PHP Regex:删除span.class中括号内的文本

I have something like:

<span class="product-title">title (description)</span>

and I want to remove with PHP the parentheses and its content of all span.product-title, to be like this:

<span class="product-title">title</span>

I successfully removed the text and the parentheses(/\s\([^)]+\)/), but I want to match only the content within span.product-title.
How can I do this?
Thanks in advance. :)

All valid (and preferable) suggestions. However if you're simply looking for a quick & dirty regex fix, this should do:

/(<span class="product-title">.+?)\s*(?=\().+?\)(<\/span>)/i

replacing match with groups $1, $2 & $4.