Multiple Sclerosis a diagnostic guide Derived from Handbook of Multiple Sclerosis by Jeffrey A Cohen and Alexander Rae-Grant
Introduction Defining multiple sclerosis Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) that produces demyelination and axonal/neuronal damage, resulting in characteristic multifocal lesions on magnetic resonance imaging (MRI) and a variety of neurologic manifestations. This guide will provide a broad summary of diagnosing multiple sclerosis, including clinical features and diagnostic criteria. Please refer to the Handbook of Multiple Sclerosis for further information, including treatment options. Key clinical features Typical onset is in the age range 20 40 years Female predominance approximately 2.5:1 Neurologic manifestations reflect multifocal involvement of the CNS (brain, spinal cord, optic nerves) Nonfocal manifestations (eg, cognitive impairment, mood disorders, pain, and fatigue) also significantly contribute to disability Relapsing remitting (RR) course at onset in 70 80% of patients, usually evolving into a secondary progressive phase Progressive course from onset in ~20% of patients Most patients develop disability over 10 15 years The range and severity of clinical manifestations have marked heterogeneity, both in individual patients over time and between patients Diagnosis is straightforward in typical patients, but differential diagnosis is extensive when there are atypical features Effective therapies are available and should be considered early to lessen the risk of permanent disability Treatment of symptoms and addressing psychosocial sequelae are important aspects of management Objectives for patient care It is important to make a diagnosis of MS accurately and expeditiously to relieve uncertainty and allow the institution of disease-modifying therapy. The purpose of therapy is to decrease relapses and MRI activity, with the ultimate goal of reducing the long-term risk of permanent disability. Because of the myriad of potential manifestations that interfere with function and negatively impact quality of life, symptom management is also an important aspect of management.
Epidemiology and Genetics Prevalence and risk factors The prevalence of MS is approximately 1/1000, affecting approximately 400,000 people in the USA and 2 million worldwide [1]. MS is the most common nontraumatic cause of neurologic disability in young adults. Onset typically is between the ages of 20 and 40 years and women are affected more frequently than men. Approximately 70% of monozygotic twins are discordant for MS, implying an interaction between the genetic propensity for MS and environmental factors. There is a distinct latitude gradient: MS is relatively rare in the tropics and increases in prevalence with increasing latitude in both the northern and southern hemispheres. Migration studies suggest that risk of acquiring MS is determined at/before puberty. Postulated risk factors include infectious agents, diet, environmental toxins, and sunlight [2], but none has been definitively implicated. Genetic susceptability to MS Relatives of patients with MS are at increased risk for the disease and several lines of evidence indicate that MS has a genetic component [2,3]. However, the genetic basis of MS is complex (ie, multiple genes contribute cumulatively to the risk of MS and disease behavior) and is heterogeneous (ie, the genes and alleles involved probably differ from patient to patient). Genetic studies have most consistently implicated genes encoded in the class II region of the major histocompatibility complex (MHC) on chromosome 6 [4]. 270 1 1 7 35 200 197 Monozygotic twin Child of conjugal MS pair Child Sibling First cousin Adopted siblings General population Population-based prevalence of MS (per 1000) in relatives of patients with MS [5].
Pathogenesis and Prognosis Pathogenesis Pathology The pathology of MS is characterized by multifocal lesions within the CNS, both in the white matter and gray matter, with perivenular inflammatory cell infiltrates, demyelination, axonal transection, neuronal degeneration, and gliosis [6]. A B n CSO at io cortex Ed uc CC white matter lesion cortical lesion CSO re LV Sp rin ge rh ea l th ca Pathology of MS. (A) Demyelinated lesion in periventricular white matter. (B) Demyelinated lesion in cortex. CSO, centrum semiovale; CC, corpus callosum; LV, lateral ventricle. High-power view of a white matter lesion in MS. This confocal micrograph shows demyelination (arrowheads) and axonal transection (arrow).
