Idiopathic inflammatory demyelinating diseases
Encyclopedia
Idiopathic inflammatory demyelinating diseases (IIDDs), sometimes known as borderline forms of multiple sclerosis, is a collection of multiple sclerosis
variants, sometimes considered different diseases, but considered by others to form a spectrum differing only in terms of chronicity, severity, and clinical course.
Some others include in the list also other conditions associated with the presence of the scleroses
As MS is an active field for research, the list is not closed or definitive. For example, some diseases like Susac's syndrome
(MS has an important vascular component), Myalgic encephalomyelitis (aka Chronic fatigue syndrome
) or autoimmune variants of peripheral neuropathies
like Guillain-Barré syndrome
or Progressive inflammatory neuropathy
could be included assuming the autoimmune model.
Cases of MS before the CIS are sometimes found during other neurological inspections and are referred to as subclinical MS. Preclinical MS refers to cases after the CIS but before the confirming second attack. After the second confirming attack the situation is referred to as CDMS (clinically defined multiple sclerosis).
proposal, which is the currently considered as the gold standard
for MS diagnosis. These authors state that "MS is a clinical entity and therefore should be diagnosized with clinical and paraclinical criteria" . Currently the McDonald criteria
are considered a clinical definition of MS.
Some other authors consider MS as a pathological entity instead, and propose a pathological definition. According to Hans Lassmann, the pathological definition should be preferred because clinical definitions have problems with differential diagnosis. Of course, using a pathological definition would not prevent performing clinical diagnosis, but would require to calibrate any diagnosis criteria against it.
McDonald et al. do not agree with this, and they remark the clinical character of MS. They state that "Whereas it might be said that the only proved diagnosis of MS can be made upon autopsy, or occasionally upon biopsy, where lesions typical of MS can be directly detected through standard histopathological techniques, MS is essentially a clinical problem and can be diagnosed using clinical and paraclinical criteria""
At this moment, both definitions are currently used by each of their supporters and the relationship among them is not well documented.
does not give any explicit definition with ICD-10
MS entry http://apps.who.int/classifications/apps/icd/icd10online/?gg35.htm+g35. In ICD-9 it used to say "chronic disease characterized by presence of numerous areas of demyelination in the central nervous system with symptoms such as weakness, incoordination, paresthesis, and speech disturbances"http://www.icd9data.com/2009/Volume1/320-389/340-349/340/default.htm.
The Unified Medical Language System
also gives very loose definitions of MS http://www.diseasesdatabase.com/umlsdef.asp?glngUserChoice=8412. The Medline medical dictionary defines it as "a demyelinating disease marked by patches of hardened tissue in the brain or the spinal cord and associated especially with partial or complete paralysis and jerking muscle tremor" http://www2.merriam-webster.com/cgi-bin/mwmednlm?book=Medical&va=multiple%20sclerosis. It uses the anatomical hallmark of the lesions, but also imposes the existence of clinical problems (paralysis and jerking muscle tremor)
Assuming a definition as weak as the previous ones, several diseases could be included inside the MS-spectrum. Other authors use a definition for MS based in its clinical
course http://msj.sagepub.com/cgi/content/short/14/9/1157. Clinical definitions refer to the lesions and their location, but not to the nature of the lesions and this kind of definitions are potentially heterogeneous. As with any definition, patients have to be considered non-affected until the definition conditions are satisfied.
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
variants, sometimes considered different diseases, but considered by others to form a spectrum differing only in terms of chronicity, severity, and clinical course.
Diseases included in this category
The list of these diseases depends of the author, but usually are included:- Standard multiple sclerosisMultiple sclerosisMultiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
, the most known and extended variant. - Optic-spinal MS, or Opticospinal, variant which often include visual symptoms and have a more severe course than typical MS. Though multiple scars (scleroses) are present in CNS, and sometimes Poser criteriaPoser criteriaPoser criteria are diagnostic criteria for multiple sclerosis . They replaced the older Schumacker criteria, and now they are considered obsolete as McDonald criteria have superseded them...
classifies it as clinically definite multiple sclerosis, currently is considered outside the scope of Multiple Sclerosis and inside the scope of Devic's diseaseDevic's diseaseNeuromyelitis optica , also known as Devic's disease or Devic's syndrome, is an autoimmune, inflammatory disorder in which a person's own immune system attacks the optic nerves and spinal cord. This produces an inflammation of the optic nerve and the spinal cord...
, though is not sure if this applies to all cases. - Devic's diseaseDevic's diseaseNeuromyelitis optica , also known as Devic's disease or Devic's syndrome, is an autoimmune, inflammatory disorder in which a person's own immune system attacks the optic nerves and spinal cord. This produces an inflammation of the optic nerve and the spinal cord...
