Occupational cramp can be considered a relatively rare and unusual condition in clinical practice. Its main clinical manifestation is a task-specific focal abnormality of muscle tone that prevents the patient from successfully completing a specific action (e.g., writing, playing the piano, etc.). Writer’s cramp (often referred to as “writing hand”) is the most commonly reported condition, while the similar condition “musician’s cramp” is the most common. “Musician’s cramp and telegraphist’s cramp are less well known. The clinical manifestations are unusual because the patient’s reports and physical findings are often inconsistent, and in some patients, the affected finger is impaired in playing the piano but can play the violin or type without difficulty. There is no reliable and objective ancillary test to confirm the diagnosis, so it is easy to misdiagnose or miss the diagnosis if the doctor is not well informed. History The earliest records of this condition date back to the 1830s, when it was first reported by Bell and Bruck, and in 1893, Gowers gave a more detailed discussion of its clinical manifestations. In 1990, Sheehy and Marsden divided the broad spectrum of writer’s finger spasms into three categories: simple (simple) writer’s finger spasms, progressive (progressive) writer’s finger spasms, and spasticity. (progressive) writer’s finger spasticity and dystonia (dystonic) writer’s finger spasticity. In recent years, the use of botulinum toxin seems to offer hope for its treatment. The incidence of this condition has been poorly reported, with Butler finding an incidence of 42.25 per 100,000 for dystonia based on an epidemiological survey. The incidence of occupational dystonia, which is only one manifestation of dystonia, should be much lower than this value, and Nutt et al. calculated the incidence of occupational dystonia in the Rochester, Minnesota area from 1950 to 1982 to be 69 per million. There are numerous clinical reports showing that this condition occurs more often in middle age, with a prevalence of 30-50 years [3,5], and is significantly more common in men than in women, with Soland’s report specifying a 2.0:1 ratio of men to women, with a highly significant difference in incidence (p<0.01). Among musicians, piano and string players predominate, with some reports suggesting that they account for more than 85% of cases. About 70% of piano-playing patients have right-hand involvement, and the ulnar fingers of the right hand and the radial fingers of the left hand are susceptible; while 72% of violin-playing patients have left-hand involvement; for guitar-playing patients, abnormalities in the function of the middle, ring, and index fingers of the right hand and the index and ring fingers of the left hand are more common. The cause of this symptom is still not well understood, but there are many studies and speculations about it. However, recent electrophysiological and functional magnetic resonance imaging (fMRI) examinations have more often confirmed the existence of a central nervous system abnormality. Since this symptom is closely related to the patient's occupation, and most patients develop symptoms after many years in the occupation (musician's finger spasms occur in the vast majority of occupational musicians), its occurrence may also be related to certain (incorrect) occupational habits. 21 of these patients had preoperative writer's finger spasm, and of these patients, a total of 14 were followed up postoperatively, 13 of whom had complete resolution of symptoms. Taking into account the high prevalence of cervical spondylosis in the copywriting population, it seems more likely that the occurrence of writer's finger spasm may be associated with cervical myelopathy and, on the other hand, may be due to a central nervous system disorder. In his clinical practice, Milanov found that cranial tumors, infarcts, hemorrhages, or arteriovenous malformations can cause finger spasms. In his recent study, Preibisch used fMRI techniques to observe the oxygenation of cerebral blood flow during writing in patients with finger spasm in writers and normal subjects, and found that the activity of the ipsilateral cerebral hemisphere was stronger in patients than in controls, and the activity of the primary sensorimotor cortex was more in the anterior and posterior premotor areas. related areas, and dorsal thalamic activity was present only in the patient group during writing, thus suggesting increased output of the basal node in the patient brain and transmission to the motor cortex and premotor cortical areas via the dorsal thalamus. This also supports the idea that the development of the disease is associated with de-inhibition of the motor cortex. This finding is consistent with the findings using positron emission tomography (PET). Deuschl et al. conducted a paired study of patients with hand spasticity in writers using a movement-related cortical potential recording technique and showed reduced or absent activity in the motor cortex of the contralateral brain just prior to the initiation of casual movements of the affected limb. Since there is a positive family history in about 5% of patients and twin brothers have been reported to have the same disorder, some scholars have speculated that there may be some