Do we potentially have a medical malpractice and medical neglect lawsuit?

The short delay between the visit to the Nurse Practitioner and the return to the hospital and the diagnosis of the ATRT suggests that any case against the nurse will fail on proximate cause. In other words, your child's underlying problem (the tumor) is what is causing her problems, not the delay in diagnosis. Having said that, no nurse practitioner is qualified to diagnose a complex neurological problem like cerebral palsy or a brain tumor, so you should definitely file a complaint against the practice.  If you want to investigate a case further, you should contact a local medical malpractice attorney (one in your state).  They take these cases on a contingency basis which means you only have to pay if you succeed.  Additionally, initial consultations are usually free. Below are some articles you may find helpful.  They are written for a New Jersey audience (where I practice) but the ideas discussed in these articles usually apply in most other jurisdictions as well.   Click here for an article that discusses the three main questions I ask when deciding whether to investigate a potential medical malpractice case. This discusses the issue of financial viability.   Click here for an article that explains what you can and should expect when pursuing a medical malpractice case.   Click here for more information about me.   Please understand that by answering your question in this informal forum I am not acting as your attorney. I am not doing anything to protect any legal rights that you have.  Medical malpractice cases need to be thoroughly investigated and to know whether you have a viable case, an attorney usually has to obtain and review all of the pertinent medical records and consult an expert.