Rajendra Singh Chouhan

Comparative incidence of venous air embolism and associated hypotension in adults and children operated for neurosurgery in the sitting position

Background and objective: Venous air embolism is a constant threat during neurosurgery performed in the sitting position. No large prospective study has compared the incidence of venous air embolism and associated hypotension between adults and children. Methods: Four hundred and thirty patients (334 adults, 96 children) scheduled to undergo planned posterior fossa surgery in the sitting position (between January 1989 to December 1994) were studied with end-tidal carbon dioxide monitoring. Intraoperatively, a sudden and sustained decrease in end-tidal carbon dioxide tension of >0.7 kPa was presumed to be due to venous air embolism. Management during the episode was on the established guidelines. Hypotension (decrease in systolic arterial pressure of 20% or more from the previous level) was treated with crystalloids and/or a vasopressor. Results: Capnometry detected a 28% incidence rate of air embolism in adults (93/334) and a 22% incidence rate in children (21/96) (P = 0.29). In both groups, the highest incidence rate of embolism took place during muscle handling (44% of adults versus 38% of children, P = 0.8). Embolic episodes were accompanied by hypotension in 37% of adults (34/93) and in 33% of children (7/21) (P = 0.98). To restore arterial pressure to pre-embolic levels, 53% of adults (18/34) and 43% of children (3/7) were administered vasopressors (P = 0.94). There was no intraoperative mortality. The surgical procedure on one adult was abandoned because of persistent hypotension following the embolic episode. Conclusion: The incidence of venous air embolism and consequent hypotension is similar in adults and children.

Sudden asystole during surgery in the cerebellopontine angle

SummaryWe report a case of a 40-year-old lady undergoing surgery for a tumor in the cerebellopontine angle. Intraoperatively, patient had a sudden asystole without prior warning sign of bradycardia. It could have been the severe form of trigeminocardiac reflex. The cardiac rhythm returned spontaneously once the surgical manipulation stopped. The remainder of the operation was uneventful and no complication occurred afterwards. The possible mechanism of the event is discussed.

ECG changes in pediatric patients with severe head injury.

&NA; Although ECG changes in subarachnoid hemorrhage and head injury have been described in adults, they have been rarely reported in children. We present 3 pediatric head‐injured patients who developed severe ischemic changes on ECG. Three children (ages 9 months, 2.5 years, and 12 years) were admitted with severe head injury. All of them developed progressive ST segment depression of 4 to 7 mm during the surgical procedure. The first case, a 9‐month‐old child, also had bradycardia and cardiac arrest following ST depression. He was promptly resuscitated with simultaneous evacuation of extradural hematoma. In the other two cases, ST depression also gradually came up to baseline coinciding with surgical treatment of main pathology. All of the patients were ventilated postoperatively for 36 to 48 hours and discharged with no neurologic deficit. ECG changes and myocardial ischemia in head‐injured patients have been attributed to extreme sympathetic stimulation and raised intracranial pressure in adults. But there has been no such systematic study in children. From our observations, we can conclude that ECG changes do occur in children with head injury, although the exact mechanism awaits further evaluation.

Stellate ganglion block for treatment of cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage - A preliminary study.

Background: Stellate ganglion block improves cerebral perfusion by decreasing the cerebral vascular tone. Its effects on cerebral vasospasm to relieve neurological deficits have not been evaluated. This prospective observational study was carried out to evaluate the effect of stellate ganglion block on cerebral hemodynamics in patients with symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Materials and Methods: Fifteen patients of either sex, aged 18-75 years, who underwent surgical clipping of aneurysm and developed refractory cerebral vasospasm were included. Stellate ganglion block was performed using 10 ml of bupivacaine 0.5% on the side with maximum cerebral blood flow velocity. Neurological status, cerebral blood flow velocity and pulsatility index were assessed before and 10 minutes, 30 minutes, 2 hours, 6 hours, 12 hours and 24 hours after stellate ganglion block. Results: Improved Glasgow coma score was observed 30 minutes after stellate ganglion block. Neurological deficits reduced in 11 patients. Ipsilateral middle cerebral artery mean flow velocity decreased from 133.66 cm/sec before stellate ganglion block to 110.53 cm/sec at 6 hours (P<0.001) and 121.62 cm/sec at 24 hours (P<0.001) after stellate ganglion block. There was a decrease in ipsilateral anterior cerebral artery mean flow velocity after stellate ganglion block (P<0.001), which persisted for 12 hours. A decline in flow velocities was observed in contralateral middle cerebral artery (P=0.008) and anterior cerebral artery (P=0.041) for 12 hours. Conclusion: This study suggests stellate ganglion block to be an effective modality of treatment for refractory cerebral vasospasm after aneurysmal subarachnoid hemorrhage.

