How can I convert a mupad to a MATLAB function when using tex symbols?

I am using mupad for some symbolic calculations. Since I want to export to latex, I use tex-like symbols as variable names, e.g.

 `A_{segment}`(`ξ`) := r*int(`ξ`*`P_{LD}`,`ξ`=0..`ξ_{max}`)

Now I want to convert these to MATLAB functions for numeric evaluation. First problem is with getVar, what is the variable name I should use? Second problem, assuming I convert the above to

 A_S := r*int(`ξ`*`P_{LD}`,`ξ`=0..`ξ_{max}`)

so I can use

 A_segment = getVar(mphandle,'A_S')

I get something like

 A_segment = (`P_{LD}`*r*(r - x)^2)/2

That leads to the second problem, this symbolic term can't be converted to a MATLAB function:

 >> matlabFunction(A_segment)
 Error using sym/matlabFunction>checkVars (line 159)
 Variable names must be valid MATLAB variable names.

 Error in sym/matlabFunction (line 104)
 vars = checkVars(funvars,opts);