, currently considered a separate disease - Acute disseminated encephalomyelitisAcute disseminated encephalomyelitisAcute disseminated encephalomyelitis is an immune mediated disease of the brain. It usually occurs following a viral infection but may appear following vaccination, bacterial or parasitic infection, or even appear spontaneously. As it involves autoimmune demyelination, it is similar to multiple...
or ADEM, a closely related disorder in which a known virus or vaccine triggers autoimmunity against myelin. - Acute hemorrhagic leukoencephalitis, possibly a variant of Acute disseminated encephalomyelitis
- Balo concentric sclerosisBalo concentric sclerosisBalo concentric sclerosis is one of the borderline forms of multiple sclerosis.Balo concentric sclerosis is a demyelinating disease similar to standard multiple sclerosis, but with the particularity that the demyelinated tissues form concentric layers...
, an unusual presentation of plaques forming concentrenic circles, which can sometimes get better spontaneously. - Schilder diseaseDiffuse myelinoclastic sclerosisDiffuse myelinoclastic sclerosis, sometimes referred to as "Schilder's disease", is a very infrequent neurodegenerative disease that presents clinically as pseudotumoural demyelinating lesions, that make its diagnosis difficult...
or diffuse myelinoclastic sclerosis: is a rare disease that presents clinically as a pseudotumoural demyelinating lesion; and is more common in children. - Marburg multiple sclerosisMarburg multiple sclerosisMarburg multiple sclerosis, also known as fulminant multiple sclerosis, is considered one of the multiple sclerosis borderline diseases, which is a collection of diseases classified by some as MS variants and by others as different diseases. Other diseases in this group are Neuromyelitis optica ,...
, an aggressive form, also known as malignant, fulminant or acute MS.
- Tumefactive Multiple sclerosisTumefactive multiple sclerosisTumefactive multiple sclerosis is a condition in which the central nervous system of a person has multiple demyelinating lesions with atypical characteristics for those of standard multiple sclerosis, including a size greater than 2 cm, presence of a mass effect, edema, or ring...
: lesions whose size is more than 2 cm, with mass effect, oedema and/or ring enhancement
- Venous multiple sclerosis: A relationship has been proposed between MS and Chronic cerebrospinal venous insufficiencyChronic cerebrospinal venous insufficiencyChronic cerebrospinal venous insufficiency is a term developed by Italian researcher Paolo Zamboni in 2008 to describe compromised flow of blood in the veins draining the central nervous system...
. The hypothetical MS variant produced by CCSVI is called Venous Multiple Sclerosis. If this hypothesis is confirmed, this variant would account for most of MS cases.
Some others include in the list also other conditions associated with the presence of the scleroses
- Optic neuritisOptic neuritisOptic neuritis is the inflammation of the optic nerve that may cause a complete or partial loss of vision.-Causes:The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the...
(monophasic and recurrent) - Transverse myelitisTransverse myelitisTransverse myelitis is a neurological disorder caused by an inflammatory process of the spinal cord, and can cause axonal demyelination. The name is derived from Greek referring to the "spinal cord", and the suffix -itis, which denotes inflammation...
(monophasic and recurrent)
As MS is an active field for research, the list is not closed or definitive. For example, some diseases like Susac's syndrome
Susac's syndrome
Susac's syndrome is a microangiopathy characterized by encephalopathy, branch retinal artery occlusions and hearing loss. It is caused by the immune system attacking healthy tissue, and can lead to mental disorders....
(MS has an important vascular component), Myalgic encephalomyelitis (aka Chronic fatigue syndrome
Chronic fatigue syndrome
Chronic fatigue syndrome is the most common name used to designate a significantly debilitating medical disorder or group of disorders generally defined by persistent fatigue accompanied by other specific symptoms for a minimum of six months, not due to ongoing exertion, not substantially...
) or autoimmune variants of peripheral neuropathies
Peripheral neuropathy
Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....
like Guillain-Barré syndrome
Guillain-Barré syndrome
Guillain–Barré syndrome , sometimes called Landry's paralysis, is an acute inflammatory demyelinating polyneuropathy , a disorder affecting the peripheral nervous system. Ascending paralysis, weakness beginning in the feet and hands and migrating towards the trunk, is the most typical symptom...
or Progressive inflammatory neuropathy
Progressive inflammatory neuropathy
Progressive inflammatory neuropathy is a disease that was identified in a report, released on January 31, 2008, by the Centers for Disease Control and Prevention. The first known outbreak of this neuropathy was in southeastern Minnesota in the United States. The disease was reported among pig...
could be included assuming the autoimmune model.
