Headache is a symptom of pain observed in head, face and upper cervical dermatome. Headache is a complaint of discomfort originating from tissue covering brain such as meninges, skull, periosteum and structures of the skull base. In addition, pain also originates from blood vessels and muscles around brain, scalp, face, and neck. Cerebral cortex, cerebellum, midbrain, blood vessels and nerves occupy space within the skull.
Brain tissue is insensitive to pain since pain receptors are not detected in brain tissue. Headache is broadly classified as primary and secondary headache. Migraine, cluster and tension headache are primary headache. Space occupying lesion within skull causes secondary headache. Stretching of meninges by tumor, abscess and blood clot results in tension type secondary headache.
Secondary tension headache may incur because bony skull cannot expand with space occupying lesions. Increased tissue mass either tumor, abscess or blood clot within skull will cause increased pressure or compression of nerves and blood vessels. Occasional symptom of tension headache may be a warning sign of life threatening internal bleeding within compact bony skull.
Bleeding could be mild, moderate or severe and result in blood clot of variable size depending on blood volume. Initial symptoms of mild to moderate headache secondary to mild hemorrhage if ignored may result in continuation of internal bleeding and developing into massive blood clot. Massive blood clot will cause shift of cerebral vital centers towards the skull base and mid brain to the base of the skull.
Increased pressure and ischemia of vital brain centers will lead to life threatening symptoms such as slow breathing, slow heart rate, low blood pressure and respiratory apnea. Bleeding within brain tissue during initial phase may indicate mild to moderate headache. Later with time, continuous slow bleeding may cause severe headache with substantial increase in size of clot. In a few cases, time is essential and important to save life.