New Injection Points of Onabotulinum Toxin A for Spastic Paralysis of the Fingers: Eight Cases of Report.

OBJECTIVE: Onabotulinum toxin A (botulinum A toxin) is utilized to extend flexed extremities in spastic hemiparesis. Injection points are important to obtain a better effect. Injecting botulinum A toxin into the forearm muscles is a standard method for flexed wrist and fingers; however, we developed new injection points in the intrinsic muscles of the hand to acquire more reliable effect.
METHODS: The authors injected botulinum A toxin into the palmar side of the proximal and middle phalanx of each finger and thenar muscles. Eight patients with poststroke flexed wrist and fingers were treated by this method.
RESULTS: In all patients, the spasticity improved to 0 or 1 from 3 or 4 in Modified Modified Ashworth Scale 1 month after the treatment. They were satisfied with our treatment because they could keep their affected fingers hygienic by washing fingers cleanly after the treatment.
CONCLUSIONS: Our botulinum A toxin injection points for finger spastic paralysis are accurate spots producing great effect to flexed fingers. Copyright:

INTRODUCTION

Botulinum toxins are neurotoxic proteins produced by bacterium Clostridium botulinum and related species, and botulinum A toxin is one of the botulinum toxins arranged for medical use.[12] This toxin can effectively weaken muscle tone and is utilized for treatment of spastic hemiparesis in the upper and lower extremities caused by central nervous system disorders.[3456] For finger spasticity and stiffness, botulinum A toxin is injected into the extrinsic muscles of the hand, including flexor carpi radialis, flexor carpi ulnaris, flexor digitorum profundus, flexor digitorum superficialis, and flexor hallucis longus muscles.[7] However, the treatment is not so effective as the patients expect.

METHODS

This study was performed from April 2017 to March 2018. Study details were explained to each patient and family, and informed consent was obtained in written form with a signature. This article includes no information to identify individuals. Eight patients, who were unable to extend fingers in the hemiparesis side, were selected. In all the patients, the finger spasticity demonstrated the score 3–4 in Modified Modified Ashworth Scale (MMAS).[8] Botulinum A toxin (Botox: GlaxoSmithKline Japan, Tokyo, Japan) of 200 units was dissolved in 2 ml saline (10 units/0.1 ml). Thirty units of botulinum A toxin (0.3 ml) was injected into flexor pollicis longus, flexor digitorum superficialis, and flexor digitorum profundus muscles, respectively [Figure 1A]. Ten units of botulinum A toxin (0.1 ml) was injected into the palmar side of the proximal and middle phalanx of each finger (10 units × 9 points), and 20 units was injected into thenar muscles [Figure 1B]. All the injection procedures of botulinum A toxin were performed by one doctor.

Figure 1

(A)-(a) Standard injection points for finger spasticity injection into flexor pollicis longus (a), flexor digitorum superficialis (b), and flexor digitorum profundus (c) muscles are a general way for finger spasticity treatment. (B) New injection points for finger spasticity Botox injection into the palmer side of the proximal and middle phalanx of each finger (flexor carpi radialis and flexor carpi ulnaris muscles) are the new points. For injection into thenar muscles, two-point injection is recommended to acquire better effect. Each point needs 10 units of Botox

RESULTS

Epidemiology [Table 1]

In the eight patients (four males and four females), two males and two females became spastic hemiparesis because of intracranial hemorrhage and the others because of cerebral infarctions. The average age of the eight patients was 64.6 ± 11.6 years (43–76 years). The average duration from the onset of the diseases to the first botulinum A toxin injection was 52.6 ± 26.7 months (17–101 months). Their flexed fingers were very rigid with MMAS-3 in two patients and MMAS-4 in six patients.

Effectiveness of onabotulinum toxin a injection

For botulinum A toxin injection in the palmar side of the proximal and middle phalanx, each finger should be forcedly extended against the hypertonicity in all patients [Figure 2A-a]. No patients complained of pain when botulinum A toxin injection was performed in the fingers. One month after the injection, all patients could easily extend their wrist and fingers using their unaffected hand [Figure 2A and B] with MMAS-0 in four patients and MMAS-1 in four patients [Table 1].

