So let's talk about the TACs,
the trigeminal autonomic cephalalgias,
they're less common.
We don't see them as much as
migraine and tension-type.
But when we see them, you got to
be able to diagnose this condition.
It's managed very differently
from migraine and in tension-type.
And for patients, it can really be
quite a severe cause of head pain
and require urgent intervention
to help alleviate their suffering.
How do patients describe headaches from
a trigeminal autonomic cephalalgia?
these are short lasting headaches
often on the same side
as a unilateral headache.
The various syndromes and we'll
talk about 3 or 4 TAC syndromes
differ in the attack
frequency and duration.
There's some overlap
with trigeminal neuralgia
and we'll talk about the pathophysiology
of these and learn about that.
There's activation of the
trigeminal autonomic reflex.
And this is what causes those
autonomic findings tearing
or rhinorrhea or miosis or mydriasis
and prominent autonomic findings
as a result of
and sympathetic underactivity.
And there's some evidence also
for hypothalamic activation,
which may contribute
to patient symptoms.
Interestingly, patient's symptoms are
often in a trigeminal distribution,
typically in a V1 distribution.
Though sometimes we do see V2,
V3 distribution, like trigeminal neuralgia.
What's the pathophysiology of the
trigeminal autonomic cephalalgias?
How do these work?
What causes them?
Well, there's a number of
systems that are activated
that contribute to
pain in these patients.
And the first is activation
of the pain system.
The trigeminal nerve and the
trigeminal vascular complex.
This exists in the medulla down in
the medullary region of the brainstem
and extends up into the trigeminal
nerve and nuclear regions.
This connects to
the pain neuromatrix
which is thought to generate
pain and contribute to pain.
The molecule that is
involved in activation
of the trigeminal vascular
complex is thought to be CGRP.
This is a prominent molecule
involved in the pathophysiology.
And this has been a target for some
of the triptans and other agents.
In general, this pain system is
called the pain neuromatrix system
and this contributes to pain in
these patients who present with TACs.
In addition, we see cranial
autonomic system activation
through activation at the level
of the superior salivary nucleus
that connects to the
And the molecule that's critical
in this pathway is the VIP,
and this has been a target for
oxygen that can be delivered
as an abortive agent for
patients with cluster.
In addition to the
has been implicated in the
activation of the system
and sometimes we consider blocks
into the sphenopalatine ganglion
anaesthetic blocks to manage patients who
have particularly difficult to treat pain.
And then the last is
the hypothalamic system.
And activation of the hypothalamic
system is also thought to contribute
to some of the autonomic
features that we see in the TACs.
here is melatonin.
And this has been a target
for Verapamil and lithium,
and may explain why patients
have prominent autonomic features
which we don't see with
migraine and tension-type.
So how do we approach these patients
with a trigeminal autonomic cephalalgia?
How do we make a diagnosis?
How do we know what
type of TAC it is?
Well, this algorithm helps.
All patients present with
chronic recurrent episodes.
So episodes where they have
very severe headache attacks
that often remit and they
have a headache free interval
followed by a
clustering of attacks.
Patients have prominent
So we ask about
tearing and rhinorrhea
and miosis and mydriasis,
change in the size of the pupil.
And most importantly, we want to
quantify the duration of the attacks.
Attacks may last
15 to 180 minutes,
attacks may last
2 to 30 minutes,
or attacks may be very short,
lasting 1 to 10 minutes.
Those that last a little bit longer,
we tend to categorize as cluster.
Cluster headache tends to
last 15 to 180 minutes.
The TAC that tends to last
this intermediate duration,
2 to 30 minutes is the
And those very short attacks tend
to be seen in patients with SUNCT.
headache or neuralgia form headache with
conjunctival, injection and tearing.
And so this is how we
categorize the type of TAC
that a patient may
be presenting with.