User:Gth742d/SUNCT

Short-lasting Unilateral Neuralgiform headache with Conjunctival injection and Tearing (SUNCT) Short-lasting Unilateral Neuralgiform headache with Conjunctival injection and Tearing (SUNCT) syndrome is a rare type of headache belonging to the group of headaches called trigeminal autonomic cephalalgia (TACs). Patients experience excruciating burning, stabbing, or electrical headache mainly in orbital area along with cranial autonomic signs that are unique to SUNCT. Each attack can last from 5 seconds to 6 minutes and may occur up to 200 times daily. Onset of the symptoms is usually late at an average age of 50. Although majority of patients are males above ages of 50, it is not uncommon to find patients that do not belong such group, including children and infants.

Symptoms
Sufferers of SUNCT often describe their headache attacks as "the most excruciating pain" and often rate its magnitude of pain as 9 out of 10 (10 being the most painful). The attacks are severe enough to disrupt daily activities, but hospitalization is not necessary. The average attacks per day is around 60, ranging from 3 to 200 times.

The attacks can be grouped into three groups: stabs, stab group, and saw-tooth, from the shortest to the longest duration respectively. The attacks usually last from 5 seconds to 240 seconds. Typically, longer attacks are more painful due to psychological effects and patients often feel agitated before and during the attack.

They occur mostly in orbital, supraorbital or temporal region and also can occur in the retro-orbital region, side, top, back of head, second and third trigeminal divisions, teeth, neck and ear.

SUNCT syndrome often accompanies cranial autonomic symptoms, including lacrimation, ipsilateral ptosis eyelid edema, nasal blockage, conjuctival injection and tearing. Seldom, attacks occur without any of the cranial symptoms as in short-lasting unilateral neuralgiform headache attacks with cranial autonomic features (SUNA). Majority of SUNCT attacks occur chronically, however, some occur episodically. In chronic SUNCT, the attaks can occur regulary or irregularly through out the year with not destinct refractory period whereas in episodic SUNCT, symptoms occur only for a certain period and cease for another period. The episodes of attacks last from a few days to a few months and up to 22 attack episodes in one year have been observed. SUNCT can go into remission even after chronic period and relapse either with some stimuli or simultaneously.

Triggers
Most of the time SUNCT occurs spontaneously, however the attacks can be triggered by simple daily stimuli such as touching the face or scalp, washing, shaving, chewing, eating, brushing teeth, talking, coughing, washing or brushing the hair, light (including sunlight and fluorescent lights), blowing the nose, exercise and showering as well as injuries. Some stimuli capable of triggering cluster headache including alcohol, smoke, strong smells and a warm environment can also trigger SUNCT in a few patients. In some cases, patients of episodic SUNCT exhibit symptoms biannually only in spring and fall. This periodicity suggests a role of hypothalamus in its triggering.

The first case
In 1977, a 62 year old male patient was first diagnosed as SUNCT. The patient had developed unilateral, mild pain in ocular and periorbital area since he was 30 years old. But he started to experience more severe attacks after a struck with a fishing rod in lower, medial, supraorbital area when he was 58 years old. The attacks could be provoked with mechanical stimuli and ocurred more frequently with conjuctival injection, lacrimation, and rhinorrhea. The definite diagnosis and the determination of the role of the trauma (fishinf rod struck) could not be made until there was another similar case, in 10 years. Conditions of the next cases ruled out the possibility of a posttraumatic headache for SUNCT.

IHS criteria
SUNCT must be properly distinguished from cluster headaches, since they also occur several times per day for separate attacks, and share some common symptoms. However cluster headaches usually last longer (up to 3 hours), occur less often (3-5 attacks/day), and does not accompany cranial autonomic symptoms. IHS standard criteria for diagnosis of SUNCT syndrome specifically includes pain in trigeminal division in face, especially in orbital region often with cranial autonomic symptoms which lasts for relatively short period of time (5 seconds to minutes) up to 100 times per day. SUNCT is a major subset of SUNA, which does not accompany cranial symptoms; complete separation between the two is inappropriate since SUNCT does not necessarily always accompany cranial autonomic signs. Exact statistic data is not available due to common mis-diagnosis, and setting up diagnostic criteria is important.

