For a patient with a tight headache, the following tests need to be performed depending on the situation: 1. Cerebral angiography (DSA) Although cerebral angiography is a more traumatic test for headache examination, it is the best test for vascular lesions such as aneurysms or venous sinus thrombosis that are difficult to detect with CT and MRI. Headaches that cannot be missed include those caused by intracranial entrapment aneurysms, which are more common in younger people. Those with hemorrhages have a dangerous prognosis of pain from subarachnoid hemorrhage on top of pain from damage to the vessel wall. Cerebral angiography can easily detect such lesions. 2, Electroencephalography An electroencephalogram is necessary for the diagnosis of epileptic headache. The presence of epileptic seizure waves is the main point of diagnosis. However, epileptic EEG abnormalities can sometimes be seen in patients with migraine, especially in certain pediatric headache patients with epileptic seizure waves and effective antiepileptic drugs. Most of them are simple partial seizures (autonomic seizures), which are characterized by a sudden onset of headache, often accompanied by nausea, vomiting, and postictal sleepiness or drowsiness, similar to migraine attacks. Some cases have both features, suggesting that there may be a pathophysiological correlation between the two. 3, cerebrospinal fluid examination For the suspicion of subarachnoid hemorrhage, headache accompanied by meningeal irritation or inflammation, headache of unknown cause, it is necessary to check the cerebrospinal fluid. Lumbar puncture examination can determine the level of cranial pressure, hemorrhage, yellowing and the presence of meningitis. Especially, cerebrospinal fluid examination is necessary to identify the causative agent of meningitis. However, if there is cervical ankylosis or optic nerve papillae edema, it should be considered that there is an increase in intracranial pressure, and at this time, lumbar puncture may cause hernia of the cerebellum due to a sudden decrease in cranial pressure and death, which is contraindicated in principle. 4, ophthalmology and otolaryngology examination Ophthalmologic diseases are also one of the causes of secondary headache. Especially in acute attacks of closed angle glaucoma, severe headache, eye pain, vomiting and vision loss can occur. Pupil asymmetry can also occur and may even be misdiagnosed as subarachnoid hemorrhage, which makes it necessary to check intraocular pressure. In addition, examination of the fundus suggests intracranial hypertension if optic papilla edema is found, and subarachnoid hemorrhage if subretinal hemorrhage is found. Some intractable headaches are caused by sinusitis. Sinusitis has characteristic symptoms depending on the location of the disease. For example, frontal sinusitis starts with pain in the forehead, the top, and the back of the eye orbits, and most of the headaches are worse in the morning after waking up and in the morning, and decrease in the afternoon. Maxillary sinusitis pain in the face, especially cheeks or ears, and radiates up the alveolar and frontal regions. Sieve sinusitis pain radiates temporally from the interorbital area, root of the nose, medial canthus, or retroorbital area. Pterygoid sinusitis presents with pain in the occipital, parietal, frontal, and retroorbital regions. These sinusitis can improve with appropriate treatment. The neurologist should refer the patient to an otolaryngologist for treatment based on these features.