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Medical Lead System and Method for Insertion into the Spinal Cord

IP.com Disclosure Number: IPCOM000011389D
Publication Date: 2003-Feb-17
Document File: 4 page(s) / 49K

Publishing Venue

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Abstract

Medical lead systems with a number of improvements are disclosed. A lead introducer (epidural needle) with a slit along the length of the cannula allows implantation of non-isodiametric leads and/or connectors. Lead designs that include an offset may be used with the slit cannula. The introducer or stylet may be removed while monitoring stimulation. The introducer and lead may be rotated independently or as a unit, and the angle of rotation of the lead/introducer unit may be measured. Integral suture sleeve (lead anchor) designs include incorporation into the lead body and/or into the offset. The offset also facilitates use of a lead that has a through-hole at the distal tip. The various improvements result in more accurate lead placement, decreased implantation time, improved lead steerability and torqueability, increased lead reliability and stability, and decreased lead breakage, among other things.

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Medical Lead System and Method for Insertion into the Spinal Cord

Background

Implantation of Spinal Cord Stimulation (SCS) leads is typically performed using an epidural needle, a guidewire or obturator, and a stylet.� After placement of the stimulation lead at the desired target site, the epidural needle, guidewire or obturator, and stylet are removed.� Then a lead anchor (commonly referred to as a suture sleeve) is placed over the lead and used to anchor the lead to surrounding ligaments and/or fascia.

Epidural needles, more generally referred to as introducers, are tubular members.� The maximum diameter of a lead or catheter that is to be inserted though the introducer must be less than the inner diameter of the introducer.� Attempts to overcome this limitation have resulted in, among other things, the development of splitable cannulas.� US Patent No. 6,159,198 describes an introducer system with a splitter that is used to split the cannula after placement of a lead or catheter.� Splitable cannulas are typically manufactured of a non-metallic material(s) such as polyamides, polyesters, polyether block amides, polyurethanes, fluorinated ethylene-propylene (FEP), polytetrafluoroethylene (PTFE), silicone rubbers, and combinations of these.� However, these needles have sharp, burred edges after they are split.� These sharp edges can damage the device that is inserted through the needle.

Due to the constraints of a typical introducer system, as described above, the suture sleeve (a.k.a., lead anchor) must be a separate component that is placed on the lead after removal of the introducer.� Most commonly, the suture sleeve is a tubular member that is slid over the proximal end of the lead body.� The sleeve is then tied around the lead to limit movement along the axial direction of the lead.� Next, the sleeve is secured to the tissue to limit movement of the lead with respect to the implant location.� A common problem associated with this type of suture sleeve is lead damage.� This is caused when the suture is excessively tightened around the sleeve and lead body.� Other sleeve/lead designs allow the sleeve to move on the lead, resulting in lead migration.

Other challenges facing current lead and catheter designs include steerability, torquability, and stiffness.� These properties impact the ease of implantation, and thus the trauma and procedure time endured by the patient.� Improvements are needed in today’s introducers, leads, and suture sleeves to address the problems described above.

Detailed Description

The systems and methods of this invention allow for the use of non-isodiametric leads, and eliminate the need for a separate suture sleeve, in addition to providing other improvements in the areas described above.� The system includes a slit cannula, a non-isodiametric lead, and a built-in lead anchor.� As will be seen, the systems and methods herein provide improvements in the above areas and in the ability to monitor the efficacy of stimu...