Patent Publication Number: US-11653908-B2

Title: Apparatus and method for retracting brain tissue during brain surgery

Description:
RELATED APPLICATIONS 
     This application is a continuation of application U.S. Ser. No. 16/373,888, filed Apr. 3, 2019, which is incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND 
     A brain surgeon performing surgery through an opening created in the skull, is typically faced with the challenge of pushing brain tissue out of the way of a target surgical location and restraining the brain tissue during surgery. In many surgical situations, this is done by finding a natural cleft between the lobes, working a pair of spatulas into the cleft and then separating the spatulas to separate the brain tissue. To keep the tissue separated as the surgeon operates, the spatulas must be held in place. This is typically done by arms that are attached to some article that is held in constant position, relative to the patient&#39;s head. Most typically, the arms are attached to the clamp that is used to stabilize the patients head during surgery, but in some cases the arms are attached to the surgical table. One disadvantage of these arrangements is that a long arm is necessary to reach from its mount. It is difficult to obtain the desired stability with such a long arm, and it may even obstruct the freedom of movement of the brain surgeon. 
     SUMMARY 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
     In one aspect, the present invention may take the form of a method of performing brain surgery on a patient having a skull and brain tissue, that starts by creating an opening, having a rim, in the skull. The method uses an assembly for facilitating brain surgery that includes a curved frame, defining an inward dimension and an outward dimension; a plurality of spatula arm subassemblies, each including a spatula arm frame clamp, releasably attached to the frame, a spatula arm held and supported by the spatula arm frame clamp and a spatula extending from the inward end of the spatula arm of the spatula arm subassembly. The assembly is clamped to the rim and the spatula arms are positioned so that the spatulas engage the brain tissue in a manner that facilitates surgery. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments are illustrated in referenced drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
         FIG.  1    shows an isometric view of a brain tissue retractor assembly, according to the present invention. 
         FIG.  2    shows an exploded perspective view of a spatula arm assembly, that forms a part of the brain tissue retractor assembly of  FIG.  1   . 
         FIG.  3    shows an exploded perspective view of a skull clamp arm assembly, that forms a part of the brain tissue retractor assembly of  FIG.  1   . 
         FIG.  4    shows a sectional view of a clamp arm lock, which forms a part of the skull clamp arm assembly of  FIG.  3   . 
         FIG.  5    shows a sectional view of a portion of the clamp arm assembly of  FIG.  3   , clamped to the frame of the brain tissue retractor assembly, of  FIG.  1     
         FIG.  6    is a detail sectional view of a portion of the spatula arm assembly of  FIG.  2   . 
         FIG.  7    is a detail partial sectional view of a portion of the brain tissue retractor assembly of  FIG.  1   , clamped to skull bone and spreading apart brain tissue. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG.  1   , in a first preferred embodiment, a brain tissue retraction assembly  110  takes the form of a hinged circular frame  112 , having a set of releasably attached clamp arm-subassemblies  114  and releasably attached spatula-arm-sub-assemblies  116 . Frame  112  defines an interior or inner direction, meaning further to the interior of the frame, and an exterior or outer dimension, meaning away from the interior of the frame, or further outside of the frame. Frame  112  is divided into two semicircular pieces  112   a , hinged together by a pair of hinges  112   b , which can be each be locked into position by a frame wing bolt  112   c.    
     Referring to  FIGS.  3  and  5   , each clamp arm-sub-assembly  114  includes a clamp arm base  118 , having a lock plate  118   a  that is opposed to a dog  118   b , protruding up from a dog plate  118   c . If a portion of frame  112  is interposed between plate  118   a  and dog  118   b  and a wing bolt  118   d  is tightened down, then frame  112  is held tightly between dog  118   b  and plate  118   a . When wing bolt  118   d  is loosened, frame  112  is released from pressure and base  118  may be moved about frame  112  or removed entirely. A clamp arm  120  is slidingly engaged in a through-hole  118   e  in base block  118   f  and may be locked in place by locking lever  118   g . In a preferred embodiment, frame  112  is semicircular in cross-section, so that the mutually opposed surfaces of member  118   a  and dog  118   b  fit conformally about from frame  112 . 
