Multiple Sclerosis

A 32 year old female presents to the neurology clinic with a history of intermittent neurological symptoms over the past 18 months. She reports episodes of numbness, tingling, and mild weakness in her left leg that typically last about a week and resolve spontaneously. She notes that her symptoms worsen with heat exposure and after physical exertion. Over the past few months, she has also developed blurry vision in her right eye associated with pain on eye movement, along with urinary urgency and occasional incontinence. On examination, her vital signs are normal. Neurologic examination reveals mild weakness in the left leg with a motor strength of 4 out of 5, decreased sensation to light touch and vibration in the same limb, and hyperreflexia with an extensor plantar response on the left side. Cranial nerve examination shows decreased visual acuity in the right eye with a relative afferent pupillary defect, while fundoscopic examination is normal. Magnetic resonance imaging of the brain and spinal cord demonstrates multiple T2 and FLAIR hyperintense lesions in the periventricular regions. Cerebrospinal fluid analysis reveals oligoclonal IgG bands, and visual evoked potentials show delayed conduction in the right eye. What is the most likely diagnosis?

Diagnosis is Relapsing remitting multiple sclerosis.

1. Definition

Multiple sclerosis is a chronic immune mediated demyelinating disease of the central nervous system, characterized by inflammation, demyelination, gliosis, and neuroaxonal injury, with dissemination in time and space.

2. Types

1. Relapsing remitting multiple sclerosis, most common
2. Secondary progressive multiple sclerosis
3. Primary progressive multiple sclerosis

Additional categories:
4. Clinically isolated syndrome
5. Radiologically isolated syndrome

3. Etiology and Risk Factors

1. Exact cause is unknown
2. Immune dysregulation involving T cells, B cells, and macrophages
3. Environmental factors:
1. Higher latitude
2. Vitamin D deficiency
3. Epstein Barr virus infection
4. Smoking
4. Genetic association with HLA-DRB1*1501

4. Pathophysiology

1. Immune mediated destruction of myelin and oligodendrocytes
2. Formation of demyelinating plaques in:
1. Periventricular regions
2. Juxtacortical or cortical regions
3. Infratentorial regions
4. Spinal cord
3. Lesions often form around small veins
4. Active lesions show gadolinium enhancement
5. Chronic disease leads to axonal loss and gliosis

5. Clinical Features

1. Sensory symptoms such as paresthesia and vibration loss
2. Motor weakness, spasticity, hyperreflexia
3. Optic neuritis
4. Brainstem and cerebellar signs such as diplopia, ataxia, and vertigo
5. Bladder dysfunction, especially urgency and incontinence
6. Fatigue
7. Cognitive and mood disturbances

Characteristic signs:

1. Uhthoff phenomenon, worsening with heat
2. Lhermitte sign, electric shock sensation on neck flexion

6. Optic Neuritis

1. Subacute monocular vision loss
2. Pain with eye movement
3. Relative afferent pupillary defect
4. Color vision impairment
5. Fundoscopy may be normal in acute retrobulbar optic neuritis

7. Diagnosis

Diagnosis is based on clinical findings supported by MRI, CSF, and evoked potentials, with exclusion of alternative diagnoses.

7.1 MRI

1. T2 hyperintense lesions in:
1. Periventricular
2. Juxtacortical or cortical
3. Infratentorial
4. Spinal cord
2. Lesions may appear as Dawson fingers
3. Active lesions show gadolinium enhancement
4. Spinal cord lesions are typically short segment

7.2 CSF

1. Oligoclonal IgG bands
2. Increased IgG index

7.3 Evoked Potentials

1. Delayed conduction, especially visual evoked potentials

7.4 Additional Evaluation

1. Vitamin B12, TSH, ESR, ANA
2. AQP4-IgG and MOG-IgG when atypical features are present

8. Disease Course

8.1 Relapsing Remitting MS

1. Most common type
2. Episodes develop over days to weeks
3. Last more than 24 hours
4. Partial or complete recovery

8.2 Secondary Progressive MS

1. Gradual worsening after relapsing phase

8.3 Primary Progressive MS

1. Progressive disability from onset

9. Management

9.1 Acute Relapse

1. IV methylprednisolone 500 to 1000 mg daily for 3 to 7 days
2. Plasma exchange if steroid refractory

9.2 Disease Modifying Therapy

1. Interferon beta
2. Glatiramer acetate
3. Dimethyl fumarate
4. Fingolimod
5. Natalizumab
6. Ocrelizumab, especially important in progressive disease
7. Mitoxantrone, limited use due to toxicity

9.3 Symptomatic Treatment

1. Baclofen for spasticity
2. Gabapentin for neuropathic pain
3. Oxybutynin for bladder dysfunction
4. Modafinil for fatigue

9.4 Supportive Care

1. Exercise and rehabilitation
2. Avoid heat exposure
3. Smoking cessation
4. Vitamin D supplementation

10. Key Clinical Insight

Young female with relapsing neurologic deficits involving different CNS regions, optic neuritis, Uhthoff phenomenon, and characteristic MRI findings strongly suggests multiple sclerosis

11. Exam Level Pearls

1. Dissemination in time and space is required for diagnosis
2. Periventricular plaques and Dawson fingers are classic MRI findings
3. Optic neuritis with RAPD is a key presentation
4. Uhthoff phenomenon is characteristic of MS
5. Oligoclonal bands support diagnosis and may satisfy dissemination in time