size that the thoracolumbar interfascial plane (TLIP) block may provide more focused analgesia and may be superior to ESP block in this clinical setting. However, based on the available evidence, at this point in time it is difficult to argue that either of these techniques is consistently superior for analgesia in lumbar spine surgery. In the original description of ESP block, Forero et al3 demonstrated that extensive analgesia of the hemithorax could be obtained by depositing a volume of local anesthetic either superficial or deep to the erector spinae muscle. In the vast majority of subsequent literature, deposition of local anesthetic deep to the erector spinae muscle has become standard. The mechanism of action of the ESP block is still not fully elucidated; possibilities include diffuse cutaneous, paravertebral, or epidural spread of local anesthetic. If local anesthetic deposited superficially to the erector spinae muscle can result in analgesia over most of the hemithorax (even if it is less effective or of shorter duration of action compared with local anesthetic placed deep to the erector spinae), it makes logical sense to assume that it is equally possible that injectate deposited in the TLIP could result in paravertebral or diffuse cutaneous spread. In other words, until subjected to formal investigation using robust scientific methodology, it is not possible to determine which, if either, of TLIP or ESP blocks is superior in lumbar spine (and other) surgery. With the ESP block, there is inconsistency in the pattern of effective blockade between individuals and between studies. For example, some studies have consistently shown anterior cutaneous sparing following ESP block,4 whereas others have reported circumferential sensory loss following bilateral ESP block.5 Possible explanations for these variations include the anatomic complexity of the thoracolumbar fascia, the complex 3-dimensional geometry of the erector spinae muscle group (which changes along its length), volume of injectate administered, and differences in operator technique. I agree with Tseng and Xu that the dorsal rami are the nerves of interest in lumbar spine surgery and that the TLIP block warrants further study. The idea that TLIP block prevents local anesthetic washout is an interesting concept worthy of further investigation. It does seem unlikely that involvement of the ventral ramus would result in delayed ambulation. However, there are anecdotal reports suggesting that lower limb weakness may occur following lumbar ESP block,6 presumably due to spread of local anesthetic to the lumbar plexus. It is also possible that such spread could occur following TLIP block. The one thing we can be certain about is that there are exciting opportunities ahead for investigators who are working to unravel the mechanistic details of these competing truncal fascial plane blocks.

Vein of Galen malformations (VOGMs) are rare anomalies of intracranial circulation that constitute 1% of all intracranial vascular malformations. However, they represent 30% of vascular malformations presenting in the paediatric age group.[1] These lesions are characterised by the presence of an aneurysmally dilated midline deep venous structure, fed by abnormal arteriovenous communications. The venous system of the brain is mal-developed many venous anomalies can associate with VOGM. We describe a case of VOGM in which there was hypoplasia of the right internal jugular vein (IJV) leading to failure in the placement of central venous catheter through right IJV.

Jain, Virendra MD, DM; Prakash, Prabhakar S. MD; Dash, Hari H. MD, MNMS Author Information

