SOAP stands for "Subjective Objective Assessment Plan". This is a protocol for writing up a patient case, and getting all the pertinent information recorded in a single document. The Subjective information is information you observe directly from interacting with the patient, and what you garner from what the patient and/or the patient's family tells you. The Objective information is the patient's test results and other measurable data. The Assessment is the diagnosis of the patient. The Plan is the treatment plan.
There's an excellent slide show that will walk you through how to write a SOAP at this link. There are a variety of formats for SOAP notes; here is an example of a simple one, and this link has good suggestions for helping to organize your SOAP information.
For information about hydrocephalus, look here and here.