Sphenoid sinus stent

[0001] I. Field of the Invention

[0002] This invention relates generally to stents for maintaining a passageway in an animal body patent, and more particularly to a stent specifically designed for use in treating chronic sinusitis where the sphenoid sinus is involved.

[0003] II. Discussion of the Prior Art

[0004] The paranasal sinuses are air-filled pockets located within the bones of the face and around the nasal cavity. Each sinus is named for the bone in which it is located, e.g., maxillary, ethmoid, frontal and sphenoid.

[0005] Each of these air-filled pockets has an opening that connects to the nose. This opening is called an ostium.

[0006] The nose and sinuses are closely related. The nasal septum divides the nose into two nasal cavities. The sidewall of the nose (the lateral nasal wall) has three important structures, which are known as the superior, middle and inferior turbinates sometimes referred to as nasal concha. Each is a rounded projection that extends the length of the nasal cavity. The space between each turbinate is called a meatus. Each meatus is named for the turbinate above it.

[0007] The inferior turbinate, which is larger than the other turbinates, runs parallel to the floor of the nose. The nasal nasolacrimal duct drains tears into the inferior meatus.

[0008] The middle turbinate is located above the inferior turbinate. The anterior or front ethmoid cells open into the middle meatus. The frontal sinus drains into the middle meatus.

[0009] The superior turbinate, which is the smallest turbinate, is above the middle turbinate. The posterior ethmoid cells drain into the superior meatus. The space between the superior turbinate, the septum and the sphenoid sinus front wall is known as the sphenoethmoid recess. The sphenoid sinus drains into this recess.

[0010] The paranasal sinuses are covered with a special lining or epithelium. The lining secretes mucous, a complex substance that keeps the nose and sinuses moist. The sinus epithelium is ciliated; that is, each cell on its surface has a cilium, which is a relatively long structure that has the capacity to push sinus mucous. This movement of mucous called mucociliary clearance is not random, but rather it is programmed so that the mucous moves along in a specific pattern.

[0011] The mucous membranes lining the nasal cavity and the paranasal sinuses may become inflamed due to infections, such as the common cold or allergies. When inflamed, the blood vessel dilates, the membranes swell and the mucous secretions increase. The resulting congestion interferes with breathing and often causes a “runny nose”. The infection may spread into the mucous membranes of the paranasal sinuses, blocking their connection with the nasal cavity and causing them to fill with mucous. Since the sinuses act as resonance chambers, this changes the sound of the voice and may also cause such a pressure increase within the sinuses that severe headaches result.

[0012] Chronic sinusitis is arbitrary defined as rhinosinusitis of at least 12 consecutive weeks duration and persistence of one major and two minor signs and/or symptoms. Major signs and symptoms include fever, facial pain or pressure, nasal obstruction or nasal discharge with purulence and hyposmia. Cough, dental pain, headache and ear pain or ear fullness are considered minor signs and symptoms. The sphenoid sinus normally drains through its ostium into the space between the superior and middle turbinates. However, due to infection or possibly other causes, the membranes proximate the ostium may swell to the point where drainage ceases and fluid pressure builds up creating severe pain behind the eyes. In treating chronic sphenoid sinusitis, under endoscopic guidance, the ostium of the sphenoid sinus is surgically enlarged to facilitate drainage from the sphenoid sinus cavity. However, tissue swelling and surgical exudates at the surgical site may narrow or scar tissue may close the ostium. Thus a need exists for a means whereby the surgically created opening will remain patent for a period of time sufficient to treat the sinusitis condition.

[0013] In accordance with the present invention, there is provided a stent for placement in the surgically enlarged ostium of sphenoid sinus that comprises a soft, compressible, plastic tube of a predetermined diameter, the tube having a proximal end, a distal end and a lumen extending therebetween. The distal end of the tube terminates in a generally hemispherical, hollow dome whose diameter is greater than the predetermined diameter of the plastic tube. The stent of the present invention further includes an annular flange that extends radially outward from an exterior surface of the compressible plastic tube at a location between the proximal and distal ends of the plastic tube.