Pathogenesis Pathogenesis Traditional theory postulates that myelin-specific CD4 + T cells play a central role in the pathogenesis of MS (see figure below). CD4 + T cell subsets, natural killer cells, monocytes/macrophages, B cells, and humoral factors have also been implicated [7]. A large number of biopsy and autopsy specimens suggested that the mechanisms leading to tissue damage differ from patient to patient [8]. Inflammatory mechanisms predominate early in the disease, but the gradual worsening in primary progressive (PP) and secondary progressive (SP) MS is due to neurodegeneration. Lymphoid tissue B cells Dendritic cell T cells T helper cell Antigens CD8 + cells Neuron B cell Oligodendrocyte Plasma cell Antibodies CD4 + cells Cytokines Microglia Hypothetical view of immune response in acute multiple sclerosis lesion. T- and B-cell responses are primed in the peripheral lymphoid tissue by antigens. After clonal expansion, T and B cells infiltrate the CNS. Clonally expanded B cells re-encounter their specific antigen, mature to plasma cells, and release large amounts of antibodies. These antibodies bind soluble or membrane-bound antigen on expressing cells. Clonally expanded CD8+ T cells also invade the brain and could encounter their specific peptide ligand, presented by glial or neuronal cells on MHC class I molecules. The recognition of specific MHC-peptide complexes on these cells prompts direct damage to expressing cells. CD4+ T cells migrate into the CNS and encounter antigens that are presented by microglial cells on MHC class II molecules. Reactivation of these cells leads to heightened production of inflammatory cytokines that attract other immune cells, such as macrophages, which contribute to inflammation through the release of injurious immune mediators and direct phagocytic attack on the myelin sheath. Figure reproduced with permission from Hemmer et al [9] Nature. CNS
Clinical Presentation Clinical manifestations The wide range of symptoms and signs of MS reflect multifocal lesions in the CNS, including in the afferent visual pathways, cerebrum, brainstem, cerebellum, and spinal cord. Not all symptoms will be present in every patient and can vary greatly between patients. Typical clinical manifestations of MS Category Description Visual Visual loss: monocular (pre-chiasmatic) or homonymous (post-chiasmatic), double vision, oscillopsia Vestibular Vertigo, lack of balance Bulbar Dysarthria, swallowing dysfunction dysfunction Motor Weakness, spasticity, incoordination, tremor Sensation Sensory loss: any modality or distribution Positive sensory phenomena: paresthesias, dysesthesias, neuropathic pain Gait impairment Varying contributions from visual impairment, vestibular symptoms, weakness, spasticity, ataxia, imbalance, sensory loss, pain, and fatigue Urinary Urgency, frequency, hesitancy, retention, incontinence, frequent urinary symptoms tract infections Bowel symptoms Constipation, urgency, incontinence, bladder spasms Sexual Decreased libido, erectile dysfunction, anorgasmia dysfunction Cognitive Poor concentration or attention, slowed thinking, poor memory (particularly impairment short-term), impaired executive function Mood disorders Depression, anxiety, affective release Fatigue Handicap fatigue: increased effort to perform routine tasks Motor fatigue: decreased performance or endurance with sustained effort Heat intolerance: worsening symptoms with increased body temperature Systemic fatigue: persistent lassitude Pain Chronic neuropathic pain, paresthesias, dysesthesias Paroxysmal sensory symptoms (eg, neuralgic pain) Spasticity: spasms, uncomfortable increased muscle tone Proxysmal motor phenomena (eg, tonic spasms) Pain associated with acute inflammatory lesions and irritation of adjacent meninges (eg,optic neuritis, chronic photophobia following optic neuritis) Mechanical back or joint pain from immobility Compression fractures Paroxsymal phenomena Epileptic seizures Nonepileptic paroxysmal motor phenomena (eg, paroxysmal dystonia) Nonepileptic paroxysmal sensory phenomena (eg, Lhermitte s phenomena) Uthoff s phenomenon
