Weakness or sensory loss is an abrupt change of neurological status. A wrist drop is a condition where a person cannot extend their wrist and it just hangs there, flaccid, limp. They are usually not able to move out of that position due to the nerves, tendons and/or muscles not doing what their supposed to do. A better understanding of the condition always helps. It may not have been an acute symptom that made the patient have to run to the hospital, but it was sudden or unexpected from the normal way of life to get them to the doctor within 30 days. For example, a stab wound to the chest at or below the clavicle may damage the posterior cord which can cause wrist drop (acute). Another example, wrist drop has also been associated with lead poisoning due to the effect of lead on the radial nerve (sudden or gradual effect).
Remember also, the doctor's schedule may have been booked out for some time, patient may not have had a ride, etc...all things to consider.
I'm no doctor, but if I audited this note, his MDM would for sure rank High. I hope that helps you!