Superior Cervical Ganglion Block, Transcranial Doppler

The aim of this study is to assess blood flow velocity in middle cerebral artery measured by transcranial doppler to determine the efficacy of SCG block in decreasing incidence or severity of vasospasm after MCA aneurysm surgery.

Sympathetic innervation to the face and head is by superior cervical ganglion(SCG), which is the most cranial part of the sympathetic chain. It is suited in a plication of the prevertebral fascia anterior to the longuscapitis muscle and dorsal to the internal carotid artery, posteromedial to the vagus nerve at c3 level. It's mainly located at the level of the transverse processes of the second and third cervical vertebrae. However, it may reach caudally to the upper border of the fourth cervical vertebra.

Noradrenergic sympathetic nerve fibers mainly originating in the superior cervical ganglion, accompanying the carotid artery supply cerebral vasculature particularly the pial vessels.

Superior cervical ganglion block was previously tried in managing neuropathic pain, neuropathic pain in head and face region was investigated in patients using ganglionic local opioid analgesia (GLOA) at the superior cervical ganglion (SCG) ,The short-term analgesic effect of the first blockade by GLOA was significant with a mean pain reduction of 52% (p \< 0.001).

Superior cervical ganglion block also used as an alternative treatment to tinnitus not responding to conventional therapy, it increases cholear blood flow and this can explain the efficacy of block.

Superior cervical ganglion block was used to improve cerebral perfusion in patients with cerebral vasospasm after aSAH.

Aneurysmal subarachnoid hemorrhage (aSAH) may develop vasospasm in 70% of patients. Morphological changes occur in the cerebral vessels after SAH, and the inflammatory response and local chemical agents are responsible for the induction of vasospasm.

Vasospasm is rare in the first 3 days after SAH, it reaches peak incidence at 7 to10 days and usually resolves by 10 to14 days after SAH.

The sympathetic system also has a role in the pathogenesis of this process, cervical sympathetic stimulation leads to constriction in intracerebral vessels and dilation occurs when these fibers are interrupted. Efflux and reuptake of the neurotransmitter may be prevented by sympathectomy.

Common treatments to reduce vasospasm include ;triple H therapy (hypertension ,hypervolemia and hemodilution), intraarterial infusion of Smooth muscle relaxants (papaverine, Verapamil) and endovascular balloon angioplasty . Also (nimodipine) calcium channel blocker administration is used as a prophylactic measures.

Transcranial doppler (TCD) is a non-invasive technique which can be used to observe velocity, direction and properties of blood flow in the cerebral arteries by means of a pulsed ultrasonic beam, based on the Doppler effect of ultrasounds concerning frequency variations in sound waves as a result of relative motion between source and signal receiver. It was previously used in traumatic brain injury(TBI),stroke, anesthesia and intensive care.

Eligibility Criteria:
Inclusion Criteria:

* Patients aged from 18 to 70 years.
* Genders eligible for study: both sexes.
* ASA I-II.
* GCS (13-15)

Exclusion Criteria:

* Patient refusal
* Contraindications to regional anesthesia (Bleeding disorders, Use of any anti-coagulants, local infection).
* Known allergy to local anesthetics.
* ASA III-IV.
* Patients aged less than 18 or more than 70.