Headaches & Neuropathies: Must-Know Concepts for AMC

Headaches and neuropathies are common clinical presentations that every medical professional must understand, especially those preparing for the Australian Medical Council (AMC) exams. A thorough grasp of their pathophysiology, diagnosis, and management is crucial for success in both theoretical and practical assessments. This article explores the essential concepts of headaches and neuropathies, including their classification, underlying mechanisms, diagnostic approach, and treatment strategies.

Understanding Headaches

Headaches are a prevalent neurological complaint with various etiologies ranging from benign primary headaches to life-threatening secondary causes. They are broadly classified into primary and secondary headaches.

Primary Headaches

Primary headaches occur without an underlying structural cause and include:

1. Migraine:
   • Episodic, unilateral headache with pulsating quality
   • Associated with nausea, vomiting, photophobia, and phonophobia
   • May present with aura (neurological symptoms preceding headache)
   • Triggers: Stress, hormonal changes, certain foods, sleep disturbances
   • Treatment: NSAIDs, triptans, prophylactic medications (beta-blockers, anticonvulsants, CGRP inhibitors)
2. Tension-Type Headache (TTH):
   • Bilateral, pressing/tightening sensation (“band-like”)
   • Not aggravated by physical activity, lacks nausea and vomiting
   • Commonly linked to stress and muscle tension
   • Treatment: NSAIDs, stress management, physical therapy
3. Cluster Headache:
   • Excruciating, unilateral pain around the eye
   • Associated with lacrimation, nasal congestion, ptosis, miosis
   • Occurs in clusters (multiple episodes per day over weeks to months)
   • Treatment: Oxygen therapy, triptans, preventive therapy (verapamil, lithium)

Secondary Headaches

Secondary headaches arise due to underlying medical conditions and require urgent evaluation. Important causes include:

1. Subarachnoid Hemorrhage (SAH):
   • “Thunderclap” headache, sudden and severe
   • Often due to ruptured cerebral aneurysm
   • Diagnosed with CT scan and lumbar puncture (xanthochromia)
   • Emergency management required
2. Giant Cell Arteritis (Temporal Arteritis):
   • Common in individuals >50 years old
   • Unilateral temporal headache, scalp tenderness, jaw claudication
   • Associated with vision loss
   • Diagnosed via temporal artery biopsy, treated with high-dose steroids
3. Increased Intracranial Pressure (ICP):
   • Worsens with lying down or early morning
   • Associated with nausea, vomiting, and papilledema
   • Causes include brain tumors, idiopathic intracranial hypertension (pseudotumor cerebri)

Neuropathies: Overview and Classification

Neuropathies involve dysfunction of peripheral nerves, leading to sensory, motor, or autonomic impairments. They are categorized into:

1. Mononeuropathy: Affects a single nerve due to trauma, compression, or vascular compromise (e.g., carpal tunnel syndrome, Bell’s palsy)
2. Polyneuropathy: Involves multiple nerves, often symmetrical (e.g., diabetic neuropathy, Guillain-Barré syndrome)
3. Autonomic Neuropathy: Affects autonomic functions like blood pressure, digestion, and sweating (e.g., diabetic autonomic neuropathy)

Common Neuropathies

1. Diabetic Neuropathy:
   • Most common cause of peripheral neuropathy
   • Symptoms: Numbness, burning pain, foot ulcers
   • Management: Blood sugar control, gabapentin, pregabalin, lifestyle modifications
2. Guillain-Barré Syndrome (GBS):
   • Acute inflammatory demyelinating polyneuropathy
   • Ascending weakness, areflexia, autonomic dysfunction
   • Often post-infectious (Campylobacter jejuni, viral illnesses)
   • Diagnosed via lumbar puncture (elevated protein, normal WBC), treated with IVIG/plasmapheresis
3. Carpal Tunnel Syndrome:
   • Median nerve compression at the wrist
   • Symptoms: Numbness, tingling in thumb, index, and middle fingers
   • Diagnosed with Tinel’s and Phalen’s tests
   • Management: Wrist splints, corticosteroid injections, surgery if severe
4. Bell’s Palsy:
   • Idiopathic facial nerve (CN VII) paralysis
   • Sudden onset of unilateral facial weakness
   • May be associated with viral infections (HSV, VZV)
   • Treatment: Steroids, antivirals in severe cases

Diagnostic Approach

Evaluating headaches and neuropathies requires a systematic approach:

1. History Taking: Onset, duration, quality, associated symptoms, triggers, red flags (e.g., sudden onset, fever, focal deficits)
2. Neurological Examination: Cranial nerves, motor and sensory assessment, reflexes, gait analysis
3. Investigations:
   • Imaging: CT/MRI for secondary headaches
   • Electromyography (EMG) and nerve conduction studies (NCS) for neuropathies
   • Blood tests: ESR (temporal arteritis), glucose (diabetes), vitamin B12 (deficiency neuropathy)

Management Strategies

Management depends on the underlying cause and severity:

1. Pharmacological Treatment:
   • NSAIDs, triptans for migraines
   • Antiepileptics (gabapentin, pregabalin) for neuropathic pain
   • Corticosteroids for inflammatory conditions
   • IVIG/plasmapheresis for autoimmune neuropathies
2. Lifestyle Modifications:
   • Avoiding headache triggers (e.g., caffeine, alcohol, sleep deprivation)
   • Blood sugar control for diabetic neuropathy
   • Physical therapy and ergonomic interventions for nerve compression syndromes
3. Surgical Interventions:
   • Carpal tunnel release surgery for severe cases
   • Nerve decompression for certain entrapment neuropathies

Conclusion

Understanding headaches and neuropathies is essential for medical practitioners preparing for the AMC exam. A systematic approach to diagnosis and management ensures optimal patient care. Recognizing red flags, identifying primary versus secondary headaches, and distinguishing different neuropathies are key components of clinical decision-making. By mastering these concepts, candidates can enhance their diagnostic acumen and improve their chances of success in the AMC exam. Read more blog…