Stellate Ganglion Block Using Ultrasound Guidance For Treatment Of Post Clipping Cerebral Vasospasm

The present study has been designed to assess the efficacy and safety of Stellate Ganglion Block (SGB) in relieving symptomatic cerebral vasospasm following aneurysmal clipping. The effect was assessed by both Digital Subtraction Angiography(DSA) and Transcranial Doppler (TCD).

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-

• Development of ipsilateral Horner Syndrome at 5 minutes interval till 30 minutes after block to confirm successful Stellate Ganglion Block.

At thirty minutes after the block the following parameters are assessed:-

* Neurological condition (GCS score, motor deficits, aphasia, apraxia, hemianopia or neglect). Assessment was done by a blinded neurosurgeon.
* Hemodynamic parameters: heart rate, blood pressure
* Transcranial doppler measurement of flow velocity in MCA, Pulsatility index(PI), Resistivity Index(RI) and LINDEGAARD ratio.
* Digital subtraction angiography was repeated to measure diameter of the vessels affected by vasospasm, change in grading of vasospasm, any increase in vessel diameter, parenchymal filling time and venous sinus filling time. Any increase or decrease in parenchymal and venous sinus filling time was noted.

Block Failure- Block was considered a failure if no signs of Horner's syndrome appeared after 30 minutes of SGB block.

Ineffective Stellate ganglion block- Block was considered ineffective after 30 minutes of Stellate ganglion block

* If there was no neurological improvement
* No improvement in Transcranial doppler findings to normal level or no significant change in affected vessel diameter, grading of vasospasm, parenchymal filling time and venous sinus filling time in second Digital subtraction angiography Rescue Management In case of ineffective block, patients were given intra-arterial nimodipine at rate of 0.1 milligram / minute for a maximum dose of 3 milligram /artery as a rescue measure.

Following this improvement, these patients were monitored in Intensive care unit(ICU).

Management Of Patient In Intensive Care Unit

* Avoidance of hypotension. Maintenance of Systolic Blood Pressure(SBP) at 160-200 mm of Hg using vasopressor {(phenylephrine 2-17microgram/Kg/min) and/or (dopamine-5-10 microgram/kg/min)}
* Avoidance of hypovolemia, maintain Central venous pressure at 8-10 mm of Hg
* Maintenance of Hemoglobin ≥ 9gram/decilitre
* Oral/nasogastric Nimodipine 60mg 4 hourly. Clinical course of patients was followed. Baseline neurological, hemodynamic and TCD parameters were reassessed by the anesthesiologist at 30 minutes . Patients with effective block were reassessed for neurological status and flow velocity measurements by Transcranial Doppler at 6 hours, 12 hours, 24 hours, 36 hours and 48 hours after Stellate ganglion block. Patients with ineffective block who received rescue management were not reassessed for neurological status and flow velocity measurements using Transcranial Doppler at various intervals by the anesthesiologist. However the complications occurring in them, the duration of their stay in the hospital and the final outcome in the form of discharge or death was noted.

Complications Of Stellate ganglion block Procedure and drug-related complications were noted.

Complications During Hospital Stay Complications occurring in the post Stellate Ganglion Block period during the entire hospital stay other than those due to the stellate ganglion block per se were noted. Duration of hospital stay was also noted.

Eligibility Criteria:
Inclusion Criteria:

* Any patient with post aneurysm clipping having symptomatic vasospasm i:e new onset of focal neurological impairment such as hemiparesis, aphasia, apraxia, hemianopia, or neglect or decrease of at least 2 points on the Glasgow Coma Scale (GCS) and duration of symptoms lasting for at least 1 hour.
* Transcranial doppler confirmation of vasospasm by measuring cerebral blood flow velocity in MCA and LINDEGAARD ratio.
* Cerebral angiographic confirmation of the presence of vasospasm by Digital subtraction angiography

Exclusion Criteria:

* New onset of focal neurological deficit or deterioration in the level of consciousness due to other causes like re-bleeding, hydrocephalus, cerebral edema, electrolyte disorder, infection and seizure.
* Patients having an infarct on cerebral tomography.
* Patients with clipping of more than one aneurysm.
* Patients with bilateral neurological deficits.
* History of allergy to local anaesthetic agents.
* Refusal of consent.
* Deranged coagulation profile.
* Patients with pre-existing pupillary changes where assessment of effectiveness of Stellate ganglion block will be difficult.
* History of allergy to contrast media.
* Derangement of renal parameters