If the brain does not have pain receptors, what causes the pain?
- meninges - inflammation due to meningitis.
- blood vessels - stretching/traction or distension of arteries.
- skull - sinusitis or dental problems
- muscles - the head and neck (e.g. increased muscle tension d/t TMJ)
Which nerve transmits most pain signals in the head and where does it synapse?
The trigeminal nerve.
Synapse at the brainstem.
Pain signals from the back of the head and the posterior fossa (base) of the skull are transmitted by the…
First three cervical spinal nerves.
Synapse at the brainstem.
Describe the role of second and third order neurons.
2nd order neurons = project to the thalamus then…
3rd order neurons = to the somatosensory cortex
Define primary and secondary headaches.
Primary = not caused by another disorder. Chronic and recurring.:
- migraine
- tension-type headache
- cluster-type headache
- other
Secondary = caused by another disorder so headache is a symptom:
- trauma/injury
- vascular disorder
- substance use/withdrawal etc.
What are temporomandibular disorders (TMD)?
- Caused by teeth grinding, trauma, disc displacement, degeneration (arthritis)
- headache increases with jaw movement (chewing, grinding, clenching)
- joint inflammation spreads to affect nearby muscles and fascia
Describe the pathopysiology of secondary headache.
- irritation, ischemia or stretching of pain-sensitive structures around the brain (meninges and vessels)
- or pain-sensitive structures around the head (muscle, bone, peripheral nerve, join, sinus)
What could a sudden onset (thunderclap - max intensity <1 min) headache signal?
Subarachnoid hemorrhage.
What could a new onset headache in >50 year old signal?
Brain tumor
What could focal neurological deficits lasting >1 hour signal?
CVA
What could new headache with stiff neck, fever, or rash indicate?
meningitis
What could headache with papilledema or decreased LOS indicate?
Increased ICP
What could headache triggered by sneezing, coughing or straining indicate?
Chiari malformation (the cerebellum bulges through a normal opening in the skull where it joins the spinal canal).
Describe the characteristics of a tension headache.
- most common
- bilateral
- steady pressing, tightening, bandlike quality
- mild to moderate severity
- duration: 30 mins - several days
- photophobia OR phonophobia NOT both
Pericranial and/or nuchal muscle tenderness (detected by palpation) often accompanies what type of headache?
Tension type headaches. (TTH)
Episodic vs chronic tension type headaches headaches.
Episodic = occurs < 15 days/month
Chronic = occurs 15 or >15 days/month for >3 months
Describe the pathophysiology of tension type headaches.
- exact mechanism unknown
- attributed to activation of myofascial nociceptors (head, neck shoulders) = could be triggered by stress, poor posture, and sleep disturbances
What is the role of peripheral sensitization in tension type headaches?
Peripheral sensitization of myofascial nociceptors contributes to muscular hypersensitivity in TTH.
Neuropeptides act on nociceptors to move the membrane potential closer to threshold.
Increased excitability leads to hyperalgesia or allodynia.
Describe the characteristics of cluster headaches.
- unilateral
- severe
- pain occurs around one eye (orbital or supraorbital) and may extend back toward the ear (temporal)
- one or more autonomic symptom on the affected side: eye redness/lacrimation, eyelid edema, nasal congestion/rhinorrhea, forehead/facial sweating, miosis (pupil restriction) /ptosis (upper eyelid droops)
- sense of restlessness or agitation
- Attacks are sudden and last 15-180 min
What is involved in the acute treatment of cluster headaches?
- Triptans and 100% O2 by mask
- Verapamil is most commonly used for prevention
- a CGRP antagonist or corticosteriod can be used to decrease frequency or severity during a cluster period
Describe the ‘cluster’ component of cluster headaches.
- Occur in ‘clusters’ then disappear for months/years
- cluster periods last 7 - 365 days
- frequency during cluster period: once every other day to 8 per day
- triggers during cluster period can include alcohol, nicotine, nitro etc.
What are circadian periodicity and Circannual peridocity in cluster headaches?
Circadian periodicity = single attacks often occur at the same time of day. Most common (50%) occur at night, 2-3 hours after falling asleep (known as the alarm clock headache).
Circannual periodicity = cluster periods often occur during a certain season
Describe episodic vs chronic cluster periods.
Episodic (80-90%) = separated by pain-free remission period of 3 or > 3 months
Chronic (10-15%) = occur without remission or remission periods last < 3 months.
Who is affected by cluster headaches?
- 0.1% of the population
- typically males (3:1)
- mean onset of 30 years
