Tissue discrimination and applications in medical procedures

• US 20020072686A1
• Filed: 05/18/2001
• Published: 06/13/2002
• Est. Priority Date: 05/18/2000
• Status: Active Grant

• Current Assignee: Nuvasive Incorporated
• Original Assignee: Nuvasive Incorporated
• Inventors: Foley, Kevin, Hoey, Michael, Stone, Corbett W.
• Granted Patent: US 6,760,616 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 17/7001 Screws or hooks combined with longitudinal elements which do not contact vertebrae A61B17/7058 takes precedence
• CPC Class Codes: A61B 18/02 by cooling, e.g. cryogenic techniques devices for cooling specific reflex points of the body within cell-life limits A61H39/06
• CPC Class Codes: A61B 18/04 by heating by applying electromagnetic radiation A61B18/18; hyperthermia using electric or magnetic fields, radiation or ultrasound A61N
• CPC Class Codes: A61B 2017/00022 Sensing or detecting at the treatment site
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4869 Determining body composition
• CPC Class Codes: A61B 5/4893 Nerves

Abstract

A method and system for discriminating tissue types, controlling the level of therapy to tissue, and determining the health of a known tissue by measuring the characteristics an electrical signal applied to conductive element located within or by the tissue. Additionally, the method and system may be used for determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue, whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue, and whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue.

Claims

1. A method of discriminating between tissue types comprising the steps of:

a) placing a probe having a conductive element within a tissue;

b) applying a signal to the conductive element;

c) determining characteristics of the applied signal; and

d) determining the tissue type based on the determined characteristics.

2. The method of claim 1, wherein step b) applies signals having a range of predetermined frequencies to the conductive element.

3. The method of claim 2, wherein the step d) includes determining the tissue type based on the determined characteristics and frequency of the applied signal.

4. The method of claim 1, wherein the conductive element is an electrode.

5. The method of claim 4, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

6. The method of claim 1, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

7. The method of claim 1, wherein the probe comprises any surgical tool.

8. The method of claim 1, wherein the signal is one of an electrical and optical signal.

9. The method of claim 1, wherein further comprising the step of advancing the probe from a first tissue type into a second tissue type where the first tissue type is know and wherein step d) includes determining the second tissue type based on the determined characteristics and the first tissue type.

10. The method of claim 1, wherein the signal is an electrical signal having a sliding frequency.

11. The method of claim 1, wherein the signal is a sinusoidal electrical signal.

12. The method of claim 1, wherein measured characteristics of the signal include a phase angle.

13. The method of claim 1, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

15. The article of manufacture of claim 14, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

16. The article of manufacture of claim 15, wherein the step c) includes determining the tissue type based on the determined characteristics and frequency of the applied signal.

17. The article of manufacture of claim 14, wherein the conductive element is an electrode.

18. The article of manufacture of claim 14, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

19. The article of manufacture of claim 14, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

20. The article of manufacture of claim 14, wherein the probe comprises any surgical tool.

21. The article of manufacture of claim 14, wherein the signal is one of an electrical and optical signal.

22. The article of manufacture of claim 14, wherein the signal is an electrical signal.

23. The article of manufacture of claim 14, wherein the signal is an electrical signal having a sliding frequency.

24. The article of manufacture of claim 14, wherein the signal is a sinusoidal electrical signal.

25. The article of manufacture of claim 14, wherein measured characteristics of the signal include a phase angle.

26. The article of manufacture of claim 14, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

28. The apparatus of claim 27, wherein means for applying a signal includes means for applying signals having a range of predetermined frequencies to the conductive element.

29. The apparatus of claim 28, wherein the means for determining the tissue type includes means for determining the tissue type based on the determined characteristics and frequency of the applied signal.

30. The apparatus of claim 27, wherein the conductive element is an electrode.

31. The apparatus of claim 27, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

32. The apparatus of claim 27, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

33. The apparatus of claim 27, wherein the probe comprises any surgical tool.

34. The apparatus of claim 27, wherein the signal is one of an electrical and optical signal.

35. The apparatus of claim 27, wherein the signal is an electrical signal.

36. The apparatus of claim 27, wherein the signal is an electrical signal having a sliding frequency.

37. The apparatus of claim 27, wherein the signal is a sinusoidal electrical signal.

38. The apparatus of claim 27, wherein measured characteristics of the signal include a phase angle.

39. The apparatus of claim 27, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

97. The method of claim 1, wherein the probe includes a pair of electrodes and the signal passed between said electrodes.

