Efficacy Of Ultrasound Guided Stellate Ganglion Block To Relieve Vasospasm Following Clipping Of Cerebral Aneurysm

Anesthesiologist was informed about the patients (Post clipping for cerebral aneurysm) having neurological deterioration (hemiparesis, aphasia, apraxia, hemianopia, or neglect), or a decrease of ≥ 2 points on the Glasgow Coma Scale(GCS) and in whom the duration of symptoms lasted for at least 1 hour. Anesthesiologist was also informed if increased cerebral blood flow velocity was found on routine daily Transcranial Doppler(TCD) evaluation of such patients. A cerebral Computed tomography(CT) scan was performed at this time to rule out ventricular dilation or any other focal brain lesion explaining the clinical symptoms. In such patient Central venous pressure(CVP) was maintained at 8-10 mm of Hg and systolic blood pressure was maintained between 160-200 mm Hg (using infusion of vasopressors such as phenylephrine or dopamine if required). Oral/ nasogastric nimodipine (60 mg 4 hourly) was continued and hemoglobin was maintained at ≥ 10 gm/dl.

Diagnosis Of Vasospasm By Transcranial Doppler A 2 megahertz (MHz) transcranial Doppler ultrasound probe was used to insonate vessels through the temporal acoustic window. Extracranial Internal Carotid Artery (ICA) was insonated in the neck using a linear probe of 8- 13 MHz. Using Transcranial Doppler (TCD) probe, a tracing of waveform of Middle Cerebral Artery (MCA) was identified and confirmed using standard criteria. Peak Systolic Velocity and Mean Flow Velocity were assessed. Pulsatility Index and Resistivity Index were assessed. LINDEGAARD ratio was calculated.

Diagnosis Of Vasospasm By Digital Subtraction Angiography (DSA) Patients were shifted to Digital subtraction Angiography room and an emergency cerebral angiographic study was performed using Philips Allura Xper FD20/10 machine. Vasospasm was diagnosed on DSA and the vessel diameter was measured at the mid A1 segment of Anterior cerebral artery(ACA) and mid M1 segment of Middle Cerebral Artery (MCA). Vasospasm was classified as mild (<25%), moderate (25% to 50%), or severe (>50%) with respect to two - dimensional diameter at the mid A1 and mid M1 segment of ACA and MCA respectively. Location of vasospasm was classified as unilateral vs bilateral, single vessel involvement vs multiple vessel involvement or diffuse vasospasm (bilateral with multiple vessel involvement). Parenchymal filling time was calculated as the time delay between initiation of contrast injection till the appearance of parenchymal blush. Venous sinus filling time was calculated as the time delay between the initiation of contrast injection till the appearance of superior sagittal sinus. After diagnosis of vasospasm patients were administered ultrasound guided Stellate Ganglion block using 10 ml of 0.5% Injection Bupivacaine on the same side of vasospasm or the side contralateral to the focal neurological deficit.

Ultrasound Guided Stellate Ganglion Block - Technique Patients were kept supine with the neck in slight hyperextension. Under aseptic conditions, transducer is placed on the surface of the neck at the level of Cervical (C6) vertebrae. The internal jugular vein, carotid artery, thyroid gland, trachea, C6 vertebrae, transverse process of C6, esophagus, longus colli with its covering prevertebral fascia and esophagus are visualized. The transducer was pressed between the trachea and the carotid artery to retract the artery laterally as well as to position the transducer near the longus colli. A 25-gauge Quincke spinal needle was inserted paratracheal towards the middle of the longus colli muscle. The endpoint of the injection was the ultrasound image of the tip of the needle as it penetrates the prevertebral fascia covering the longus colli muscle. The drug is then injected and spread of drug is visualized as distension of prevertebral fascia around the longus colli muscle in real time.

Post Block Assessment-