Clinical courses inside standard MS
Also inside standard MS different clinical courses can be separated.Progressive variants
Some authors also think that primary progressive multiple sclerosis should be considered a different entity from standard MS. Others maintain the opposite. In any case, the lesions in PPMS can be diffused instead of the normal focal ones. Finally, also a dual classification of these diseases has been proposed, according to the shape of edges of the scars, in MS-like and ADEM-likeSubclinical, preclinical, CIS and CDMS
The first manifestation of MS is the so called Clinically isolated syndrome, or CIS, which is the first isolated attack. The current diagnosis criteria for MS does not allow doctors to give an MS diagnosis until a second attack takes place. Therefore the concept of "clinical MS", for a MS that can be diagnosed has been developed. Until MS diagnosis has been established, nobody can tell whether the disease dealing with is MS.Cases of MS before the CIS are sometimes found during other neurological inspections and are referred to as subclinical MS. Preclinical MS refers to cases after the CIS but before the confirming second attack. After the second confirming attack the situation is referred to as CDMS (clinically defined multiple sclerosis).
Aggressive multiple sclerosis
Relapsing-Remitting MS is considered aggressive when the frequency of exacerbations is not less than 3 during 2 years. Special treatment is often considered for this subtype.Pediatric and pubertal MS
MS cases are rare before puberty, but they can happen. Whether they constitute a separate disease is still an open subject. Anyway, even this pubertal MS could be more than one disease, because early-onset and late-onset have different demyelination patternsClinical vs. pathological definitions
Probably the most implicitly used definition can be found into the McDonald criteriaMcDonald criteria
The McDonald criteria are diagnostic criteria for multiple sclerosis . These criteria are named after neurologist W. Ian McDonald. In April 2001 an international panel in association with the National Multiple Sclerosis Society of America recommended revised diagnostic criteria for MS...
proposal, which is the currently considered as the gold standard
Gold standard (test)
In medicine and statistics, gold standard test refers to a diagnostic test or benchmark that is the best available under reasonable conditions. It does not have to be necessarily the best possible test for the condition in absolute terms...
for MS diagnosis. These authors state that "MS is a clinical entity and therefore should be diagnosized with clinical and paraclinical criteria" . Currently the McDonald criteria
McDonald criteria
The McDonald criteria are diagnostic criteria for multiple sclerosis . These criteria are named after neurologist W. Ian McDonald. In April 2001 an international panel in association with the National Multiple Sclerosis Society of America recommended revised diagnostic criteria for MS...
are considered a clinical definition of MS.
Some other authors consider MS as a pathological entity instead, and propose a pathological definition. According to Hans Lassmann, the pathological definition should be preferred because clinical definitions have problems with differential diagnosis. Of course, using a pathological definition would not prevent performing clinical diagnosis, but would require to calibrate any diagnosis criteria against it.
McDonald et al. do not agree with this, and they remark the clinical character of MS. They state that "Whereas it might be said that the only proved diagnosis of MS can be made upon autopsy, or occasionally upon biopsy, where lesions typical of MS can be directly detected through standard histopathological techniques, MS is essentially a clinical problem and can be diagnosed using clinical and paraclinical criteria""
At this moment, both definitions are currently used by each of their supporters and the relationship among them is not well documented.
Current definitions
The list of diseases included in the MS-spectrum is not closed because no formal definition of MS is normally given. For example, the World Health OrganizationWorld Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
does not give any explicit definition with ICD-10
ICD-10
The International Statistical Classification of Diseases and Related Health Problems, 10th Revision is a medical classification list for the coding of diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases, as maintained by the...
MS entry http://apps.who.int/classifications/apps/icd/icd10online/?gg35.htm+g35. In ICD-9 it used to say "chronic disease characterized by presence of numerous areas of demyelination in the central nervous system with symptoms such as weakness, incoordination, paresthesis, and speech disturbances"http://www.icd9data.com/2009/Volume1/320-389/340-349/340/default.htm.
The Unified Medical Language System
Unified Medical Language System
The Unified Medical Language System is a compendium of many controlled vocabularies in the biomedical sciences . It provides a mapping structure among these vocabularies and thus allows one to translate among the various terminology systems; it may also be viewed as a comprehensive thesaurus and...
also gives very loose definitions of MS http://www.diseasesdatabase.com/umlsdef.asp?glngUserChoice=8412. The Medline medical dictionary defines it as "a demyelinating disease marked by patches of hardened tissue in the brain or the spinal cord and associated especially with partial or complete paralysis and jerking muscle tremor" http://www2.merriam-webster.com/cgi-bin/mwmednlm?book=Medical&va=multiple%20sclerosis. It uses the anatomical hallmark of the lesions, but also imposes the existence of clinical problems (paralysis and jerking muscle tremor)
Assuming a definition as weak as the previous ones, several diseases could be included inside the MS-spectrum. Other authors use a definition for MS based in its clinical
Illness
Illness is a state of poor health. Illness is sometimes considered another word for disease. Others maintain that fine distinctions exist...
course http://msj.sagepub.com/cgi/content/short/14/9/1157. Clinical definitions refer to the lesions and their location, but not to the nature of the lesions and this kind of definitions are potentially heterogeneous. As with any definition, patients have to be considered non-affected until the definition conditions are satisfied.