98. The method of claim 1, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

99. The method of claim 1, wherein the probe comprises any surgical tool.

100. The method of claim 1, wherein the signal is one of an electrical and optical signal.

101. The method of claim 1, wherein the signal is an electrical signal.

102. The method of claim 1, wherein the signal is an electrical signal having a sliding frequency.

103. The method of claim 1, wherein the signal is a sinusoidal electrical signal.

104. The method of claim 1, wherein measured characteristics of the signal include a phase angle.

105. The method of claim 1, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

14. An article of manufacture for use in discriminating between tissue types where a probe having conductive element is placed within a tissue whose type is to be discriminated, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps:

a) applying a signal to the conductive element;

b) determining characteristics of the applied signal; and

c) determining the tissue type based on the determined characteristics.

27. An apparatus for use in discriminating between tissue types where a probe having conductive element is placed within a tissue whose type is to be discriminated, the apparatus including:

a) means for applying a signal to the conductive element;

b) means for determining characteristics of the applied signal; and

c) mean s for determining the tissue type based on the determined characteristics.

40. A method of applying therapy to tissue comprising the steps of:

a) placing a probe with a conductive element within the tissue;

b) applying therapy to the tissue;

c) applying a signal to the conductive element;

d) determining characteristics of the applied signal; and

e) determining the level of therapy applied to the tissue based on the determined characteristics; and

f) stopping the application of therapy based on the determined level of therapy applied to the tissue.

41. The method of claim 40, wherein step b) applies signals having a range of predetermined frequencies to the conductive element.

42. The method of claim 41, wherein the step d) includes determining the level of therapy applied to the tissue based on the determined characteristics and frequency of the applied signal.

43. The method of claim 40, wherein the conductive element is an electrode.

44. The method of claim 43, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

45. The method of claim 40, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

46. The method of claim 40, wherein the probe comprises any surgical tool.

47. The method of claim 40, wherein the signal is an electrical signal having a sliding frequency.

48. The method of claim 40, wherein measured characteristics of the signal include a phase angle.

49. The method of claim 48, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

50. An article of manufacture for use in applying therapy to tissue where a probe having conductive element is placed within the tissue, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps:

a) applying a signal to the conductive element;

b) determining characteristics of the applied signal; and

c) determining the level of therapy applied to the tissue based on the determined characteristics; and

d) stopping the application of therapy based on the determined level of therapy applied to the tissue.

51. The article of manufacture of claim 50, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

52. The article of manufacture of claim 51, wherein the step c) includes determining the level of therapy applied to the tissue based on the determined characteristics and frequency of the applied signal.

53. The article of manufacture of claim 50, wherein the conductive element is an electrode.

54. The article of manufacture of claim 50, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

55. The article of manufacture of claim 50, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

56. The article of manufacture of claim 50, wherein the signal is one of an electrical and optical signal.

57. The article of manufacture of claim 50, wherein the signal is an electrical signal having a sliding frequency.

58. The article of manufacture of claim 50, wherein measured characteristics of the signal include a phase angle.

59. The article of manufacture of claim 58, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

60. An apparatus for use in applying therapy to tissue where a probe having conductive element is placed within the tissue, the apparatus including:

a) means for applying a signal to the conductive element;

b) means for determining characteristics of the applied signal; and

c) means for determining the level of therapy applied to the tissue based on the determined characteristics; and

d) means for stopping the application of therapy based on the determined level of therapy applied to the tissue.

61. The apparatus of claim 60, wherein means for applying a signal includes means for applying signals having a range of predetermined frequencies to the conductive element.

62. The apparatus of claim 61, wherein the means for determining the level of therapy applied to the tissue includes means for determining the level of therapy applied to the tissue based on the determined characteristics and frequency of the applied signal.

63. The apparatus of claim 60, wherein the conductive element is an electrode.

64. The apparatus of claim 60, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

65. The apparatus of claim 60, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

66. The apparatus of claim 60, wherein the signal is an electrical signal having a sliding frequency.

67. The apparatus of claim 66, wherein measured characteristics of the signal include a phase angle.

68. The apparatus of claim 67, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

70. The method of claim 69, wherein step b) applies signals having a range of predetermined frequencies to the conductive element.

71. The method of claim 70, wherein the step d) includes determining the tissue'"'"'s health based on the determined characteristics and frequency of the applied signal.

72. The method of claim 69, wherein the conductive element is an electrode.

73. The method of claim 72, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

74. The method of claim 69, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

75. The method of claim 69, wherein the signal is an electrical signal having a sliding frequency.

76. The method of claim 75, wherein measured characteristics of the signal include a phase angle.

77. The method of claim 76, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

79. The article of manufacture of claim 78, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

80. The article of manufacture of claim 79, wherein the step c) includes determining the tissue'"'"'s health based on the determined characteristics and frequency of the applied signal.