[0014] In use, the ostium of the sphenoid sinus is surgically enlarged using endoscopic visualization and the stent is then placed into the enlarged ostium. The stent may be placed using a straight Blakesly cup forceps and, in doing so, the hemispherical hollow dome is pinched, allowing it to be compressed for insert through the ostium so that the dome will reside within the sphenoid sinus. The flange or collar remains exterior to the sinus and abuts the bony wall through which the ostium extends. This prevents the stent from falling into the sinus. The hemispherical hollow dome prevents the stent from dislodging out of the sphenoid into the nasal cavity.

[0015] Using the lumen of the stent provides access to the sphenoid sinus for irrigating with antibiotics if necessary and suctioning. The surgeon may use the portion of the stent that projects out of the sphenoid sinus as the irrigation and aspiration port.

[0016] At a later time, the stent may be removed by again using a forceps to grasp the proximal end of the tube and pulling same in the anterior direction. This causes the front dome to compress on itself and easily pass back through the ostium.

[0022] Referring first to FIG. 1, there is shown a isometric view of a stent especially designed for placement in the ostium of the sphenoid sinus in the treatment of sphenoid sinusitis. It is indicated generally by numeral 10 and comprises a soft compressible plastic tube 12 of a predetermined outer diameter and having a proximal end 14, a distal end 16 and a lumen 18 extending therebetween. A distal end portion of the tube 12 is tapered and terminates in a integrally formed, generally hemispherical hollow dome 20 whose diameter is greater than the predetermined diameter of the plastic tube 12. The lumen 18 extends all the way through the surface of the dome 20.

[0023] A short predetermined distance proximal of the distal end 16 of the tube 12 is an integrally formed, radially extending flange 22, the diameter of which is generally equal to the diameter of the hemispherical dome 20. The stent is preferably formed in a molding operation from a suitable plastic. Without limitation, the plastic may be silicone rubber of a hardness in a range of from about 50 to 70 Shore A.

[0024] Referring to the cross-sectional view of FIG. 3 which is taken along the line 3—3 in FIG. 2, the dome 20 has a convex outer wall 24 and a concave inner wall 26. This facilitates the ability to compress the dome to a smaller diameter by pinching the outer periphery of the dome between the jaws of a suitable forceps.

[0025] In order to provide an enabling disclosure of a preferred embodiment, the following dimensions may apply to the stent. It should be understood, however, that the values provided are not to be considered as limitive of the invention since the stent device will remain workable with minor changes in the values provided.

[0026]

	Length	0.422	inch
	Outside Diameter	0.158	inch
	Inside Diameter	0.108	inch
	Diameter of Flange 22	0.315	inch
	Diameter of Dome 20	0.311	inch
	Radius of Dome	0.164	inch
	Gap Between Dome & Flange	0.079	inch
	Flange Thickness	0.028	inch
	Angle of Taper	6°

[0027] Referring next to FIG. 4, it is an anatomical sagital view showing the sphenoid sinus 28 with the stent 10 of the present invention inserted through a surgically enlarged ostium, such that the hemispherical head portion 20 resides in the sphenoid sinus 28 while the flange 22 and the proximal portion of the tubular body 12 resides in the sphenoethmoid recess 29 above the superior nasal concha 30. For reference purposes, the middle nasal concha is identified by numeral 32 and the inferior nasal concha by numeral 34 in the view of FIG. 4.

[0028] It can be seen that the flange 22 on the stent 10 is of a diameter larger than the surgically enlarged ostium in which the stent 10 is placed. This flange prevents the stent from falling into the sphenoid sinus cavity 28.

[0029] As previously indicated, because of the inclusion of the lumen in the stent 10, a surgeon may inject fluids through the lumen into the sphenoid sinus or, alternatively, he/she may suction out the contents of the sinus by coupling a suitable length of tubing from the proximal end of the stent where the tubing then extends out through the external nares 36 of the patient's nose to a source of irrigation fluid or a vacuum.

[0030] This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself