Meaning of a conjugation of 巡らす (巡らせ)


This is from a light novel I'm reading. Here's the part that I'm having
trouble with this sentence:

> オレは痛みを訴える頭を巡らせ

Based on what I know regarding the rest of the sentence, I believe that this
translation should be something like:

> I developed a headache as I thought it over.

According to my electronic dictionary, 巡らせ should be the imperative form of
巡らす. But I'm having trouble reasoning out why the imperative would be needed
here since he's thinking it over himself and not being commanded by someone
else to think it over.

If you need more context, here's the passage that I'm looking at:

> どうして、こんな事になったのだろう……。
>
> オレは痛みを訴える頭を巡らせ、こうなってしまった原因を思い返した。




> 「オレは[痛]{いた}みを[訴]{うった}える[頭]{あたま}を[巡]{めぐ}らせ」

「巡らせ」 is **not** in the imperative form. Rather, it is the [連用形]{れんようけい}
(continuative form) of the causative verb 「巡らせる」.

「頭を巡らせる」 is a set phrase meaning "to ponder".

> "I pondered in my aching head, trying to recall the cause as to why this had
> to happen."




> 「オレは[痛]{いた}みを[訴]{うった}える[頭]{あたま}を[巡]{めぐ}らせ」

「巡らせ」 is **not** in the imperative form. Rather, it is the [連用形]{れんようけい}
(continuative form) of the causative verb 「巡らせる」.

「頭を巡らせる」 is a set phrase meaning "to ponder".

> "I pondered in my aching head, trying to recall the cause as to why this had
> to happen."

