The causes of numbness in the left back of the head are mainly considered as follows: 1. The most common clinical cause is caused by plant nerve dysfunction, which can easily occur in patients with poor sleep, emotional anxiety, tension or excessive mental activity, and is a result of mental factors. 2. The symptoms of numbness in the left back of the head of patients may also be caused by scalp neuritis or other scalp neuropathy, such as The patient is not dry after washing the hair in the case of cold, wind blowing, easily lead to the patient’s subscalp nerve stimulation, will also appear the symptoms of numbness in the left back of the head. 3, considered cervical spondylosis caused by damage to the occipital nerve, mostly in the patient’s incorrect sleeping posture or after working too long, can be clarified by doing cervical spine CT imaging examination.