81. The article of manufacture of claim 78, wherein the conductive element is an electrode.

82. The article of manufacture of claim 81, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

83. The article of manufacture of claim 82, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

84. The article of manufacture of claim 82, wherein the signal is an electrical signal having a sliding frequency.

85. The article of manufacture of claim 84, wherein measured characteristics of the signal include a phase angle.

86. The article of manufacture of claim 85, wherein measured characteristics of the signal further include an impedance of the signal through the tissue.

88. The apparatus of claim 67, wherein means for applying a signal includes means for applying signals having a range of predetermined frequencies to the conductive element.

89. The apparatus of claim 88, wherein the means for determining the tissue'"'"'s health includes means for determining the tissue'"'"'s health based on the determined characteristics and frequency of the applied signal.

90. The apparatus of claim 89, wherein the conductive element is an electrode.

91. The apparatus of claim 90, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

92. The apparatus of claim 90, wherein the probe comprises one of an elongated member, a cannula, a tissue ablation device, and a needle.

93. The apparatus of claim 91, wherein the signal is an electrical signal having a sliding frequency.

94. The apparatus of claim 93, wherein measured characteristics of the signal include a phase angle.

95. The apparatus of claim 94, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

69. A method of determining a known tissue'"'"'s health comprising the steps of:

a) placing a probe having a conductive element within the tissue;

b) applying a signal to the conductive element;

c) determining characteristics of the applied signal; and

d) determining the tissue'"'"'s health based on the determined characteristics.

78. An article of manufacture for use in determining a known tissue'"'"'s health where a probe having conductive element is placed within the tissue, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps:

a) applying a signal to the conductive element;

b) determining characteristics of the applied signal; and

c) determining the tissue'"'"'s health based on the determined characteristics.

87. An apparatus for use in determining a known tissue'"'"'s health where a probe having conductive element is placed within the tissue, the apparatus including:

a) means for applying a signal to the conductive element;

b) means for determining characteristics of the applied signal; and

c) means for determining the tissue type based on the determined characteristics.

96. A method for discriminating between various tissue types, comprising:

a) advancing a probe through a body of tissue, the probe having an electrode disposed thereon;

b) emitting a signal from the electrode on the probe such that the signal passes through tissue disposed near or adjacent to the electrode;

c) measuring characteristics of the signal; and

d) discriminating the tissue type based on the measured signal characteristics.

106. A method of determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue comprising the steps of:

a) applying a signal to the conductive tip;

b) determining characteristics of the applied signal; and

c) determining whether the conductive tip of the probe is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue based on the determined characteristics.

107. The method of claim 106, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

108. The method of claim 107, wherein the step c) includes determining whether the conductive tip of the probe is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue based on the determined characteristics and frequency of the applied signal.

109. The method of claim 107, wherein the conductive element is an electrode.

110. The method of claim 109, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

111. The method of claim 109, wherein the signal is an electrical signal having a sliding frequency.

112. The method of claim 111, wherein measured characteristics of the signal include a phase angle.

113. The method of claim 112, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

115. The article of manufacture of claim 114, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

116. The article of manufacture of claim 115, wherein the step c) includes determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue based on the determined characteristics and frequency of the applied signal.

117. The article of manufacture of claim 116, wherein the conductive element is an electrode.

118. The article of manufacture of claim 117, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

119. The article of manufacture of claim 118, wherein the signal is an electrical signal having a sliding frequency.

120. The article of manufacture of claim 119, wherein measured characteristics of the signal include a phase angle.

121. The article of manufacture of claim 120, wherein measured characteristics of the signal further include an impedance of the signal through the tissue.

123. The apparatus of claim 122, wherein means for applying a signal includes means for applying signals having a range of predetermined frequencies to the conductive element.

124. The apparatus of claim 123, wherein the means for determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue includes means for determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue based on the determined characteristics and frequency of the applied signal.

125. The apparatus of claim 124, wherein the conductive element is an electrode.

126. The apparatus of claim 125, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

127. The apparatus of claim 126, wherein the signal is an electrical signal having a sliding frequency.

128. The apparatus of claim 127, wherein measured characteristics of the signal include a phase angle.

129. The apparatus of claim 128, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

131. The method of claim 130, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

132. The method of claim 131, wherein the step c) includes determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue based on the determined characteristics and frequency of the applied signal.

