Giant Cell Arteritis (GCA)

A 55 year old female presents to the neurology clinic with a 7-day history of right-sided temporal headache. On the morning of presentation, she experienced a sudden episode of painless transient visual loss in the right eye that resolved within 15 to 20 minutes. She also reports scalp tenderness, jaw claudication, and bilateral shoulder stiffness. Over the past 6 months, she has had fatigue, unintentional weight loss, and low-grade fever. On examination, temperature is 99.9°F. Palpation reveals a tender, thickened temporal artery with reduced pulsation. Neurological examination is otherwise normal. Laboratory studies show ESR 100 mm/hr, elevated CRP, and anemia of chronic disease. Temporal artery biopsy demonstrates granulomatous inflammation with multinucleated giant cells. CT angiography shows arterial wall thickening with luminal narrowing of the carotid artery. Diagnosis? 

Diagnosis is Giant Cell Arteritis (Temporal Arteritis).

1. Definition

Giant cell arteritis is a chronic granulomatous vasculitis of large and medium-sized arteries, predominantly involving branches of the carotid artery, especially the external carotid artery such as the temporal artery, but it may also involve the aorta and its major branches. It occurs in patients older than 50 years and is strongly associated with polymyalgia rheumatica.

2. Pathogenesis

1. Immune-mediated inflammation involving T lymphocytes and macrophages
2. Activation of vascular dendritic cells
3. Release of cytokines such as IL-6 and IFN-γ
4. Leads to:
• Granuloma formation with multinucleated giant cells
• Intimal hyperplasia
• Luminal narrowing and ischemia

3. Clinical Features

3.1 Cranial Features

1. New-onset temporal headache
2. Scalp tenderness
3. Jaw claudication, highly specific
4. Visual symptoms such as amaurosis fugax, diplopia, or vision loss

3.2 Systemic Features

1. Low-grade fever
2. Fatigue
3. Weight loss

3.3 Associated Condition

1. Polymyalgia rheumatica with shoulder and hip girdle stiffness

4. Diagnostic Evaluation

4.1 Laboratory Findings

1. Elevated ESR and CRP, often markedly increased
2. Normocytic anemia
3. Thrombocytosis may be present

4.2 Imaging

1. Ultrasound showing halo sign
2. CTA or MRA showing:
• Arterial wall thickening
• Luminal narrowing
• Large vessel involvement

4.3 Temporal Artery Biopsy

1. Gold standard for diagnosis
2. Shows granulomatous inflammation with multinucleated giant cells
3. Segmental involvement (skip lesions) may cause false negatives

5. Management

5.1 Immediate Principle

1. Start glucocorticoids immediately when GCA is suspected
2. Do not delay treatment for biopsy

5.2 Glucocorticoid Therapy

1. Without visual symptoms:
• Oral prednisone 40 to 60 mg daily
2. With visual symptoms or impending vision loss:
• IV methylprednisolone 500 to 1000 mg daily for 3 days
• Followed by high-dose oral prednisone
3. Gradual taper over 12 to 18 months based on clinical response and inflammatory markers

6. Adjunctive Therapy

1. Tocilizumab for relapsing or steroid-dependent disease
2. Methotrexate as an alternative

7. Antiplatelet Therapy

1. Low-dose aspirin is often recommended to reduce risk of ischemic complications

8. Supportive Therapy

1. Calcium and vitamin D
2. Bisphosphonates

9. Complications

1. Irreversible vision loss due to anterior ischemic optic neuropathy
2. Aortic aneurysm and dissection
3. Stroke

10. Important Clinical Rule

1. Do not delay steroids for biopsy
2. Biopsy should ideally be performed within 1 week, but may remain positive up to 2 weeks after starting steroids

11. Key Clinical Insight

Age > 50 + new headache + jaw claudication = Giant cell arteritis until proven otherwise

Transient visual loss is a warning sign of impending permanent blindness

12. Exam Level Pearls

1. Jaw claudication is the most specific symptom
2. ESR is often > 100 mm/hr
3. Temporal artery biopsy is the gold standard
4. Skip lesions can cause false-negative biopsy
5. Immediate steroids prevent vision loss

Graves disease

A 38 year old female presents to her primary care physician with a 3 month history of weight loss despite good appetite, palpitations, and insomnia. She also reports anxiety and a fine tremor in her hands. Vital signs show a heart rate of 110 beats per minute and blood pressure of 140/80 mm Hg. Examination reveals exophthalmos, a diffusely enlarged non-tender thyroid, and a fine tremor. Thyroid function tests show low TSH with elevated free T3 and free T4. Serology shows positive thyroid stimulating immunoglobulin. Radioactive iodine uptake shows diffuse increased uptake. Diagnosis?

Diagnosis is Graves disease.

1. Definition

Graves disease is an autoimmune disorder caused by TSH receptor stimulating antibodies, leading to excess thyroid hormone production.

