Real Time CSF Flow Measurement System & Method

Abstract

A system for measuring quantitative CSF flow in shunt tubing implanted under the skin. The system includes an array of thermo-sensors clustered in three sections, cooling device, placed on the skin surface and an associated data acquisition and analysis device. Two sensor sections are placed over the shunt on the skin and measure real time temperature responses related to CSF movement. One array placed adjacent the cooling device collects data on thermal properties of skin including skin thermal conductivity, specific heat, diffusivity, perfusion, and thermal inertia. The method involves assessing thermal properties of skin and measuring CSF flow in shunt tubing. The method is useful for shunt patency assessment, CSF valve adjustment procedures and CSF flow measurements related to CSF over drainage. Alternatively, only one section of sensors need be used when determining relative CSF flow, without the need to determine thermal skin properties and by applying the cooling device continuously.

What is claimed is: 
     
         1 . An apparatus for determining cerebrospinal fluid (CSF) flow rate in an implanted CSF shunt, said apparatus comprising:
 a pad that is configured to be placed against the skin of a patient over the location of the CSF shunt, said pad comprising:
 a first plurality of temperature sensors that are configured to be aligned in a transverse direction with respect to said CSF shunt and wherein one of said first plurality of temperature sensors is configured to be aligned with the CSF shunt; and 
 at least one temperature sensor associated with a temperature source that is positioned over the CSF shunt whenever said pad is placed against the skin and wherein said temperature source is applied continuously against the skin; and 
   a sensor processing device that is electrically coupled to said pad for receiving temperature data from each of said temperature sensors during said continuous application of said temperature source, and for determining a flow rate of said CSF through said CSF shunt from said temperature data.   
     
     
         2 . The apparatus of  claim 1  wherein said sensor processing device controls the activation of said temperature source. 
     
     
         3 . The apparatus of  claim 1  wherein said temperature source is a Peltier device. 
     
     
         4 . The apparatus of  claim 3  wherein said Peltier device maintains a temperature that differs from a skin temperature. 
     
     
         5 . The apparatus of  claim 4  wherein said temperature differs from said skin temperature by approximately 7°-14° C. 
     
     
         6 . The apparatus of  claim 3  wherein said continuous application of said temperature source is at least 5 minutes. 
     
     
         7 . The apparatus of  claim 1  further comprising a second plurality of temperature sensors that are configured to be aligned in a transverse direction with respect to said CSF shunt, downstream of said first plurality of temperature sensors, and wherein one of said second plurality of temperature sensors is configured to be aligned with the CSF shunt. 
     
     
         8 . The apparatus of  claim 1  wherein said at least one temperature sensor associated with a temperature source comprises a temperature sensor that is positioned on said temperature source or is configured to be positioned between said temperature source and the skin surface. 
     
     
         9 . The apparatus of  claim 7  wherein said at least one temperature sensor associated with a temperature source further comprises at least one other temperature sensor disposed adjacent said temperature source. 
     
     
         10 . A method for determining cerebrospinal fluid (CSF) flow rate in an implanted CSF shunt, said method comprising:
 applying a first plurality of temperature sensors against the skin over the location of the CSF shunt and wherein only one of said first plurality of temperature sensors is aligned with the CSF shunt;   associating at least one temperature sensor with a temperature source;   activating said temperature source against the skin continuously and aligned with the CSF shunt, said activating said temperature source comprises applying a temperature to the skin continuously that is different from a skin temperature;   collecting temperature data from said temperature sensors during said continuous activation of said temperature source; and   determining a flow rate of the CSF through the CSF shunt from said temperature data.   
     
     
         11 . The method of  claim 10  wherein said temperature source is a Peltier device. 
     
     
         12 . The method of  claim 11  wherein said Peltier device maintains a temperature that differs from a skin temperature. 
     
     
         13 . The method of  claim 12  wherein said temperature differs from said skin temperature by approximately 7°-14° C. 
     
     
         14 . The method of  claim 10  wherein said continuous activation of said temperature source is at least 5 minutes. 
     
     
         15 . The method of  claim 10  wherein said step of applying a first plurality of temperature sensors comprises applying a second plurality of temperature sensors against the skin over the location of the CSF shunt, downstream of said first plurality of temperature sensors, and wherein only one of said second plurality of temperature sensors is aligned with the CSF shunt. 
     
     
         16 . The method of  claim 10  wherein said step of associating at least one temperature sensor with a temperature source comprises positioning a temperature sensor on said temperature source or positioning said temperature sensor between said temperature source and the skin surface. 
     
     
         17 . The method of  claim 16  wherein said step of positioning a temperature sensor on said temperature or positioning said temperature sensor between said temperature sensor and the skin surface further comprises positioning at least one other temperature sensor adjacent said temperature source.