CLASSIFICATION AND PATHOPHYSIOLOGY OF

HEADACHE

Classification

Headaches

Primary Secondary

International Classification of Headache Disorders (ICHD)

Primary Headache A headache that is not caused by another

underlying disease,trauma or medical condition.

Accounts for about ninety percent of all

headaches.

secondary headache Caused by exogenous disorders

PRIMARY HEADACHE

TENSION TYPE HEADACHE MIGRAINE CLUSTER HEADACHE ATYPICAL FACIAL PAIN TRIGEMINAL NEURALGIA BENIGN PAROXYSMAL

BENIGN PAROXYSMAL HEADACHES

Ice pick Ice cream Exertional Cough Chronic paroxysmal hemicrania SUNCT(Short-lasting unilateral

neuralgiform head ache with conjunctival injection and tearing)

secondary causes of headache

Intracerebral bleeding Raised intracranial pressure Infection Inflammatory disease Post-herpetic neuralgia Referred pain from other structures

PATHO PHYSIOLOGY Stimulation of primary nociceptors

Lesions in pain-producing pathways of PNS&CNS

Pain-producing structures

Scalp Middle meningeal artery, Dural sinuses, Falx cerebri & Proximal segments of the large pial

arteries

The ventricular ependyma, choroid plexus, pial veins, and much of the brain parenchyma are not pain-producing.

Large intracranial vessels and dura mater Peripheral terminals of the trigeminal

nerve that innervate these structures Caudal portion of the trigeminal nucleus,

which extends into the dorsal horns of the upper cervical spinal cord and receives input from the first and second cervical nerve roots (the trigeminocervical complex)

Pain modulatory systems in the brain that receive input from trigeminal nociceptors

Key structures involved

Nerves involved

Trigeminal nerve First 3 cervical nerves Fascial nerve Glossopharyngeal and vagus nerve

Mechanisms

Distension,traction or dilatation of i/c or e/c arteries.

Traction or displacement of large intracranial veins or their envelope.

Meningial irritation & raised ICT.

Compression ,traction or inflammation of cranial or spinal nerves.

Spasm ,inflammation & trauma to cranial & cervical muscles.

Disturbance of intracerebral serotonic projection/activtn of brain stem structures.

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