Patent Description:
Stroke is a common cause of death and disabling neurologic disorder. Approximately <NUM>,<NUM> patients suffer from stroke in the United States every year. Hemorrhagic stroke accounts for <NUM>% of the annual stroke population. Hemorrhagic stroke is due to a rupture of a blood vessel in the brain, causing bleeding into the brain tissue and resulting in a hematoma (a blood mass) in the brain. Prompt removal of the blood mass is necessary to limit or prevent long-term brain injury.

Clear visualization and imaging of the blood mass and any surrounding surgical field facilitates removal of the blood mass. In <CIT> and <CIT>, we disclose cannula with a camera mounted on the proximal end of the cannula with a view into the cannula lumen and the tissue within and below the lumen. In that system, illumination was provided by LED's mounted at the distal end of the cannula, or through fiber optics extending from the proximal end to the distal end of the cannula. <CIT> discloses an endoscope that cannot function as a cannula. <CIT> discloses a light box feeding into a connector rod feeding into tube filled with a fiber optic bundle which in turn feeds into the proximal end of an endoscope, and includes a lens to focus light from the light box into the fiber optic bundle to promote total internal reflection in the fiber optic bundle. <CIT> discloses an endoscope with an image guide extending to the distal end of his endoscope and a light guide that extends to the distal end of the endoscope. <CIT> discloses a cannula for use in conjunction with an endoscope. The cannula has transmissive cannula walls which function as a light guide, with a remote light box providing light to the proximal end of the cannula through a fiber bundle. <CIT> discloses a cannula for use in conjunction with an endoscope, the cannula being configured as a light guide with LED's at the proximal end of the cannula. <CIT> discloses another endoscope with a remote light box feeding into a connector rod feeding into tube filled with a fiber optic bundle which in turn feeds into the proximal end of an endoscope, and includes a lens to focus light from the light box into the fiber optic bundle to promote total internal reflection in the fiber optic bundle.

The devices and methods described below provide for improved visualization of diseased tissue within the body using a cannula system including a cannula with a proximally mounted camera, with illumination provided by light sources mounted to the proximal end of the cannula. The cannula system includes a cannula tube with a camera assembly mounted on the proximal end of the cannula tube, with a viewing axis directed toward the distal end of the cannula to obtain a view of a surgical workspace near the distal end of the cannula tube. To provide adequate lighting while minimizing glare, the cannula system includes powerful packaged LEDs with a broad beam angle combined with additional lenses to focus output of the LED's to a narrow beam angle. Commercially available packaged LEDs, which comprise a LED, a substrate/chip, and a primary lens, are fitted with secondary optics comprising a narrow focusing lens, to reduce the beam angle of the overall assembly. The secondary optics may comprise a GRIN lens, configured to focus light from the LED to a narrow beam angle for transmission through the cannula to the workspace at the distal end of the cannula. For example, for a <NUM> long cannula with a <NUM> inner diameter, the lens may be configured to provide an output beam angle of about <NUM>°.

<FIG>, <FIG> illustrate a cannula system that may be conveniently used in a minimally invasive surgery. <FIG> illustrates a patient <NUM> with diseased tissue <NUM> in the brain <NUM> that necessitates surgical intervention, with a cannula <NUM> which has been inserted into diseased tissue, with the distal end of the cannula proximate the diseased tissue. The diseased tissue may be a glioma or glioblastoma in the brain, an ependymoma in the spine, or other diseased tissue.

A camera <NUM> is mounted on the proximal rim of the cannula, with a portion of the camera overhanging the rim of the cannula and disposed over the lumen of the cannula, and is operable to obtain video or still images of the distal end of the cannula lumen, including target tissue at the distal end of the cannula such as the brain and any diseased tissue in the brain. As shown in both <FIG> and <FIG>, the cannula comprises a cannula tube <NUM> with a distal end 6d adapted for insertion into the body of the patient. The camera assembly <NUM> is secured to the proximal end 6p of the cannula. The camera assembly includes an imaging sensor <NUM> and a prism, reflector or other mirror structure or optical element <NUM>, overhanging the lumen <NUM> of the cannula tube. Preferably, for use in the brain, a portion of the camera assembly, such as the prism, reflector or mirror, extends into the cylindrical space defined by the lumen of the cannula tube and extending proximally beyond the proximal end of the cannula, and is spaced from the proximal end of the cannula, and extends only slightly into the cylindrical space. The distal-most optical surface of the camera assembly, whether it be the distal face of the prism <NUM> or an objective lens with a viewing axis directed toward the distal end of the cannula, used without a prism, is located at the proximal end of the cannula tube, and preferably disposed proximally of the proximal end of the cannula tube.

