DataSource Controls :: Use Is Null In Query Without Using Parameters For It Or Should Use Parameters For This Field Where Value Is NULL

here is my code for selectiong some records from db table

string strSql = "select * from mtblNBD where SentTo=@SentTo and InternalStatus Is NULL order by DeadLine desc";
SqlCommand com = new SqlCommand(strSql, con);
com.Parameters.Add("@SentTo", SqlDbType.NVarChar, 50).Value = (string)Session["uname"];

here I am using parameters for SenTo field but not for NULL so it is ok... or should I use parameters for this field where value is NULL , if yes then how can I use parameter for this