Effect of cerebrospinal fluid return on success rate of percutaneous retrogasserian glycerol rhizotomy

Background and Objective Trigeminal neuralgia is a painful syndrome, which has been commonly treated with percutaneous retrogasserian glycerol rhizotomy (PRGR). This study was performed to evaluate the effect of cerebrospinal fluid (CSF) return on the success rate of PRGR. Methods In this retrospective, nonrandomized, observational case series, 100 cases underwent 140 PRGRs under fluoroscopic guidance and were followed up for 6 to 36 months. The results were compared in the presence or absence of CSF return before PRGR. Results The PRGR was successful in 115 procedures (82.1%). CSF return was present in 84 procedures (60%) and, among these, 76 PRGRs (90.5%) produced pain relief. More than 1 year of pain relief without medications was present in 60 of 84 procedures (71.4%). CSF return before PRGR was absent in 56 procedures (40%) and success resulted in 39 procedures (69.6%). Pain relief for more than 1 year without medications was present in 19 procedures (33.9%). The success rate and duration of pain relief was greater in the presence of CSF return compared with absence of CSF return (P ≤ .005). The incidence of complications such as facial dysesthesia (40%), corneal anesthesia (2.8%), herpes simplex (3.5%), and nonbacterial meningitis (0.7%) was not significantly different in 2 groups (P > .05). Conclusion The presence of CSF is an important factor in determining the success rate and duration of pain relief of PRGR.

Comparison of the effects of different anesthetic techniques on electrocorticography in patients undergoing epilepsy surgery – A bispectral index guided study

AIM It is well known that general anesthetics suppress/alter electrocorticography (ECoG) activity. However there are no randomized studies available, comparing various anesthetic techniques as regards their effects on ECoG. METHODS The following is a double blind, randomized cross over study to compare the effects of isoflurane and propofol with or without nitrous oxide on electrocorticographic activity in patients undergoing epilepsy surgery. 40 patients suffering from medically intractable epilepsy scheduled to undergo resective surgery under ECoG guidance under general anesthesia, (March 2008-December 2010) were enrolled. Patients received either isoflurane or propofol (with air/oxygen or nitrous oxide/oxygen) as maintenance agents as per randomization and ECoG was recorded and quantified as per a scoring system (range 1-5, where 5 is most abnormal). RESULTS The mean ECoG score in isoflurane group and propofol with nitrous oxide was 3.0(1.2), 3.2(1.2) [p=0.7] and with air was 3.9(1.0) and 3.4(1.1) [p=0.1] respectively. In both isoflurane group and propofol group addition of nitrous oxide depressed the ECoG score (p ≤ 0.01, 0.5 respectively). The total duration of anesthesia, surgery, emergence time, extubation time, and hospital stay was comparable in two groups. CONCLUSION In our study optimal ECoG recordings were possible with use of either isoflurane or propofol. Addition of nitrous oxide to either of the anesthetic regimens suppressed the ECoG score.

Effect of intraoperative brain protection with propofol on postoperative cognition in patients undergoing temporary clipping during intracranial aneurysm surgery.

BACKGROUND Cognitive dysfunction after subarachnoid hemorrhage (SAH) has been attributable to presence of subarachnoid blood, hydrocephalus (HCP), cerebral edema, vasospasm, and temporary clipping of intracranial aneurysm. Provision of neuroprotection during temporary clipping may improve postoperative cognition in such patients. MATERIALS AND METHODS Good-grade aneurysmal SAH patients undergoing temporary clipping during surgery were allocated either to group C (control) or group P (propofol). Patients in group P received propofol in titrated doses to attain a burst suppression ratio of 75 ± 5% on bispectral index (BIS) monitor. The cognitive function as assessed by Hindi-language modification of mini-mental state examination (HMSE) score was evaluated preoperatively, 24 h after surgery, and at discharge from hospital. A score of ≤23 was indicative of cognitive dysfunction. Perioperative complications, duration of intensive care unit (ICU) and hospital stay, and outcome at discharge were noted. RESULTS A total of 66 patients (32 and 34 in group C and P respectively) were included in the study. 97% of the patients had anterior circulation aneurysms. At 24 h after surgery, eight and 12 patients in group C and P respectively; and at discharge, five patients in each group had cognitive dysfunction. In both groups, the trend showed a decline in cognition at 24 h followed by improvement at discharge. Glasgow outcome score in both the groups was comparable (P > 0.05). Intraoperative brain bulge, postoperative vasospasm, and cerebral infarction were found to be independent risk factors for cognitive dysfunction. CONCLUSIONS Pharmacologic neuroprotection with propofol at the time of temporary clipping during surgery for aneurysmal SAH did not offer any advantage as far as preservation of cognition is concerned.