Clinical Presentation Disease course The course of MS is categorized based on how clinical manifestations develop over time and on the severity and tempo of the disease [10]. MS begins with a RR course in 70 80% of patients. A relapse (or exacerbation or attack) is defined by the following characteristics: new, worsening, or recurrent neurologic symptoms consistent with MS, typically develops over days to weeks, lasts at least 24 48 hours, and accompanied by an objective change on the neurologic examination corresponding to the patient s symptoms [11]. Relapses are heterogeneous within and between patients in terms of neurologic manifestations, frequency, severity, and degree of recovery. The diagnosis of RR MS is confirmed when recurrent CNS inflammatory events occur (either a second relapse or new MRI lesion activity). When a patient has had only a single relapse, the initial event is called a clinically isolated syndrome (CIS). Even without treatment, most relapses recover partially or completely over weeks to months, particularly early in the disease; however, not all relapses recover completely, and early in the disease most impairment/disability accrual is the result of incomplete relapse recovery [12]. After 10 15 years, most patients with RR MS exhibit gradual worsening of disability, known as the SP phase. Approximately 15% of patients with MS demonstrate gradual worsening disability from onset, known as primary progressive (PP) MS. Other categories of MS include progressive-relapsing (~5% of patients), fulminant (~5%), and benign (~10 20% of patients). Categories of multiple sclerosis CIS One episode of inflammatory CNS demyelination RR MS Recurrent episodes of inflammatory CNS inflammation with stable clinical manifestations between episodes SP MS Gradual neurologic deterioration, with or without superimposed relapses, in a patient with prior RR MS PP MS Gradual neurologic deterioration from onset without superimposed relapses Progressiverelapsing Fulminant Benign Gradual neurologic deterioration from onset with subsequent superimposed relapses Severe MS with frequent relapses and/or rapid disability progression MS that remains mild over a prolonged course with rare relapses and minimal disability accumulation
Clinical presentation RR SP Neurologic Impairment CIS 0 4 8 12 16 20 Time (years) Typical disease course in relapsing MS. The initial relapse is a CIS. The diagnosis of RR MS is confirmed when a second clinical/mri event occurs. In RR MS, disability accrues from incomplete recovery from relapses. Relapses vary in neurologic manifestations, frequency, severity, and degree of recovery. Most patients evolve into an SP course 10 15 years after onset, although the transition is indistinct, with decreasing relapse frequency and onset of gradual worsening between relapses. Late in the disease, there is gradual progression without relapses. 1. Marrie RA. Environmental risk factors in multiple sclerosis aetiology. Lancet Neurol. 2004;3:709-718. 2. Ebers GC. Environmental factors and multiple sclerosis. Lancet Neurol. 2008;7:268-277. 3. Dyment DA, Ebers GC, Sadovnick AD. Genetics of multiple sclerosis. Lancet Neurol. 2004;3:104-110. 4. The International Multiple Sclerosis Genetics Consortium. A high-density screen for linkage in multiple sclerosis. Am J Hum Genet. 2005;77:454-467. 5. The International Multiple Sclerosis Genetics Consortium. Risk alleles for multiple sclerosis identified by a genomewide study. N Engl J Med. 2007;357:851-862. 6. Lucchinetti CF, Parisi J, Bruck W. The pathology of multiple sclerosis. Neurol Clin. 2005;23:77-105. 7. Frohman EM, Racke MK, Raine CS. Multiple sclerosis the plaque and its pathogenesis. N Engl J Med. 2006;354:942-955. 8. Morales Y, Parisi JE, Lucchinetti CF. The pathology of multiple sclerosis: evidence for heterogeneity. Adv Neurol. 2006;98:27-45. References 9. Hemmer B, Archelos JJ, Hartung H-P. New concepts in immunopathogenesis of multiple sclerosis. Nat Rev Neurosci. 