. Now 23 years old, Jennifer has relied on a wheelchair for much of her life.
"I got my first wheelchair when I was four; it was right before preschool," Jennifer said. "Until then, I was carried everywhere. I also used braces when I was younger, mainly for exercise, but it was tiring because I don't have any muscle strength to hold me up."
Studies suggest a correlation between folic acid intake in a mother's diet and the incidence of spina bifida in her offspring. Doctors advise women of child-bearing age to eat diets rich in folic acid.
"Most children with spina bifida will have multiple surgeries throughout their childhood," Darnley says. "There are lots of different surgeries that are done."
Over the years, Karen has had about 10 operations. "My first surgery was when I was two months old and doctors basically operated to stabilize my spinal cord," she said. "Another time, I had a pin put in my hip to try to stabilize that joint. Because of the spina bifida, there was nerve damage in my right leg and the joints and bones didn't form right."
Jennifer's first surgery took place soon after she was born. "I had a hole in my back so I had to get that sewn up," she said. Later on, doctors "put a shunt in [my head], but it never worked and I never needed it. I guess it was a precautionary thing. It ended up swelling, so they took it out. I also have rods in my back now because I had scoliosis when I was younger."
Is There a Cure?
To date, the exact cause of spina bifida is still unknown. "Many things can affect a baby, from family genes to things a woman may have come in contact with during pregnancy," Darnley said.
There is also no cure for spina bifida. However, doctors are now experimenting with an in-utero surgery that might help babies who have the defect, Karen said. In the study, doctors are looking at the benefits of closing the lesion before the baby is born. Typically, doctors will operate after the baby is born.
It has also been found that the B-vitamin folic acid can be used as a preventative measure against spina bifida. According to Darnley, there was a signifi cant decrease in the number of cases of spina bifida when manufacturers started fortifying cereals and fl our by putting folic acid in them. "But, we still see a high level of occurrence (of spina bifida) in the Hispanic population," she noted.
"A lot of doctors say spina bifida results because of the lack of folic acid in the mother, but honestly it could just happen. My mother was healthy and taking everything she was supposed to," Jennifer added.
But, Darnley still advises, "Anyone who is of a child-bearing age should be taking a daily multivitamin. A normal woman should take 400 micrograms of folic acid each day, and those who have had a previously affected pregnancy, a doctor will put them on a prescription of a higher dose."
12. Spinal Muscular Atrophy
12.1. Muscular Distrophy Association-SMA
Spinal muscular atrophy (SMA) is a genetic disease affecting the part of the nervous system that controls voluntary muscle movement.
Most of the nerve cells that control muscles are located in the spinal cord, which accounts for the word spinal in the name of the disease. SMA is muscular because its primary effect is on muscles, which don't receive signals from these nerve cells. Atrophy is the medical term for getting smaller, which is what generally happens to muscles when they're not active.
SMA involves the loss of nerve cells called motor neurons in the spinal cord and is classified as a motor neuron disease.
In the most common form of SMA (chromosome 5 SMA, or SMN-related SMA), there is wide variability in age of onset, symptoms and rate of progression. In order to account for these differences, the chromosome 5 SMA often is classified into types 1 through 4.
The age at which SMA symptoms begin roughly correlates with the degree to which motor function is affected: The earlier the age of onset, the greater the impact on motor function. Children who display symptoms at birth or in infancy typically have the lowest level of functioning (type 1). SMA onset in children (types 2 and 3), teens or adults (type 4) generally correlates with increasingly higher levels of motor function.
For more, see Forms of SMA.
What causes SMA?
Chromosome 5 SMA is caused by a deficiency of a motor neuron protein called SMN, for "survival of motor neuron." This protein, as its name implies, seems to be necessary for normal motor neuron function. Its deficiency is caused by genetic flaws (mutations) on chromosome 5 in a gene called SMN1. Neighboring SMN2 genes can in part compensate for nonfunctional SMN1 genes.
Other rare forms of SMA (non-chromosome 5) are caused by mutations in genes besides SMN.
What are the symptoms of SMA?
SMA symptoms cover a broad spectrum ranging from mild to severe.
There's a great deal of variation in the age of onset and level of motor function achieved in chromosome 5-related SMA. These are roughly correlated with how much functional SMN protein is present in the motor neurons, which in turn is correlated with how many SMN2 genes a person has.
Sensory, mental and emotional functioning are entirely normal in chromosome-5 SMA.
Some forms of SMA are not linked to chromosome 5 or SMN deficiency. These forms vary greatly in severity and in the muscles most affected. While most forms, like the chromosome 5-related form, affect mostly the proximal muscles, other forms exist that affect mostly the distal muscles (those farther away from the body's center) at least in the beginning.
For more, see Signs and Symptoms.
What is the progression of SMA?
In chromosome 5-related SMA, the later the symptoms begin and the more SMN protein there is, the milder the course of the disease is likely to be. While in the past, infants with SMA typically did not survive more than two years, today most doctors now consider SMN-related SMA to be a continuum and prefer not to make rigid predictions about life expectancy or weakness based strictly on age of onset.
What is the status of research on SMA?
Research has focused on strategies to increase the body's production of SMN protein, lacking in the chromosome 5-related forms of the disease. Approaches in this and other forms of SMA include methods to help motor neurons survive in adverse circumstances.
