This study is a randomized controlled trial, assessing the effect of a single platelet rich plasma (PRP) injection in post traumatic (concussive) greater occipital neuralgia. This study will compare the effects of a single PRP injection to injection with steroid and anesthetic. There will also be a third arm to the study, in which patients will receive an injection with normal saline. This study will assess the severity and frequency of headache symptoms before and after receiving the injection.

Each year, an estimated 69 million people suffer from traumatic brain injury/concussion worldwide. In most patients with concussion, symptoms improve within 3 months. However, in some persons, symptoms persist. The cause(s) of post-traumatic headache are not entirely clear, which limits treatment options. Sometimes, these headaches are caused by irritation to the greater occipital nerve, and pain originating from this area is called "greater occipital neuralgia". These headaches are often treated with steroid injections to the affected nerve. However, the effect of the injection is usually short lasting and may not provide adequate pain relief.

Therefore, other methods of treatment have been sought out. Platelet Rich Plasma (PRP) is an emerging biologic treatment. PRP contains high concentrations of platelets, growth factors, and anti-inflammatory molecules. PRP acts to reduce inflammation and encourage tissue repair at the site of injection. PRP is created by collecting a person's own blood, centrifuging it, and extracting the platelet-rich layer of plasma. This platelet rich mixture is then re-injected into the affected area. PRP is used as a safe and effective treatment in many fields, and is most commonly used in arthritis. PRP has recently been studied as a potential treatment for peripheral nerve disorders, such as carpal tunnel syndrome.

Post-injection, a daily headache diary provided via mobile application (Secure RedCap) available in iPhone or android device will be provided to record daily records of numeric pain rating scale, headache frequency and medication-use.

Inclusion Criteria:

• Eligible participants will be males or females at least 18 years of age who suffer from post-traumatic headaches secondary to GON. Patients must fulfill the ICHD-3 criteria in establishing a diagnosis of GON. This diagnosis will be established by an experienced Physiatrist with extensive experience in headache and related disorders. To meet this criteria, patients must have experienced previous successful temporary relief with local anesthetic or steroid injection surrounding the GON in the past, but have not received local steroid injection within past 3 months. Pre-treatment numerical pain rating scale for daily headache intensity must be ≥4/10, with a headache frequency ≥10 days/month. Possible secondary causes of ON must be ruled out with reasonable level of investigation prior to enrollment.

Exclusion Criteria:

• Inability to provide informed consent; history of surgery in the occipital region; unstable psychiatric or medical condition; rheumatologic or inflammatory disorders; widespread neurologic disorders (eg. MS); coagulopathy; immunosuppression; active cancer; herpes zoster infection in last 6 months; pregnancy; steroid or other local GON or LON infiltration in past 3 months.

There is no plan, all participant data will be kept on a secured REDCap database.

All members of the study will be blinded (participants and healthcare practioners) except for the study coordinator.