World Surgery Forum

What are the pain sensitive intracranial structures?

Brain itself is pain insensitive. 

The following intracranial structures are pain-sensitive:

1. Meningeal arteries
2. Proximal portions of the cerebral arteries
3. Dura at the base of the brain
4. Venous sinuses
5. Cranial nerves 5, 7, 9, and 10, and cervical nerves 1, 2, and 3

What are the mechanisms causing headaches?

• Distortion or traction of Dura, Venous Sinuses or Blood vessels: 

• Drainage of CSF in erect posture causes headache, secondary to traction on the venous sinuses when the brain sinks toward the tentorium as it loses CSF flotation
• Intracranial mass distorts the dura or the arteries at the base of the brain 
• Distortion due to raised ICP 

• Distension of a vessel

• Distension of extracranial and occasionally intracranial arteries is thought to be the cause of pain in migraine (activate the trigeminal nerve terminals in the vessel wall)

• Inflammation

• Inflammation in the subarachnoid space can result in headache. Inflammation can be caused by infection, hemorrhage, or chemical irritation
• Inflammation of vessel wall by autoimmune process. eg Giant cell arteritis

• Referral of Pain

• Lesions above the tentorium - referred pain in trigeminal nerve distribution (the forehead or behind the eye) - because the dura in this region is supplied by the trigeminal nerve
• Lesions in the posterior fossa - 
• referred pain in the ear and the back of the head - because this part of the dura is supplied by cranial nerves 9 and 10 and the upper three cervical roots
• refer pain to orbit -  termination of orbital (ophthalmic division) pain nerve fibers in the lowest part of the spinal nucleus of the trigeminal nerve, which also receive termination of the upper cervical pain afferent nerve fibers 
• referred pain to ear - Irritation of cranial nerves 7, 9, and 10 - because the ear has cutaneous supply from each of these nerves as well as cranial nerve 5.

What are the types of Headaches?

For the purpose of history taking, headaches can be divided into two types:

• Primary- no identifiable cause on examination or investigation and diagnosis is based on  recognizing a pattern, e.g.
• Migraine
• Cluster headache
• Tension-type headache
• Secondary - definite identifiable cause on examination or investigation, e.g. 
• Brain tumors
• Meningitis
• Sub-arachnoid hemorrhage 
• 90% - primary headaches, less than 10% are secondary headaches (Rasmussen 1991)

What are the headache "Red Flags"?

• Worst Headache ever
• New onset Headache
• Onset after age of 50 yrs
• Change in pattern of headache
• Worsening headache
• Sudden onset during exertion, sneezing, coughing
• Headache with postural variation
• Headache in setting of malignancy or HIV
• Headache associated with Neurological symptoms or signs
• Associated with systemic symptoms - fever, weight loss and chronic cough

What history to take in a patient presenting with Headache?

Duration

Exact duration as reported by patient

NEW onset headache or something that has been there since before and has worsened now

Onset ( sudden/ gradual )

Acute onset, severe, first and worst headache, the common possibilities are sub-arachnoid hemorrhage, vascular dissection, pituitary apoplexy

Gradual onset – migraine(mins to days), SDH, GCA(days to months)

Severity

verbal rating scale from 0 to 10

Character

Pulsatile or throbbing or hammering (Raised ICP Headaches/ Migraine)

Dull featureless pain (Tension type headache)

Boring sharp- cluster HA

Time of occurrence

Raised ICP headaches - More in morning, May waken the patient at an early hour

Frequency

Increase in frequency - red flag

Distribution

Frontal or Holocranial - Raised ICP

Band like - tension headaache

Aggravating factors

Exertion, coughing, sneezing, stooping, and straining at stool

Changes in posture (increases in supine - ↑ICP , increases in upright – low CSF pressure headache)

Relieving factors

Improvement on lying flat - low pressure headache

Associated features

Blurring of Vision - Papilloedema

Diplopia, the commonest cause of which is abducens nerve paresis

Nausea & vomiting – migraine, ↑ICP

Neck stiffness – meningeal process

Changes in consciousness

Focal neurological symptoms

References

• Ravishankar K. The art of history-taking in a headache patient. Ann Indian Acad Neurol. 2012;15(Suppl 1):S7–S14. doi:10.4103/0972-2327.99989
• Rasmussen BK, Jensen R, Schroll M, Olesen J. Epidemiology of headache in a general population – a prevalence study. J Clin Epidemiol. 1991;44:1147–57
• https://www.dartmouth.edu/~dons/part_2/chapter_18.html

12/24/2019 10:06:00 PM