The U.S. Food and Drug Administration on Dec. 23, 2016, approved nusinersen (brand name Spinraza) for the treatment of SMA. Spinraza is designed to treat the underlying defect in SMA, which means it potentially may be effective at slowing, stopping or perhaps reversing the symptoms of SMA. For more, see Spinraza is Approved.
12.2. Spinal Muscular Atrophy Description-NIH
National Institutes of Health-Us Library of Medicine description of SMA: Spinal muscular atrophy is a genetic disorder that affects the control of muscle movement. It is caused by a loss of specialized nerve cells, called motor neurons, in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem). The loss of motor neurons leads to weakness and wasting (atrophy) of muscles used for activities such as crawling, walking, sitting up, and controlling head movement. In severe cases of spinal muscular atrophy, the muscles used for breathing and swallowing are affected. There are many types of spinal muscular atrophydistinguished by the pattern of features, severity of muscle weakness, and age when the muscle problems begin.
Type I spinal muscular atrophy (also called Werdnig-Hoffman disease) is a severe form of the disorder that is evident at birth or within the first few months of life. Affected infants are developmentally delayed; most are unable to support their head or sit unassisted. Children with this type have breathing and swallowing problems that may lead to choking or gagging.
Type II spinal muscular atrophy is characterized by muscle weakness that develops in children between ages 6 and 12 months. Children with type II can sit without support, although they may need help getting to a seated position. Individuals with this type of spinal muscular atrophy cannot stand or walk unaided.
Type III spinal muscular atrophy (also called Kugelberg-Welander disease or juvenile type) has milder features that typically develop between early childhood and adolescence. Individuals with type III spinal muscular atrophy can stand and walk unaided, but walking and climbing stairs may become increasingly difficult. Many affected individuals will require wheelchair assistance later in life.
The signs and symptoms of type IV spinal muscular atrophy often occur after age 30. Affected individuals usually experience mild to moderate muscle weakness, tremor, twitching, or mild breathing problems. Typically, only muscles close to the center of the body (proximal muscles), such as the upper arms and legs, are affected in type IV spinal muscular atrophy.
The features of X-linked spinal muscular atrophy appear in infancy and include severe muscle weakness and difficulty breathing. Children with this type often have joint deformities (contractures) that impair movement. In severe cases, affected infants are born with broken bones. Poor muscle tone before birth may contribute to the contractures and broken bones seen in these children.
Spinal muscular atrophy, lower extremity, dominant (SMA-LED) is characterized by leg muscle weakness that is most severe in the thigh muscles (quadriceps). This weakness begins in infancy or early childhood and progresses slowly. Affected individuals often have a waddling or unsteady walk and have difficulty rising from a seated position and climbing stairs.
An adult-onset form of spinal muscular atrophy that begins in early to mid-adulthood affects the proximal muscles and is characterized by muscle cramping of the limbs and abdomen, weakness in the leg muscles, involuntary muscle contractions, tremors, and a protrusion of the abdomen thought to be related to muscle weakness. Some affected individuals experience difficulty swallowing and problems with bladder and bowel function.
13. Spinal Stenosis
13.1. Spinal Stenosis causes, diagnosis and treatment
Spinalstenosis.org treatment, tests etc
14.1. MicroTransponder Vivistim Paired VNS System
14.2. Spinal stroke
NINDS spinal cord stroke/infarction information page
14.3. Stroke Resources & Response
Contact Stroke.org to connect with the American Heart Association and American Stroke Association. Contact Us Form or by phone below:
Stroke Family Warmline:
1-888-4-STROKE or 1-888-478-7653
Monday-Friday: 8AM-5PM CST
Our mission is to be a relentless force for a world of longer, healthier lives. That single purpose drives all we do. Check out these quick links to help prevent, treat, and beat stroke:
- Most strokes are preventable and high blood pressure is the leading cause. Learn more at heart.org/hbp and High Blood Pressure and Stroke.
- Know the warning signs so you can spot a stroke FAST.
- Visit stroke.org to learn about the types of stroke, recovery and to find support groups.
- Subscribe to our Stroke Connection e-newsletter.
- A stroke can be scary and overwhelming. Check out stroke.org/hopeguide. You may also find our Stroke Discharge Checklist and Daily Home Care Guide helpful.
15.1. Syringomyelia information page and on-line support
ASAP works to educate and inform the public and health professionals on Chiari (CM), syringomyelia (SM) and related disorders. ASAP provides support in a variety of ways including helping people locate support groups in their area, organizing virtual support groups, offering networking opportunities including a message board, listserv and chat room.
Syringomyelia is an uncommon but disabling complication of SCI. Although more than half of all people with SCI develop a cyst in the spinal cord at the injury site, only about 4% develop syringomyelia, in which the cyst fills with fluid and expands.
Syringomyelia Factsheet/NINDS , The National Institute of Neurological Disorders and Stroke, National Institutes of Health, provides factual, accurate information on this disorder.
Siringomielia (en espanol)
15.2. Chiari Malformation-basic information from NINDS
Chiari Malformation-basic information from NINDS
16. Tarlov Cysts
16.1. Tarlov Cyst Information
Tarlov Cysts Information Page — Published by the National Institute of Neurological Disorders and Stroke
The Tarlov Cyst Disease Foundation is a volunteer-based, 501(c)(3) non-profit foundation dedicated to the research, improved diagnosis and development of successful treatments and outcomes for symptomatic Tarlov cysts.