Here you go:

$updaters = array();

for ($i = 1; $i <= 10; $i++)
{
    if (isset($_POST[ permsA_ .$i]))
        $updaters[] =  ` .$i. ` =   .mysqli_real_escape_string($db, $_POST[ permsA_ .$i]).   ;
}

$insert = mysqli_query($db, UPDATE `tbl_perms` SET  .implode( , , $updaters).
     WHERE `userid` =  .$id)or die(mysqli_error($db));

foreach ($_POST as $key=>$value) {
  if (preg_match( /^permsA/ ,$key)) {
    list($tmp,$num)=explode( _ ,$key);
    $perms[]="`$num` = " . (int)$value; //or some other method of sanitizing the $value
  }
}

$sql="UPDATE tbl_perms SET " . implode( , $perms) . "WHERE userid =  $id " ;

What the others said, except if possible I d do it a bit differently - rather than having to use a $i to control the loop, I d rename the form so that the fields were called something like:

<input type="checkbox" value="1" name="permsA[1]">
<input type="checkbox" value="1" name="permsA[2]">

etc etc.

You d then get a post array you could reference like this like this:

$_POST[ permsA ][1];
$_POST[ permsA ][2];

Advantage of this is that you can do:

$bits = array();
foreach ($_POST[ permsA ] as $key=>$value) {
  $bits[] = $key . " =  " . mysqli_real_escape_string($db, $value) . " ";
}

$sql = "UPDATE permissions SET " . implode( ,  , $bits) . " WHERE userid =  $id  ") 
 or die(mysqli_error($db));

And the advantage of doing that is that you won t one day get a random bug when you add more permissions to the system and go past the max you are using for $1 :)

Appreciate you may not be able to change the form though, or may not ever add more permissions, in which case this solution is no better.

Just a draft:

$sql = "UPDATE `tbl_perms` SET ";
for ($i = 1; $i < 100; i++) {
  if (isset($_POST[ permsA_  . $i])) {
    if ($i > 1) $sql .= ",";
    $sql .= "`$i` = " . mysqli_real_escape_string($db,$_POST[ permsA_1 ]) . " ";
  }
}
$sql .= " WHERE `userid` =  $id ";

Please note that the 100 is just an arbitrary number