Editor, Pneumocephalus, or air within the intracranial cavity, is a common occurrence after the cranial surgery [1]. Tension pneumocephalus in the posterior fossa compressing brain stem is previously reported in the sitting [2] or prone position [3]. To the best of our knowledge, it has not been reported in the supine position. We report a case of brain stem tension pneumocephalus after craniotomy for chronic subdural haematoma (SDH) evacuation performed in supine position. Increase in the intracranial pressure due to pneumocephalus leads to postoperative respiratory distress requiring mechanical ventilation. A 54-year-old, 70-kg man admitted with bilateral chronic SDH was scheduled for left craniotomy and haematoma evacuation, followed by burr hole evacuation of haematoma on the right side under general anaesthesia. All preoperative investigations including pulmonary function tests were within normal limits. After informed consent, routine monitoring was instituted, and anaesthesia was induced. Anaesthesia was maintained with 60% air in oxygen and propofol infusion with intermittent doses of fentanyl and vecuronium. Arterial blood gas tension was normal (pH 7.43, paO2 104.2 mmHg, paCO2 38 mmHg) following intubation. After the frontal craniotomy and haematoma evacuation on the left side, the head was turned to the right for burr hole and haematoma evacuation. During the burr hole evacuation, the head end of the table was tilted about 45° above heart level and then backwards to facilitate evacuation of haematoma. The table was tilted two more times within the next 10 min again at the surgeon's request. Total duration of surgery was 90 min. The intraoperative period was uneventful. At the end of surgery, neuromuscular block was reversed with neostigmine and glycopyrrolate. The trachea was extubated, and the patient was fully awake and following commands. Head lift and handgrip were adequate. Thereafter, the patient was shifted to the ICU. Within 10 min of shifting to the ICU, the patient became restless and irritable, and respiration became irregular and shallow. At that time, pulse was 100 beats min−1, blood pressure 140/86 mmHg, respiratory rate 30 breaths min−1 and SpO2 100%. Auscultation of the chest was unremarkable. Arterial blood gas tension showed pH 7.23, paO2 260.6 mmHg and paCO2 67.8 mmHg. In view of the high paCO2, the respiration was supported by bag and mask. However, even after 5 min, the patient's clinical condition did not improve. He was drowsy and responding only to painful stimulus. It was then decided to initiate mechanical ventilation. The trachea was intubated after giving propofol 100 mg intravenously (i.v.) and rocuronium 70 mg i.v. An urgent computed tomography (CT) of the head was done that revealed air around the brain stem (Fig. 1). The patient was sedated with propofol infusion and ventilated overnight. The following morning, a repeat CT was done that showed that the air around the brain stem had resolved. Neurological response was assessed after stopping sedation. He was conscious following verbal commands and moving all four limbs. The patient was thereafter weaned off the ventilator and extubated. He was discharged from hospital on the third postoperative day with intact neurological status.Fig. 1Tension pneumocephalus is not a rare complication of neurosurgical procedures. Tension pneumocephalus may present as deterioration in the level of consciousness, with or without focal signs, restlessness, generalized convulsions or even cardiac arrest [4]. Posterior fossa tension pneumocephalus has been reported previously after surgery performed in sitting [2], prone [3] and even lateral position [5]. In our case, posterior fossa tension pneumocephalus occurred in supine position. The probable mechanism causing air collection near the brain stem could have been as follows – initially, a craniotomy for left-sided haematoma evacuation was carried out. Inspite of all precautions (isotonic saline instillation before dura closure, keeping drainage site at the lowest point of head) being taken, air may have still collected in the left frontal region. The head was thereafter turned to the left for the burr hole evacuation of the haematoma on the right side. The table was tilted thrice upwards and downwards to facilitate the haematoma evacuation. During the head turning or table tilting, the air may have transgressed from the supratentorial compartment to the infratentorial compartment. When the patient was reversed, a transient rise in the intracranial pressure would have occurred leading to conversion of pneumocephalus to tension pneumocephalus. This tension pneumocephalus could have caused compression on the brain stem leading to irregularity in respiration. The other possibility could have been an inadequate reversal of the neuromuscular blockade. As neuromuscular monitoring was continuously performed until reversal, this possibility of residual neuromuscular paralysis is unlikely. Aspiration of air is the treatment of choice for emergency decompression of tension pneumocephalus. Toung et al. [6] have described four cases of tension pneumocephalus after posterior fossa surgery. In all cases but one, surgical aspiration improved the neurological status. Aspiration was not considered in our case, as the location of the air was near the vital structure in the brain stem. Instead, we initiated mechanical ventilation to tackle the respiratory distress with irritable behaviour (probably due to high paCO2) so as to allow the tension pneumocephalus to resolve spontaneously. The posterior fossa is a narrow space with small volume. Therefore, even a small quantity of collected air, as in our case, could have led to a significant increase in the intracranial pressure. Hence, in the event of respiratory distress following craniotomy, the possibility of tension pneumocephalus in posterior fossa should be considered.