133. The method of claim 132, wherein the conductive element is an electrode.

134. The method of claim 133, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

135. The method of claim 134, wherein the signal is an electrical signal having a sliding frequency.

136. The method of claim 135, wherein measured characteristics of the signal include a phase angle.

137. The method of claim 136, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

139. The article of manufacture of claim 138, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

140. The article of manufacture of claim 139, wherein the step c) includes determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue based on the determined characteristics and frequency of the applied signal.

141. The article of manufacture of claim 140, wherein the conductive element is an electrode.

142. The article of manufacture of claim 141, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

143. The article of manufacture of claim 142, wherein the signal is an electrical signal having a sliding frequency.

144. The article of manufacture of claim 143, wherein measured characteristics of the signal include a phase angle.

145. The article of manufacture of claim 144, wherein measured characteristics of the signal further include an impedance of the signal through the tissue.

147. The apparatus of claim 146, wherein means for applying a signal includes means for applying signals having a range of predetermined frequencies to the conductive element.

148. The apparatus of claim 147, wherein the means for determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue includes means for determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue based on the determined characteristics and frequency of the applied signal.

149. The apparatus of claim 148, wherein the conductive element is an electrode.

150. The apparatus of claim 149, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

151. The apparatus of claim 150, wherein the signal is an electrical signal having a sliding frequency.

152. The apparatus of claim 151, wherein measured characteristics of the signal include a phase angle.

153. The apparatus of claim 152, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

155. The method of claim 154, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

156. The method of claim 155, wherein the step c) includes determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue based on the determined characteristics and frequency of the applied signal.

157. The method of claim 156, wherein the conductive element is an electrode.

158. The method of claim 157, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

160. The method of claim 159, wherein measured characteristics of the signal include a phase angle.

161. The method of claim 160, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

163. The article of manufacture of claim 162, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

164. The article of manufacture of claim 163, wherein the step c) includes determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue based on the determined characteristics and frequency of the applied signal.

165. The article of manufacture of claim 164, wherein the conductive element is an electrode.

166. The article of manufacture of claim 165, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

167. The article of manufacture of claim 166, wherein the signal is an electrical signal having a sliding frequency.

168. The article of manufacture of claim 167, wherein measured characteristics of the signal include a phase angle.

169. The article of manufacture of claim 168, wherein measured characteristics of the signal further include an impedance of the signal through the tissue.

171. The apparatus of claim 170, wherein means for applying a signal includes means for applying signals having a range of predetermined frequencies to the conductive element.

172. The apparatus of claim 171, wherein the means for determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue includes means for determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue based on the determined characteristics and frequency of the applied signal.

173. The apparatus of claim 172, wherein the conductive element is an electrode.

174. The apparatus of claim 173, wherein the probe includes a pair of electrodes and the signal is passed between said electrodes.

175. The apparatus of claim 174, wherein the signal is an electrical signal having a sliding frequency.

176. The apparatus of claim 175, wherein measured characteristics of the signal include a phase angle.

177. The apparatus of claim 176, wherein measured characteristics of the signal include an impedance of the signal through the tissue.

114. An article of manufacture for use in determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps:

a) applying a signal to the conductive tip;

b) determining characteristics of the applied signal; and

c) determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue based on the determined characteristics.

122. An apparatus for use in determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue, the apparatus including:

a) means for applying a signal to the conductive tip;

b) means for determining characteristics of the applied signal; and

c) means for determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue based on the determined characteristics.

130. A method of determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue comprising the steps of:

a) applying a signal to the conductive tip;

b) determining characteristics of the applied signal; and

c) determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue based on the determined characteristics.

138. An article of manufacture for use in determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps:

a) applying a signal to the conductive tip;

b) determining characteristics of the applied signal; and

c) determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue based on the determined characteristics.

146. An apparatus for use in determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue, the apparatus including:

a) means for applying a signal to the conductive tip;

b) means for determining characteristics of the applied signal; and

c) means for determining whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue based on the determined characteristics.

154. A method of determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue comprising the steps of:

a) applying a signal to the conductive tip;

b) determining characteristics of the applied signal; and

c) determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue based on the determined characteristics.

159. The method of clain 158, wherein the signal is an electrical signal having a sliding frequency.

162. An article of manufacture for use in determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps:

a) applying a signal to the conductive tip;

b) determining characteristics of the applied signal; and

c) determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue based on the determined characteristics.

170. An apparatus for use in determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue, the apparatus including:

a) means for applying a signal to the conductive tip;

b) means for determining characteristics of the applied signal; and

c) means for determining whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue based on the determined characteristics.