The autonomic nervous system consists of the sympathetic and parasympathetic nervous systems. The sympathetic nervous system is involved in situations where an immediate reaction is needed from the body and in addition plays the role of a mediator in painful situations and pathologies. Painful conditions in which the sympathetic system is believed to be involved respond therapeutically to blocking of the corresponding sympathetic fibers. Blockade of sympathetic ganglia is a century old method, practiced since the first world war for analgesia. Sympathetic ganglia involvement is known to be involved in the pathophysiology of various painful conditions. One of the proposed mechanisms is the elimination of normal inhibitory action on pain. Adrenergic overstimulation is considered to be responsible for some of the symptoms. The effects of ganglion blocks in these conditions usually exceed the duration of action of the agents used. This suggests that blocks of sympathetic neurons interrupts the positive feedback loop and reduces central hyperexcitability. Because of their effectiveness and ability to alter afferent signals from the peripheral to the central nervous system, sympathetic blocks have been used in painful conditions such as postherpetic neuralgia and some non-painful ones as well, such as post-traumatic stress disorder (PTSD) and hyperhydrosis.
The sphenopalatine ganglion is a predominantly parasympathetic center with multiple connections to the trigeminal, parasympathetic, and sympathetic systems. Because of its complex nature, sphenopalatine ganglion block has been used for a variety of medical conditions in the past from low back pain to treating asthma. Today it is mainly used in the treatment of persistent face pain, migraine, cluster headache, while it has also been used for trigeminal neuralgia, head and neck cancer and myofascial pain.
Due to the low efficacy of drug therapy in episodic headache, blockade of the sphenopalatine ganglion has become an essential therapeutic intervention. It is also used in patients with head and neck cancer. These patients suffer from intractable headaches and facial pain. Sphenopalatine ganglion block has been increasingly used in these patients in recent years. In conclusion Sphenopalatine ganglion block is a safe method of treating intractable facial pain and diverse origin’s headaches.
There are two sympathetic chains bilaterally, paravertebrally, part of the peripheral autonomic nervous system. In the neck region these include four sympathetic ganglia on each side which act as cholinergic control centers, the superior and middle cervical ganglion, the vertebral ganglion and the stellate ganglion.
Their blockade is a useful method of pain treatment in patients with perfusion disorders in the areas of the head, neck, upper extremities and upper chest wall. The following indications have been described in the literature: Vasospastic diseases in the areas of the face, shoulder and arm. Arterial and venous dysfunction syndromes and complex syndromes such as post-mastectomy lymphedema. Intracranial spasms, facial nerve paralysis, vertigo, central post stroke syndrome, central vein thrombosis, central retinal artery occlusion. Vasomotor rhinitis in the nose. In the ear, Menniére’s disease, sudden deafness, tinnitus, traumatic brain edema, complex regional syndrome in the areas of the face, neck, arm and hand, phantom limb pain, hyperhidrosis, joint stiffness. Positive effects on the immune system are also reported. Acute herpes zoster and postherpetic neuralgia in the face and neck area are also treated. Studies published in the last five years show positive results of their use in symptom reduction and clinical improvement of people with Post-Traumatic Stress Disorder.
It is reported in the literature that the shorter the duration of the disease during the injection, the greater the success of gagglion blocks.
Regarding ultrasound guided injection that has been used more and more in recent years, literature reports indicate a smaller required volume of local anesthetic, shorter onset, lower possibility of complications and improved efficacy, making it valuable for treatment outcome.
