A clinically isolated syndrome (CIS) is a clinical situation of an individual's first

neurological Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal ...

episode, caused by

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

demyelination A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This damage impairs the conduction of signals in the affected nerves. In turn, the reduction in conduction ability causes deficiency i ...

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the e ...

tissue. An episode may be monofocal, in which

symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

s present at a single site in the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

, or multifocal, in which multiple sites exhibit symptoms. CIS with enough paraclinical evidence can be considered as a clinical stage of

multiple sclerosis Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This d ...

(MS). It can also be retrospectively diagnosed as a kind of MS when more evidence is available. Brain

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classifi ...

s associated with a clinically isolated syndrome may be indicative of several neurological diseases, like

(MS) or

neuromyelitis optica Neuromyelitis optica spectrum disorders (NMOSD), including neuromyelitis optica (NMO), are autoimmune diseases characterized by acute inflammation of the optic nerve (optic neuritis, ON) and the spinal cord (myelitis). Episodes of ON and myelitis ...

. In order for such a

diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engin ...

, multiple sites in the central nervous system must present lesions, typically over multiple episodes, and for which no other diagnosis is likely. A clinically definitive diagnosis of MS is made once an

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...

detects lesions in the brain, consistent with those typical of MS. Other diagnostics include

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

analysis and evoked response testing. Currently it is considered that the best predictor of future development of clinical multiple sclerosis is the number of T2 lesions visualized by magnetic resonance imaging during the CIS and their size. It is normal to evaluate diagnostic criteria against the "time to conversion to definite". In 2001, the International Panel on the Diagnosis of multiple sclerosis issued the

McDonald criteria The McDonald criteria are diagnostic criteria for multiple sclerosis (MS). These criteria are named after neurologist W. Ian McDonald who directed an international panel in association with the National Multiple Sclerosis Society (NMSS) of America ...

, a revision of the previous diagnostic procedures to detect MS, known as the

Poser criteria Poser criteria are diagnostic criteria for multiple sclerosis (MS). They replaced the older Schumacher criteria, and now they are considered obsolete as McDonald criteria have superseded them. Nevertheless, some of the concepts introduced have rem ...

. "While maintaining the basic requirements of dissemination in time and space, the McDonald criteria provided specific guidelines for using findings on MRI and cerebrospinal fluid analysis to provide evidence of the second attack in those individuals who have had a single demyelinating episode and thereby confirm the diagnosis more quickly." Further revisions were issued in 2005.

2013 revision

The 1996 definition of the clinical courses of MS (phenotypes) was updated on 2013 by an international panel (International Advisory Committee on Clinical Trials). While the main classification in 1996 was the recovery from the attacks (this clinical feature separates RR from progressive), in the updated revision the main classification is the activity. MS courses in the new revision are divided into active and non-active, and CIS, when is active on MRI, becomes a kind of RRMS (this, of course, must be retrospectively diagnosed after the CDMS conversion) Some reviews describe CIS as "the

prodromal In medicine, a prodrome is an early sign or symptom (or set of signs and symptoms) that often indicates the onset of a disease before more diagnostically specific signs and symptoms develop. It is derived from the Greek word ''prodromos'', meaning ...

stage of MS".

CIS and conversion to MS

Before the 2010

, when it was not possible to prove dissemination of the lesions in space and time, the condition was called CIS and was considered outside the MS spectrum. As soon as dissemination was clear (a second lesion development) the situation was called "Conversion to MS". The 2010 revision of the McDonald criteria allows the diagnosis of MS with only one proved lesion (CIS). Therefore, the 2013 revision of the phenotypes for the disease course, consistently, included CIS as one of the clinical phenotypes of MS. Therefore the former expression "conversion from CIS to MS", which is still in use, should be redefined consistently with the former changes, since CIS now is inside MS.

References

External links

Diagnosing MS in Clinically Isolated Syndrome—The Role of MRI
{{Multiple sclerosis Neurological disorders Multiple sclerosis Syndromes affecting the nervous system