     Each clamp arm terminates at its interior end in a clamp head  122 , having a tongue  124  that is brought closer to clamp head by a bolt  126 , threaded through a hole in clamp head  122  and then helically engaged in a threaded hold in tongue  124 , to tighten tongue  124  and clamp head  122  about the rim of a hole created in the skull, thereby holding frame  112  in place. Bolt  126  is loosened to loosen tongue  124  and head  122  from about the skull, to permit removal of the clamp head  122  and of the overall retraction assembly  110 . Also, tongue  124  can be rotated relative to head  122 , before being tightened into place by bolt  126 . In one embodiment, the upper surface of tongue  124  and the lower surface of head  122  have a coating of a biocompatible and resiliently deformable material, such as silicone, to conform to the upper and lower surfaces of the skull hole rim. it is notable, however, that restraining brain tissue cannot apply a great force against the skull hole rim, as brain tissue is soft and pliable. Accordingly, every element of assembly  110  may be made of lightweight material and in thicknesses that do not provide the strength that might be necessary in other applications, but that are thin enough so that assembly  110  has a mass of, in one embodiment, less than 100 grams. 
     Referring to  FIGS.  2  and  6   , each spatula arm subassembly  116  includes a spatula-arm-base  150 , including a base block  150   a , and a clamping block  150   b  that includes an upwardly projecting dog  150   c . A clamping wing bolt  150   d  is engaged into a threaded opening, which draws clamping block  150   b  towards base block  150   a , when turned in a first direction, thereby clamping blocks  150   a  and  150   b  about frame  112 . When wing bolt  150   d  is turned in the opposite direction, base  150  is loosened from frame  112 , for movement along frame  112 , or removal from frame  112 . A spatula arm  154  is held in place between two vertically rotatably-ears  156 , which are in turn held between two wings  158  of a mounting bracket  160 . A locking wing bolt  162  is tightened to hold spatula arm  154  in place, so that it cannot be moved inwardly and outwardly, and to hold ears  156  in place by pressure from wings  158 , so that ears  156  cannot be rotated vertically, which would thereby vertically rotate arm  154 . In addition, bracket  160  is mounted to base  150  so that it can be horizontally rotated, thereby horizontally rotating arm  154 . A locking ring  162  is rotatable and helically threaded engagement to a bolt  164 , permitting ring  162  to be tightened down against base block  150   a , thereby locking bracket  160 , and thereby arm  154 , in place against horizontal rotation. A spatula  170  extends downwardly at the end of arm  154 . 
     In an alternative preferred embodiment spatula arms that are deformable and that hold their shape after deformation are provided. These arms are deformed into position, holding spatulas to restrain the brain tissue. 
     Referring to  FIGS.  1  and  7   , to use assembly  110 , clamp arm-sub-assemblies  114  are moved on frame  112  and each clamp arm  120  is moved relative its base  118 , until clamp heads  122  are arranged about the rim  210  of a hole in the patient&#39;s skull, and sub-assemblies  114  and arms  120  are locked in place, and clamp heads  122  and tongues  124  are tightened about the rim  210 , to hold assembly  110  in place. With spatula arms  154  in an upwardly tilting orientation, the spatula arm subassemblies  116  are arranged in placement on frame  112 , so that spatulas  170  may be at a correct location and orientation when lowered into place. Spatula arms  154  are rotated horizontally so that each spatula  170  is oriented along a cleft in the brain tissue  212 . Then (step not shown), while the brain tissue is gently manually retracted, spatula arms  154  are vertically rotated down to place spatulas  170  so that they will continue to restrain the brain tissue  210  (as shown) when it is no longer manually restrained. Spatulas  170 , in one embodiment, are made of a thin sheet of metal, that is resiliently deformable. Other materials may be used. 
     In one preferred embodiment, frame  112  is 18 cm (7 in) across at the hinges, and 16 cm (6.5 in) across in the orthogonal dimension. The frame defines an interior round area, having a diameter of about 15.24 cm (6 in.), for an interior area of about 730 cm. In a preferred embodiment, frame  112  is made of stainless steel, as are the subassemblies. 
     While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.