component of genetic background for this disorder. The most common symptom in patients with occupational finger spasticity is difficulty in completing a specific movement (holding a pen and writing, playing music, etc.), either in one finger or in several fingers simultaneously. In writer's finger spasm, when the patient is asked to hold the pen, it often fails to hold the pen tightly and slips involuntarily during the writing process, or involuntary movement of the affected finger occurs during the writing process and the writing becomes disorganized. For musicians with finger spasms, the affected finger cannot press the keys or strings forcefully at will during performance, resulting in missed notes, and some patients can even play normally at times and sometimes with impairment, which is not significantly related to the environment, fatigue, or whether they have practiced sufficiently. In addition to these manifestations, pain in the affected finger (limb) is uncommon, but some patients may complain of localized tension or discomfort in the affected finger or limb, and on examination may sometimes palpate striations along the muscles in the forearm; Marsden has even reported carpal tunnel syndrome as a result. Mild tremor may occur in about 1/3 of patients during writing or extension of the affected limb, and the occurrence of this tremor is limited to one side of the affected limb. Sheehy et al. classified the syndrome into three categories according to its clinical manifestations: first, simple writer's finger spasm, in which the patient only has difficulty writing without other motor deficits; second, progressive writer's finger spasm, in which the patient initially has simple writer's finger spasm, which gradually develops into a combination of some simple movements (e.g., combing hair, holding a cup, tray, etc.); and third, dystonic writer's finger spasm, which The third is dystonic dysgraphia, in which both writing and simple movements are impaired from the beginning. Diagnosis If the clinical features of occupational dactylopia are well understood, the correct diagnosis should not be difficult through detailed history taking and careful geographic examination. In case of doubt, one can also refer to electromyography (EMG) findings, which often show excessive synergistic contraction (cocontraction) of the active and antagonistic muscles of the affected limb, accompanied by prolonged abnormal neural discharges. Treatment and prognosis To date, it is generally accepted that occupational finger spasms do not require surgical treatment per se, but if they lead to carpal tunnel syndrome, surgical release is possible. Short-term spontaneous remission is achieved in only about 5% of patients, but most of them have recurrences. Longer follow-up studies have found a good prognosis, with no involvement of other muscle groups in the dystonia. Although these patients can be trained to write with the contralateral hand, about 20-25% will experience the same symptoms in the contralateral hand months or years later. Earlier, because occupational finger spasm was classified as a psychosomatic disease, suspension of writing (or playing), rest, physical therapy, and even hypnosis and psychotherapy were advocated, and some patients experienced symptom relief, probably because the specific causative operation was interrupted so that the lesion did not continue to develop, and certain lesions that could cause symptoms (such as cervical spondylosis) were improved through convalescence and physical therapy. Later, when the central nervous system lesion of occupational finger spasm was realized, almost all kinds of neuroactive drugs were tried, but no satisfactory results were obtained. Although oral anticholinergic drugs can improve the symptoms in 10-20% of patients, they make it difficult for patients to adhere to the medication because of their large side effects. β-blockers, which can also reduce tremor to some extent, have been abandoned for the same reason. In recent years, local injections of botulinum toxin into the most affected muscles of the forearm have been reported one after another with good results [8-10], which seems to open a new path for the pharmacological treatment of this disease. The choice of the muscle to be injected can be determined by the results of the electromyography recorded during writing, and the injections are given every 2 weeks until the symptoms improve. The main complications are weakness of the injected muscles and the body's immune response to the drug. For those patients who do not respond to medication, attempts can be made to reduce the inconvenience caused by the disease by changing the grip of the pen, switching to a thicker pencil, using a support or writing aid, etc. In conclusion, raising awareness of occupational finger spasm is a guarantee of correct diagnosis, and treatment can vary from person to person depending on the condition. In addition, for some patients with finger spasms secondary to cervical spondylosis, cranial tumors or vascular lesions, it is especially important to diagnose and treat the primary lesion. However, for some special populations (e.g., musicians), the disease should be actively treated as early as possible because it seriously affects their career development.