### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
I have a hard knot at the base of my skull. It s hard and won t move but it s cause headaches and light sensitivity, also the headaches start right off the bump it feels. What could that be? I m not sure if they are related but I ve also had nose bleeds since this.

### output:

Thank you for your query. The base of your skull houses some important structures namely the occipital lobe (responsible for vision), brain stem (responsible for regulating important body functions like breathing, blood,heart rate and also houses several workhouses of the cranial nerves including the oculomotor which supplies the muscles of the eye) and blood vessels, contained in a narrow space, that supply the posterior part of your brain. Any space occupying lesion (SOL), a general term used to describe knots, bumps, tumors, in this area needs to be examined promptly especially as any pressure to adjacent structures, mentioned above, can cause compromise of these functions and Increased intracranial pressure. Nose Bleeds may occur to help relieve these symptoms. All your symptoms fit in this scenario. The SOL needs to be checked out right away by CT or an MRI of the brain and surrounding structures. Based on the size, type and other characteristics, a treatment plan will be made and initiated. This may include surgery to relieve pressure symptoms and effects. I recommend a prompt visit to your doctor to get it checked out.in the meantime, worsening of your symptoms, occurrence of new ones like, tremors, breathing difficulty, severe headaches, vomiting warrants a trip to the ER right away. Hope this helps, and you get better soon. Wish you good health and feel free to get back to us if you need any clarification