As shown in <FIG>, the cannula also includes one or more lighting assemblies <NUM> with an output beam axis <NUM>. The lighting assemblies include light sources <NUM> and associated optics, if any, which in the illustration include prisms <NUM> having an output beam axis <NUM> (which in this embodiment is coincident with the output beam axis <NUM> of the lighting assembly), and lenses <NUM>, which may be used in this configuration to direct light from the light sources into the lumen, aimed at the workspace at the distal end of the cannula tube and toward target tissue. <FIG> also shows the control system <NUM>, which is configured and operable to operate the light sources, obtain video image data captured by the camera, and generate/translate corresponding video image data for display on the display screen <NUM>. The camera assembly and lighting assemblies may be supported and held proximally to the proximal end of the cannula tube on a mounting structure <NUM>, which in this embodiment comprises a ring of larger diameter than the cannula tube, fixed above the proximal end of the cannula tube.

<FIG> illustrate the construction of the lighting assemblies <NUM>. These lighting assemblies include the light source <NUM>, prism <NUM> and the lens <NUM> positioned between the lens and the prism. The light source is characterized by a beam axis 12B, and a broad beam angle α, which may the result of a un-lensed LED, or a packaged LED with a lens configured to focus light from the LED into the broad beam angle. The packaged LED is typically provided in a form that comprises a substrate, the light-emitting diode itself, and a lens covering the light-emitting diode. In the case of a white light LED, the packaged LED may also comprise a phosphor (to convert some blue light from the diode into red and green light, to produce a package that emits white light). A typical beam angle for a packaged LED may be in the range of <NUM>° to <NUM>°. When used in the cannula system of <FIG>, this wide beam angle would result in excessive glare which obscures images obtained with the camera assembly. To reduce this glare, the lens <NUM> is a focusing lens provided in the form of a convex lens or a gradient index lens (a GRIN lens) or a collimator lens, which functions to focus light from the packaged LED into a narrower beam angle. A suitable combination of packaged LED and lens is (<NUM>) a CREE® XQEAWT led and (<NUM>) an Edmunds #<NUM>-<NUM> GRIN lens available from Edmunds Optics. A GRIN lens is preferred due to its small cross-section (the cross-section perpendicular to its optical axis) for a given focusing power, which facilitates placement of the lighting assembly on the proximal end of the cannula tube. The prism is preferably a right angle prism, but different forms of prism may be used, to accommodate different angles between the optical axis (the long axis, in this example) <NUM> of the GRIN lens, output beam axis <NUM> and the central axis <NUM> of the cannula tube. The overall lighting assembly has an output beam axis which corresponds to a viewing axis of the prism and the output beam axis <NUM> is at an angle to the optical axis <NUM> of the focus lens (in the example shown in <FIG>). In the case of a right angle prism, the optical axis of the focusing lens may be perpendicular to the viewing axis of the prism. The distal-most optical surface of the lighting assembly, whether it be the distal face of the prism <NUM> or a distal surface of the focusing lens (where the focusing lens optical axis is directed toward the distal end of the cannula, used without a prism, as shown in <FIG>) is located at the proximal end of the cannula tube, and preferably disposed proximally of the proximal end of the cannula tube.

The lighting assembly may be configured with an air gap <NUM> between the packaged LED and the lens and an air <NUM> gap between the lens and the prism. With this combination using a CREE® XQEAWT led and an Edmunds #<NUM>-<NUM> GRIN lens the resultant beam angle β, centered on the lighting assembly beam axis 10B, is about <NUM>°.

