Disordered and peculiar behavior is one of the clinical manifestations of mental disorder associated with intracranial tumor. Mental disorder associated with intracranial tumor refers to the mental disorder associated with the invasion of brain parenchyma by intracranial tumor and compression of adjacent brain tissues or cerebral blood vessels, resulting in destruction of brain parenchyma or increase of intracranial pressure, and about 40% to 100% of patients suffering from intracranial tumor can develop mental symptoms. How to diagnose behavioral disorders and peculiar? The clinical manifestations are diverse, sometimes the symptoms are atypical in early stage, and when the basic features of tumor are available, the condition is often advanced. Brain tumor develops slowly, and the first symptoms are increased intracranial pressure such as headache, vomiting and neurological localization symptoms such as muscle weakness, epilepsy, etc. After weeks, months or years, the symptoms increase and the condition worsens. In acute cases, the disease may deteriorate suddenly within a few hours or days, falling into paralysis, coma, complicated by diffuse acute cerebral edema, or death due to sudden obstruction of the cerebrospinal fluid circulation pathway by the tumor (cyst), resulting in a sharp increase in intracranial pressure, leading to brain herniation. General symptoms (1) Physical symptoms Headache, nausea and vomiting, optic disc edema and vision loss are the three main manifestations of increased intracranial pressure caused by brain tumor. Headache: The headache is episodic at the beginning, mostly in the morning and evening, and then increases during the day. ②Vomiting: it occurs mostly in the early morning or on an empty stomach, and vomiting is more common when the headache is severe, and most patients are accompanied by nausea. (2) Psychiatric symptoms (2) Psychiatric symptoms The general psychiatric symptoms of intracranial tumor include blurred consciousness, amnesia syndrome, dementia, and less common bipolar-like and schizophrenic-like psychosis. (1) Blurred consciousness: Blurred consciousness is a general symptom of brain tumor, which can be manifested in different forms and variability, and can be seen in rapidly developing tumor in any part of the brain, which belongs to acute organic brain syndrome, difficulty in understanding and responding, slow action, slow reaction, dullness, drowsiness, inattention, emotional indifference, disorientation, and also can occur in episodes of blurred consciousness or coma. Amnesia syndrome: Patients may show early decompensation or amnesia of recent events, and the memory of past experiences cannot be recaptured, or even new memories are distorted, but generally immediate memory can remain relatively good, and the disease may develop disorientation, paracrine amnesia and Korsakoff syndrome with fictitious phenomena. (3) Dementia: Patients with slow-growing, long-standing brain tumors may exhibit dementia, manifesting as deficits in calculation, comprehension, and judgment, which may be detected early due to inability to adapt to work, while rapidly infiltrating glioblastoma multiforme may also develop mental decline soon after the onset of disease. This suggests that there may be specific brain tumors that can cause schizophrenia-like psychosis. The clinical course of such cases is similar to that of schizophrenia, but the illness is brief and the delusions are not absurd. ⑤ Affective disorders: intracranial tumors with affective disorders are less common, but generally they are usually seen as indifference and depression, indifference to external things, dullness and lack of initiative. It is also seen as crying and laughing for no reason, mood instability, irritability, depression, crying, irritability, anxiety; especially temporal lobe tumor, intracranial tumor with manic episodes is rare, frontal lobe tumor patients show childish, occasionally see euphoric symptoms. (6) Psychotic reactions occurring on a psychogenic basis: Whether it is psychotic reactions occurring due to the patient’s attitude toward intracranial tumors or transient psychotic reactions after surgery, there is a psychogenic basis, and it is also related to the patient’s premorbid personality. Compensatory behaviors for organic defects are nonspecific and are seen in brain injury and other organic brain diseases, see the chapter on mental disorders associated with craniocerebral injury. (7) Personality change and behavioral abnormalities Patients show lack of initiative, reduced interest, lazy life, passive behavior, lack of neatness, lack of shame, no initiative to eat, sitting or bedridden, silent, or even similar to wood stiffness; some may shout, run around, or collect obscene things, personality change, behavioral abnormalities and intelligence change often appear at the same time. (1) Frontal lobe The frontal lobe is located in front of the central sulcus and above the lateral fissure. The dorsal and lateral surfaces of frontal lobe are supplied by middle cerebral artery, while the medial surfaces are supplied by anterior cerebral artery. ①Random movement: frontal impulses reach the contralateral cerebellar hemispheres via the cerebral bridge, and ataxically regulate the random movement. (3) Mental activity: mainly manifesting mental dullness, indifferent expression, impaired memory, attention, comprehension and judgment, decreased thinking and synthesis ability, inattention to neatness, unawareness of urination and defecation, sometimes strong grip and groping reflexes, and damage to the main hemisphere may result in aphasia. (2) Corpus callosum Surgical removal of the corpus callosum does not produce any symptoms, while severe psychiatric symptoms caused by tumors in the corpus callosum are more common than in other parts of the body, mainly due to the damage to the adjacent frontal lobe, mesencephalon and midbrain. 92% of tumors in the masticatory part of the corpus callosum show psychiatric symptoms, 57% in the middle part and 89% in the pressure part. (3) Temporal lobe In temporal lobe tumor, psychiatric symptoms are tactile, with increased intracranial pressure, visual field defects, sensory aphasia, epilepsy, psychotic automatism, hallucinations, and deep lesions may present with contralateral isotropic hemianopia or ¼ visual field defects.