It is the most common cause of hyperthyroidism, accounting for 60 to 80 percent of cases

2. Etiology and Risk Factors

1. Autoimmune loss of immune tolerance
2. Strong genetic predisposition
3. Environmental triggers such as smoking, stress, and vitamin D deficiency

3. Pathophysiology

1. TSH receptor antibodies stimulate thyroid hormone synthesis
2. Cause diffuse thyroid hyperplasia and goiter
3. Lead to hyperthyroidism
4. Orbital fibroblast activation
5. Deposition of glycosaminoglycans
6. Results in ophthalmopathy

4. Clinical Features

4.1 Hyperthyroid Features

1. Weight loss with increased appetite
2. Tachycardia and possible atrial fibrillation
3. Heat intolerance and sweating
4. Fine tremor
5. Hyperdefecation
6. Anxiety and insomnia

4.2 Thyroid Findings

1. Diffuse goiter
2. Thyroid bruit

4.3 Extrathyroidal Features

1. Ophthalmopathy, specific but not universal
2. Exophthalmos, lid lag, periorbital edema
3. Pretibial myxedema, uncommon

5. Diagnosis

1. Low TSH with elevated T3 and T4
2. TSH receptor antibodies confirm diagnosis
3. Diffuse increased RAI uptake distinguishes from thyroiditis
4. T3 toxicosis may occur early

6. Management

1. Beta blockers such as propranolol
• Control symptoms
• High doses reduce T4 to T3 conversion
2. Antithyroid drugs
• Methimazole is first line
• Propylthiouracil in first trimester and thyroid storm
3. Radioactive iodine therapy
• Causes thyroid ablation
• May worsen ophthalmopathy
• Contraindicated in pregnancy
4. Thyroidectomy
• Indicated in large goiter or refractory disease

7. Complications

1. Thyroid storm
2. Atrial fibrillation
3. Heart failure due to high-output state
4. Osteoporosis

8. Key Clinical Insight

Diffuse goiter, exophthalmos, low TSH, elevated T3 and T4, positive TSH receptor antibodies, and diffuse RAI uptake strongly indicate Graves disease

9. Exam Level Pearls

1. Graves disease is the most common cause of hyperthyroidism
2. Diffuse RAI uptake differentiates it from thyroiditis
3. Only common hyperthyroidism with ophthalmopathy
4. Methimazole is first line except in pregnancy and thyroid storm
5. Radioactive iodine is contraindicated in pregnancy and may worsen eye disease

Supraventricular Tachycardia (SVT)

A 28 year old female presents to the emergency department with sudden onset palpitations that began 30 minutes ago while studying. She describes the sensation as her heart racing and reports lightheadedness, but denies chest pain, dyspnea, or syncope. She has had similar self-resolving episodes in the past. She drinks 2 to 3 cups of coffee daily. On examination, pulse rate is 180 beats per minute, blood pressure is 110/70 mm Hg, respiratory rate is 16 breaths per minute, temperature is 98.2°F, and oxygen saturation is 96 percent on room air. She appears anxious but alert and oriented. ECG shows a regular narrow QRS complex tachycardia with absent visible P waves. Diagnosis?

Diagnosis is Supraventricular Tachycardia (SVT), most likely AVNRT.

1. Definition

Supraventricular tachycardia is a group of tachyarrhythmias originating at or above the atrioventricular node, characterized by a narrow QRS complex (< 120 ms) and heart rate typically 150 to 220 bpm.

2. Types

1. Atrioventricular nodal reentrant tachycardia (AVNRT) most common in young adults
2. Atrioventricular reentrant tachycardia (AVRT)
3. Atrial tachycardia

3. Etiology and Triggers

1. Caffeine, alcohol, and stimulants
2. Emotional or physical stress
3. Medications such as beta agonists
4. Electrolyte abnormalities or structural heart disease

4. Pathophysiology

1. Reentry circuits involving the AV node or accessory pathways
2. Leads to rapid, regular tachycardia

5. Clinical Features

1. Sudden onset palpitations
2. Lightheadedness or dizziness
3. Anxiety
4. May include chest discomfort, dyspnea, or syncope

6. Diagnostic Evaluation

6.1 ECG Findings

1. Regular narrow complex tachycardia
2. Absent or hidden P waves
3. May show pseudo R' in V1 or pseudo S waves in inferior leads
4. Heart rate typically 150 to 220 bpm

6.2 Clinical Assessment

1. Assess for hemodynamic instability such as hypotension, altered mental status, ischemia, or shock

7. Key Diagnostic Insight

Regular narrow complex tachycardia with absent P waves strongly suggests AVNRT

8. Management

8.1 Hemodynamically Unstable

1. Immediate synchronized cardioversion

8.2 Hemodynamically Stable

1. Vagal maneuvers, preferably modified Valsalva maneuver
2. Adenosine is first-line pharmacologic therapy
3. Alternatives include beta blockers or calcium channel blockers

8.3 Important Pharmacologic Insight

1. Adenosine acts by transient AV node blockade
2. Effective only in AV node dependent tachycardias
3. Does not terminate atrial tachycardia, atrial flutter, or atrial fibrillation

8.4 Additional Considerations

1. Avoid carotid massage in patients with carotid disease
2. Caffeine may reduce adenosine effectiveness

8.5 Definitive Treatment

1. Radiofrequency catheter ablation

9. Indications for Ablation

1. Recurrent symptomatic episodes
2. Medication intolerance or failure
3. Accessory pathway mediated tachycardia

10. Complications

1. Tachycardia-induced cardiomyopathy if prolonged
2. Rare progression to hemodynamic instability

11. Key Clinical Insight

Paroxysmal episodes of rapid, regular palpitations in a young patient strongly suggest AVNRT

12. Exam Level Pearls

1. AVNRT is the most common SVT in young adults
2. Absent or hidden P waves are characteristic
3. Pseudo R' and pseudo S waves are classic ECG findings
4. Adenosine terminates AV node dependent tachycardia
5. Do not delay cardioversion in unstable patients