The International Headache Classification by International Headache Society criteria for diagnosing SUNCT for therapeutic purpose are:


 * (i) Type of attack – Attacks of unilateral orbital, supraorbital or temporal stabbing or pulsating pain accompanies by ipsilateral conjuctival injection and lacrimation


 * (ii) Number of attacks per day – 3 to 200 attacks per day


 * (iii) Attack load in minutes per day – 5-240 seconds

Symptoms of SUNCT often also lead to misdiagnosis as paroxysmal hemicrania which is also categorized in the same group. Inefficiency of indomethacin usually indicates SUNCT over paroxysmal hemicrania.

The following chart is summary of hierarchical classification of SUNCT:

Misdiagnosis and indecisive diagnosis in the past has made obtaining accurate statistics about SUNCT difficult.

Pathophysiology
Pathophysiology of SUNCT syndrome has not been fully understood. However, recent studies suggested the existence of relationship between hypothalamus with the condition. Functioning imaging and deep brain stimulation of large patient pool showed activation of posterior hypothalamus during attacks of primary SUNCT, both bilaterally and contralaterally. Functional MRI study also suggested brainstem activation during attacks as well. Activation of the trigeminocervical complex and other related structures results from innervation from branches of trigeminal and upper cervical nerves. There exists a direct connection between trigeminal nucleus caudalis which is located in the brainstem and the posterior hypothalamus. Therefore it is possible that stimulation of the peripheral trigeminal nerve activates the hypothalamus and hypothalamus in turn communicate with the trigeminal nucleus caudalis via neurotransmitter such as orexin.

Elevated level of prolactin, which its secretion is regulated by hypohthalamus, seems to be associated with SUNCT attacks. Some patients with pituitary tumor only experienced attacks during nighttime. They only exhibited higher level of prolactin during nighttime where hormone levels including prolactin was normal through out the day.

SUNCT syndrome is a primary headache but it also occurs as secondary symptom of different conditions. Pituitary tumor causes SUNCT as a secondary headache. Some patients with pituitary tumor complained of short-lasting heachaches and upon removal of the tumor, the symptoms of SUNCT coul also be abolished.

Although it occurs very rarely, Ppranasal sinusitis can also cause secondary SUNCT. The symptoms of SUNCT was abolished upon endoscopic sinus surgery.

Treatments
Diagnosis criteria had been indecisive and its pathophysiology still unknown, currently there is no permanent cure available. Though antiepileptic drugs (membrane-stabilizing drugs) such as Gabapentin, Topiramate, and Lamotrigine improve symptoms, there is no effective permanent or long-term treatment for SUNCT. However, a few short-term treatments are available and can relieve symptoms of attacks and possiblly prevent some.

Lamotrigine exhibit some long-term prevention and reduction in many patients; however titration of dose is difficult due to adverse skin reactions.

Topiramate also has preventive effects but it accompanies high risk of severe side-effects for patients with a history of renal stones, glaucoma, depression or low body weight.

Intravenuous lidocaine can also abolish symptoms during its administration or reduce frequency and duration of attacks. However, administration of intravenuous lidocaine requires careful monitoring of ECG and blood pressure. Methylprednisolone therapy shows some promise in short-term prevention of attacks, even though its mechanism of action is yet to be discovered. Verapamil, despite the fact that some patients experienced worsened symptoms, has been reported to be useful in alleviating symptoms - lower frequency and duration.

There has been attempt to alter oxygen supply during attacks to alleviate the symptoms; however elevated blood oxygen level did not affect the conditions.

Researches now focus on administration of various combination of different medications and therapies to treat symptoms of SUNCT.