Is phenytoin administration safe in a hypothermic child

A male neonate with a Chiari malformation and a leaking myelomeningocoele underwent ventriculoperitoneal shunt insertion followed by repair of myelomeningocoele. During anaesthesia and surgery, he inadvertently became moderately hypothermic. Intravenous phenytoin was administered during the later part of the surgery for seizure prophylaxis. Following phenytoin administration, the patient developed acute severe bradycardia, refractory to atropine and adrenaline. The cardiac depressant actions of phenytoin and hypothermia can be additive. Administration of phenytoin in the presence of hypothermia may lead to an adverse cardiac event in children. As phenytoin is a commonly used drug, clinicians need to be aware of this interaction.

Intracranial pressure and haemodynamic changes during the tunnelling phase of ventriculoperitoneal shunt insertion

Background and objective: The tunnelling phase of ventriculoperitoneal shunt insertion is the most painful part but patients are often given inadequate opioid analgesic for fear of post operative delayed recovery and/or respiratory depression. This may result in an increase in intracranial pressure. Methods: Twenty adults scheduled to undergo ventriculoperitoneal shunt insertion were administered standard anaesthesia. Monitoring included heart rate, electrocardiogram, end‐tidal carbon dioxide, invasive blood pressure, and oxygen saturation. Intracranial pressure was monitored by placing the ventricular end of shunt catheter in the dilated lateral ventricle. Five minutes before tunnelling, fentanyl 1 μg kg−1 was administered. Mean arterial pressure, heart rate and intracranial pressure were recorded during tunnelling and subsequently at 1‐min interval for 5 min. Data were analysed using t‐test and repeated measured test. Results: Tunnelling caused significant increase in mean arterial pressure (from 81.4 ± 11.0 to 110.9 ± 15.3 mmHg, P < 0.05), intracranial pressure (from 21.4 ± 8.1 to 29.2 ± 12.5 mmHg, P < 0.05) and heart rate (from 74.4 ± 13.8 to 94.1 ± 17.8 beats min−1, P < 0.05). Whereas, the increase in haemodynamic parameters persisted for 3 min post‐tunnelling, elevated intracranial pressure lasted for 2 min. Conclusion: Tunnelling significantly increases intracranial pressure and blood pressure despite prior fentanyl administration. This may be deleterious in the presence of intracranial pathology.

Does egress of cerebrospinal fluid during percutaneous retrogasserian glycerol rhizotomy influence long term pain relief

Background and Objectives: To examine the effect of cerebrospinal fluid (CSF) flow during percutaneous retrogasserian glycerol rhizotomy (PRGR) on long term pain relief in patients with trigeminal neuralgia. Methods: Eighty‐nine patients with trigeminal neuralgia underwent 102 PRGR procedures. PRGR was conducted under fluoroscopy. After the egress of CSF, anhydrous glycerol (0.3‐0.4 cc) was injected in the sitting position. In the absence of CSF flow, 0.25 mL 2% lidocaine was injected to elicit hypesthesia in the affected side. Once hypesthesia was elicited glycerol was injected. Patients were grouped as A (CSF flow present) or B (CSF flow absent), according to the egress of CSF at the time of needle placement. Patients were followed up for the recurrence of pain (average duration of follow up, 62 months). Results: CSF flow was present in 54 patients (60.6%) and absent in 35 patients (39.4%). Thirty patients (56.6%) of group A had excellent pain relief, 18 patients (33.3%) had good pain relief, and 6 patients (11.1%) had no pain relief. However, in the absence of CSF flow, 14 patients (40%) each had excellent and good pain relief, and 7 patients (20%) were treatment failures. The pain relief was comparable between the groups. The median time to recurrence of pain needing further injection was 66 months in group A and 63 months in group B (not significant). Conclusions: Presence of CSF flow during needle placement does not influence the success rate and duration of pain relief following PRGR.