2002;3:291-301. 10. Lublin FD, Reingold SC. Defining the clinical course of multiple sclerosis: Results of an international survey. Neurology. 1996;46:907-911. 11. Polman CH, Reingold SC, Edan G, et al. Diagnostic criteria for multiple sclerosis: 2005 revisions to the McDonald Criteria. Ann Neurol. 2005;58:840-846. 12. Lublin FD, Baier M, Cutter G. Effect of relapses on development of residual deficit in multiple sclerosis. Neurology. 2003;61:1528-1532. 13. Traboulsee A, et al. Revised recommendations of the CMSC task force for standardized MRI protocol and clinical guidelines for MS. CMSC website. Accessed May 19, 2015. 14. Polman CH, Reingold SC, Banwell B, et al. Diagnostic criteria for multiple sclerosis: 2010 revisions to the McDonald Criteria. Ann Neurol. 2011;69:292-302. 15. Miller DH, Weinshenker BG, Filippi M, et al. Differential diagnosis of suspected multiple sclerosis: a consensus approach. Mult Scler. 2008;14:1157-1174 Source material: Cohen JA, Rae-Grant A. Handbook of Multiple Sclerosis. London: Springer Healthcare; 2012. Handbook ISBN: 978-1-908517-49-4 Diagnostic guide ISBN: 978-1-910315-29-3
Diagnosis Guidance for diagnostic investigation Making an accurate diagnosis, as early as possible, will allow for the timely use of disease-modifying therapy, while also removing uncertainty and allowing for informed career and family planning. However, with the push to make the diagnosis early, there is a possible increased risk of misdiagnosis. History When a diagnosis of MS is being considered, the patient history should focus on: - the range of neurologic symptoms; - the time course over which the neurologic symptoms developed/improved; - the effects of therapeutic interventions; and - manifestations that suggest the presence of other conditions/ms mimics. Physical examination Physical examination focuses on assessing the presence of neurologic manifestations to determine whether they indicate multifocal CNS involvement. Cerebrospinal fluid analysis Cerebrospinal fluid (CSF) examination is an important ancillary test for diagnosing MS that can provide additional support when clinical features and MRI are insufficient to make a definitive diagnosis. Typical CSF findings in MS Opening pressure Normal Glucose Normal Protein Normal in 2 out of 3 patients with MS, rarely >100 mg/dl Erythrocytes Leukocytes Microbiologic studies Cytology Intrathecal antibody production Measures of tissue injury Absent Absent in 2 out of 3 patients with MS, usually <50/mm 3, rarely >100 /mm 3 ; predominantly mononuclear cells Negative Negative Increased total immunoglobulin (Ig)G, increased IgG index and synthesis rate, (+) oligoclonal bands, or increased free kappa light chains Increased myelin basic protein
Diagnosis Magnetic resonance imaging MRI is utilized for the diagnosis of MS by demonstrating the presence of: - lesions typical of MS; - asymptomatic lesions indicating whether the criteria of anatomic dissemination and development of lesions over time are satisfied; and - lesions with imaging features atypical of MS (possible alternative diagnosis). In patients with known MS, MRI is also used to rule out development of a superimposed disease process. Revised consensus guidelines for MRI in MS have recently been published [13]. A B C D E F MRI lesions characteristic of MS. (A) Axial FLAIR image showing T2 lesions in periventricular white matter, centrum semiovale, subcortical white matter; (B) axial T1-weighted image showing rim and diffuse gadoliniumenhancing foci; (C) sagittal FLAIR image showing lesions in corpus callosum; (D) axial T2-weighted image showing right middle cerebellar peduncle lesion; (E) axial T2-weighted image showing a left midbrain peduncle lesion; (F) sagittal T2-weighted image of cervical spine showing multiple patchy lesions. Evoked potentials Evoked potentials are utilized to demonstrate subclinical involvement (slowed conduction) in CNS sensory pathways when the neurologic examination and MRI are insufficient to provide objective evidence of a multifocal disease process.
