Per poco non mi sono venute le vertigini.

Per poco means almost, nearly, or for a moment I was on the verge of...

In this sentence, it introduces a near-miss idea:

• Per poco non... = I almost...

So Per poco non mi sono venute le vertigini means something like:

• I almost got dizzy
• I nearly got vertigo

It is a very common expression in Italian.

This is one of the most confusing parts for English speakers.

In Italian, after per poco, you often get:

• Per poco non cadevo = I almost fell
• Per poco non morivo = I almost died

So the non is standard in this pattern, even though the overall meaning is almost happened, not didn't happen in the ordinary negative sense.

A useful way to remember it is:

• per poco non + verb = came very close to happening

In modern usage, some speakers may sometimes omit non, but per poco non is very common and standard.

Literally, it means they came to me.

Here:

• mi = to me
• sono venute = came / have come (feminine plural)

So the structure is literally something like:

• To me came the dizziness

That sounds unnatural in English, but Italian often uses venire (to come) for bodily sensations or states:

• Mi è venuta fame = I got hungry / literally Hunger came to me
• Mi è venuto un dubbio = A doubt occurred to me
• Mi sono venute le vertigini = I got dizzy / literally The vertigo came to me

Because the verb agrees with le vertigini, which is treated as feminine plural.

Breakdown:

• venire in the passato prossimo with essere must agree with the subject
• the subject here is le vertigini
• vertigini is grammatically plural
• so the past participle becomes venute = feminine plural

Compare:

• Mi è venuta fame → fame is feminine singular
• Mi è venuto un capogiro → un capogiro is masculine singular
• Mi sono venute le vertigini → le vertigini is feminine plural

In Italian, vertigini is normally used in the plural.

So even when English says dizziness or vertigo as if it were singular, Italian usually says:

• le vertigini

That is why you get:

• le vertigini
• sono venute
• venute in the plural

This is just something to learn as a vocabulary item: vertigini behaves like a plural noun in normal usage.

Mi is an object pronoun meaning to me.

So:

• mi sono venute le vertigini

literally means:

• the dizziness came to me

In more natural English:

• I felt dizzy
• I got dizzy
• I nearly got dizzy

Italian often uses this kind of structure for physical sensations and internal states.

Other examples:

• Mi è venuta sonnolenza = I became sleepy
• Mi è venuta fame = I got hungry
• Mi è venuto mal di testa = I got a headache

Because the verb here is venire, and in compound tenses venire takes essere, not avere.

So in the passato prossimo:

• sono venuto / venuta
• sei venuto / venuta
• è venuto / venuta
• siamo venuti / venute
• sono venuti / venute

Here the subject is le vertigini, so:

• le vertigini sono venute

And with the pronoun:

• mi sono venute le vertigini

The order is normal for Italian with clitic pronouns.

The pronoun mi comes before the auxiliary:

• mi sono venute le vertigini

This is the standard placement in a finite verb form.

Compare:

• mi è venuta fame
• ti è venuto sonno
• gli è venuto un dubbio

You could sometimes rearrange parts for emphasis, but the neutral order is exactly the one in the sentence.

Grammatically, it is in the passato prossimo:

• sono venute

Depending on context, English might translate it as:

• I almost got dizzy
• I almost became dizzy
• I nearly felt faint
• I almost had a dizzy spell

In many cases, English does not need to mirror the tense mechanically. What matters is that Italian is using a completed past event or near-event.

Yes, but it would not feel exactly the same.

• Per poco non mi sono venute le vertigini refers to a specific near-event in the past.
• Per poco mi venivano le vertigini sounds more like I was just about to get dizzy or I nearly started feeling dizzy, with a more ongoing or immediate feel.

Also, with per poco, many speakers strongly prefer the version with non, especially in the most standard pattern:

• Per poco non mi sono venute le vertigini

So for a learner, the original sentence is the safest model to remember.

There are alternatives, depending on nuance.

For example:

• Per poco non mi girava la testa = I almost felt my head spinning
• Per poco non svenivo = I almost fainted
• Mi è venuto un capogiro = I got dizzy / I had a dizzy spell

But mi sono venute le vertigini is a very natural and common way to express dizziness or vertigo, especially when the feeling is strong or sudden.

It is basically neutral standard Italian.

It works in everyday speech and in writing.
It is not especially formal, but it is not slang either.

So it is a very useful sentence pattern to learn:

• Per poco non + verb
• mi è venuto / mi sono venute + physical sensation

Both are common and natural in standard Italian.