<FIG> illustrate a lighting assembly without a prism, in which the optical axis (of the focusing lens) <NUM> is aligned with the length of the cannula tube <NUM>. Other features of this embodiment are similar to the features of <FIG>, including the cannula <NUM> and the cannula tube <NUM>, the camera assembly <NUM> and the prism <NUM>. The LED's are disposed with a beam axis 12B directed distally into the cannula lumen and toward the distal end of the cannula tube, with the lens <NUM> aligned with its optical axis <NUM> aligned with the LED beam axis and also pointed distally, toward the cannula lumen and the distal end of the cannula tube. In the configuration, the prism is not necessary. The overall lighting assembly in this embodiment has an output beam axis which corresponds to the optical axis of the focus lens, and this output beam axis is directed toward the distal end of the cannula tube.

In the top view of <FIG>, the positions of the light sources, and the corresponding lenses <NUM> and LED light sources <NUM>, along with the camera assembly <NUM> and the camera prism <NUM>, are shown, with the light sources and camera prism overhanging the lumen <NUM> of the cannula tube <NUM> to a limited extent, allowing for illumination and visualization of the workspace at the distal end of the cannula tube while also allowing for passage of tools into the workspace, through the cannula tube. <FIG> shows the relationship between the lighting assembly <NUM> with the light source <NUM> and its beam angle α transmitting light into a GRIN lens <NUM>, with the light leaving the GRIN lens with a narrow beam angle β along the lighting assembly beam axis <NUM>.

The output beam angle may be slightly larger or smaller, depending on the dimensions of the cannula. For a relatively short, wide cannula <NUM> long with a <NUM> inner diameter, for example, a narrow beam angle of about <NUM> to <NUM>°, more preferably about <NUM>°, will provide good illumination with reduced glare. For a <NUM> long cannula with a <NUM> inner diameter, a narrow beam angle of about <NUM> to <NUM>°, more preferably about <NUM>°, will provide good illumination with reduced glare. More generally, a configuration of light source and focusing lens providing an output beam angle of less than about <NUM>° may be used to provide good illumination with minimal glare.

The illustrations show a beam axis (the center of light leaving the lens) of the GRIN lens coincident with the optical axis of the GRIN lens, the beam axis may be altered by positioning the LED off-center relative to the longitudinal center of the GRIN lens (which typically is the optical axis). This will cause the output beam axis of the GRIN lens in Figured <NUM> and <NUM> to depart from parallel to the optical axis. Thus, placement of the LED, such that the beam axis of the LED is displaced from the optical axis of the GRIN lens will cause the output beam axis of the GRIN lens to be at an axis to the optical axis. The output beam axis may thus be aimed at the center of the distal opening of the cannula, to intersect a central axis (or other feature) of the cannula tube, while the lighting assembly output remains near the circumference of the cannula tube.

Claim 1:
A cannula system for accessing a surgical field, said cannula system comprising:
a cannula comprising a cannula tube (<NUM>) with a proximal end and a distal end and a lumen (<NUM>) extending from the proximal end to the distal end; and
a lighting assembly (<NUM>) secured to the proximal end of the cannula tube;
wherein said lighting assembly comprises a light source (<NUM>) and a focusing lens (<NUM>), said light source having a first beam axis and a first beam angle (α), said first beam axis aligned with an optical axis (<NUM>) of said focusing lens (<NUM>), said lighting assembly (<NUM>) having an output beam angle (β) and an output beam axis (<NUM>), wherein said output beam axis (<NUM>) is directed toward the distal end of the cannula tube (<NUM>), wherein
said output beam angle (β) is smaller than said first beam angle (α);
wherein the lumen (<NUM>) and lighting assembly (<NUM>) are configured to allow passage of surgical tools through the cannula while the lighting assembly (<NUM>) is disposed on the proximal end of the cannula tube (<NUM>);
whereby the lighting assembly (<NUM>) provides illumination for the surgical field with reduced glare within the cannula tube (<NUM>).