Diagnosis McDonald diagnostic criteria There is no pathognomonic clinical, laboratory, imaging finding, or combination of findings to diagnose MS and, ultimately, making a diagnosis involves weighing the evidence supporting MS against factors suggesting a different condition. Specifically, one assembles data by evaluating the following: - how the CNS is affected (ie, dissemination in space [DIS]); - the disease course (ie, dissemination in time [DIT]); - inflammatory features assessed by CSF or MRI examination; and - eliminating other likely causes. This diagnostic logic for MS is delineated in the currently used McDonald Criteria, a combination of clinical, imaging, and ancillary tests [14]. McDonald criteria for diagnosing MS Clinical presentation 2 relapses; objective clinical evidence of 2 lesions or objective clinical evidence of 1 lesion with reasonable historical evidence of a prior relapse 2 relapses; objective clinical evidence of 1 lesion 1 relapse; objective clinical evidence of 2 lesions 1 relapse; objective clinical evidence of 1 lesion (CIS) Insidious neurologic progression suggestive of MS Additional data needed for diagnosis None DIS, demonstrated by MRI or a further clinical relapse DIT, demonstrated by MRI or a further clinical relapse DIS, demonstrated by MRI or a second clinical relapse, and DIT, demonstrated by MRI or a second clinical relapse 1 year of disease progression plus two out of three of the following: evidence for DIS in the brain, demonstrated by MRI ( 1 T2 lesions) evidence for DIS in the spinal cord, demonstrated by MRI ( 2 T2 lesions) positive CSF DIS can be demonstrated by 1 T2 lesion in at least two out of four of the following areas : periventricular juxtacortical DIT can be demonstrated by a new T2 and/or Gd-enhancing lesion(s) on follow-up MRI, with reference to a baseline scan, irrespective of the timing of the baseline MRI; and simultaneous presence of asymptomatic Gd-enhancing and nonenhancing lesions at any time. Reproduced with permission from Polman et al [14] Wiley. infratentorial spinal cord
Diagnosis Differential diagnosis The potential differential diagnosis of MS is extensive [15] and it is useful to make a preliminary determination of which categories the patient belongs to before undertaking extensive testing: - clinical and imaging features classic for MS: cranial MRI and screening blood tests usually are sufficient; extensive testing is not needed; - initial episode typical of an MS relapse (CIS): commonly involves optic neuritis, a cerebral syndrome, brainstem syndrome, or patrial transvere myelitis; cranial MRI (plus spine MRI) and blood tests usually suffice (similar to classic MS); - MS plus additional superimposed condition: remain vigilant for the presence or development of an additional disease process in patients with known MS, as a superimposed disorder may explain/contribute to atypical manifestations; and - compatible with the diagnosis of MS but with atypical features ( red flags ): additional testing tailored to the clinical situation is necessary to confirm MS and eliminate other possibilities, such as an MS mimic. This includes the absence of expected features, especially in long-standing disease. Differential diagnosis of MS Monophasic CNS inflammatory demyelinating syndromes (ie, CIS): optic neuritis, cerebral, brainstem, partial transverse myelitis Fulminant idiopathic CNS inflammatory syndromes: acute disseminated encephalomyelitis, Devic s neuromyelitis optica, Marburg s disease, tumefactive MS, Baló s concentric sclerosis, Schilder disease Inflammatory/immune disorders: systemic lupus erythematosus, Sjögren s syndrome, Behçet s syndrome, Wegener s granulomatosis, polyarteritis nodosa, isolated CNS vasculitis, Susac s syndrome, Sneddon s syndrome, sarcoid, celiac disease, stiff-person syndrome, treatment with tumor necrosis factor blockers Infection: Lyme disease, syphilis, human immunodeficiency virus, human T cell lymphoma virus, progressive multifocal leukoencephalopathy, Whipple s disease, herpes viruses, mycoplasma, chlamydia Vascular: small vessel ischemia, migraine, emboli, antiphospholipid antibody syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, cavernous angioma of brainstem Genetic/degenerative: mitochondrial cytopathy, hereditary spastic paraplegia, hereditary cerebellar ataxias, presenilin-i disorders, leukodystrophies, adrenomyeloneuropathy, Fabry s disease, Alexander s disease, Niemann Pick disease, glutaryl-coenzyme A dehydrogenase deficiency, Pelizaeus Merzbacher disease, Krabbe s disease, olivopontocerebellar atrophy, motor neuron disease, hereditary episodic ataxias Metabolic: thyroid disease, vitamin B 12 deficiency, nitrous oxide intoxication, copper deficiency, porphyria Neoplastic: CNS lymphoma, intravascular lymphoma, metastasis, histiocytosis, paraneoplastic Spine: vascular malformations, tumor, degenerative spine disease