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|Year : 2019 | Volume
| Issue : 3 | Page : 947-948
The temporal lobe “Paine like” point - angle, depth and haptics too!
George C Vilanilam, Palak Jaiswal, Nithin Raj, Mathew Abraham
Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
|Date of Web Publication||23-Jul-2019|
Dr. George C Vilanilam
Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum - 695 011, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Vilanilam GC, Jaiswal P, Raj N, Abraham M. The temporal lobe “Paine like” point - angle, depth and haptics too!. Neurol India 2019;67:947-8
We were fascinated by Menon and Hegde's novel description  of a “Paine like” point for the temporal horn ventricular tap., The intent behind this new idea, is to reduce the brain bulge during surgical clipping for bled aneurysms, by tapping the temporal horn of the lateral ventricle to release cerebrospinal fluid (CSF), just like one does with the frontal Paine's point.
The key argument favoring this over the traditionally used Paine's point in the frontal lobe, is its safety, as highlighted by the authors. However, we believe that this “Paine like” point is not without its tinge of risks and can be fine-tuned further, taking these three factors into account.
| » Angle of Entry|| |
While the authors describe the cortical surface entry point at 3 cm from the temporal pole to tap the temporal horn, we believe that the angle of access is the key to its safety [Figure 1], [Figure 2], [Figure 3]. The angle subtended by the ventricular tap cannula and the inferior (caudal) cortical surface is a key factor in ensuring the safety of this temporal horn tap. Every angle is a two-dimensional concept with reference to the plane in question. In the neutral head position, this angle (between the cannula and the caudal temporal cortical surface) should be about 65–75% in the coronal plane. A more acute angle (with reference to the temporal base) could miss the temporal horn and transgress the mesial temporal structures, fimbriae of the fornix, mesencephalon, or thalamus. A more obtuse angle could graze the ventricular wall white matter without tapping it and reach the middle cranial fossa floor. The tap being aimed just lateral to the tentorial free edge is another useful practical landmark while doing it. The location of the tentorial edge can be estimated by following the lesser wing of sphenoid in the temporomedial direction.
|Figure 1: Angle of the temporal horn tap on coronal T2 MRI-Angle (71.6 degrees) subtended between the tap trajectory and the vertical towards the temporal base|
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|Figure 3: Angle of right temporal horn tap (coronal-schematic)-65-75%, S-Superior temporal gyrus, M- Middle temporal gyrus, I-Inferior temporal gyrus, OT-Occipito temporal gyrus, CoS-Collateral sulcus, P-Parahippocampal gyrus, Hc-Hippocampus|
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| » Depth Guard|| |
The temporal horn is usually tapped at a depth of 3–3.5 cm from the cortical surface [Figure 2]. Being unmindful of this depth could compromise the safety of this tap. Just as the original Paine's point tap going awry could trangress into the caudate nucleus, this temporal horn tap also calls for abundant caution and experience.
| » Haptics|| |
As with all ventricular “blind taps”, the haptic feedback of a “give way” at the correct depth, angle and the subsequent cerebrospinal fluid (CSF) gush, is an invaluable green signal of procedural safety and success. The bluish thin ependymal lining seen microscopically through a small temporal cortisectomy could also help to avoid a blind tap. Tapping the horn through a small cortisectomy under vision would be safer than a blind tap under the duress of a bulging brain. Thus, we feel that if a blind temporal horn tap is unsuccessful after a couple of attempts, a safer alternative would be to tap the temporal horn by a small middle temporal gyrus cortisectomy under the operating microscope. It is not uncommon to see the use of neuronavigation to access the temporal horn at some centers.
Nevertheless, the concept of a “Paine like” point in the temporal lobe , is an invaluable idea to be implemented with a touch of caution. If Paine et al., could have their “point”, perhaps Menon and Hegde should have their “point” too. Pun not intended.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| » References|| |
Menon G, Hegde A. Tapping the temporal horn – An alternative to Paine's point for intraoperative ventricular puncture. Neurol India 2019;67:305-6.
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Microsurgical anatomy of the temporal lobe: Part 1: Mesial temporal lobe anatomy and its vascular relationships as applied to amygdalohippocampectomy. Neurosurgery 1999;45:549-92.
Paine JT, Batjer HH, Samson D. Intraoperative ventricular puncture. Neurosurgery 1988;22:1107-9.
[Figure 1], [Figure 2], [Figure 3]