Figure 2

(A) Botulinum A toxin injection targeting the intrinsic muscles of the hand. (a) Before injection: It is difficult to extend the fingers passively in the patients with spastic flexed fingers due to the rigidity of fingers (Modified Modified Ashworth Scale Grade 4), and for injection, each finger should be forcedly extended. (b) One month after injection: Although there is mild contracture in proximal and distal interphalangeal joints, all fingers are easily extended passively with minimal resistance (Modified Modified Ashworth Scale Grade 1) and the photo shows that the patient is easily extending his thumb with unaffected hand. (B) Botulinum A toxin injection into the intrinsic muscles of the hand. (a) Before injection: The wrist and fingers of the patient were flexed, and it was difficult for her to extend wrist and fingers by herself because of strong rigidity (Modified Modified Ashworth Scale Grade 4). (b) One month after injection: There is no increase in muscle tone in wrist and fingers after the treatment (Modified Modified Ashworth Scale Grade 0). The patient can move her wrist naturally and extend her affected fingers by putting her unaffected hand gently on the affected fingers

Table 1

Data of patients

Age (year)	Sex	Disease	Location of the lesions	Duration of hemiparesis (months)	MMAS before Tx	MMAS after Tx
43	Male	Hemorrhage	Left putamen	48	4	1
55	Female	Hemorrhage	Right putamen	17	3	0
59	Male	Hemorrhage	Left thalamus	76	4	1
65	Male	Infarction	Right internal capsule posterior limb	42	3	0
70	Female	Infarction	Right corona radiata	34	4	0
73	Female	Hemorrhage	Right putamen	38	4	1
76	Female	Infarction	Right corona radiata	65	4	0
76	Male	Infarction	Left corona radiata	101	4	1

MMAS=Modified Modified Ashworth Scale, Tx=Treatment

Satisfaction of the patients

The satisfaction of each patient to the treatment was evaluated by five grades: very satisfied, satisfied, neither, unsatisfied, and very unsatisfied. Six patients chose “very satisfied” and the rest of two “satisfied.” All the patients' families were also satisfied with our treatment because quantity of care decreased. The advantages after the treatment include the following: (1) the patients were able to wash the flexed fingers with soap and wipe up the water completely from the fingers with towel by themselves, (2) cut fingernails easily by themselves, and (3) they do not feel finger pain in hand rehabilitation. Some of them were pleased to have their meals putting a rice bowl or a saucer on the affected palm according to a Japanese custom. The botulinum A toxin treatment is performed every 4–6 months in all the cases.

DISCUSSION

Botulinum A toxin weakens muscle tones but does not improve hemiparesis itself.[123456] However, if their rigid flexed wrist and fingers due to muscle stiffness can be easily extended passively, the patients can live a better quality of life. The essential points in botulinum A toxin treatment are (1) excluding the patients who have contracture of joints in the wrist or fingers and (2) injecting sufficient amount of the drug into the accurate points. For finger spasticity and stiffness, injection of botulinum A toxin into flexor pollicis longus, flexor digitorum superficialis, and flexor digitorum profundus muscles is a standard way of the treatment.[6] However, through our experience of the treatment in several patients, the effect was not satisfactory for them. When we slightly bend only fingers separately, no movement of these muscles is recognized and only lumbrical and palmar interosseous muscles work. Furthermore, we can move proximal interphalangeal joints and distal interphalangeal joints without moving metacarpophalangeal joints. Based on the fact, the authors inject botulinum A toxin into the intrinsic muscles of the hand in addition to inject into forearm muscles for finger spasticity and stiffness [Figure 1B]. These intrinsic muscles arise from metacarpals and end at proximal phalanges. The injection into the palmar side of the proximal and middle phalanx of each finger and into thenar muscles was considered as new injection points, and the injection to the points did not cause pain to the patients. Our method provides an excellent effect of the extension of fingers unless the interphalangeal joints of the hand are not fixed as shown in Figure 2A-b and 2B-b. After our treatment, not only the patients but also their family got convinced of the importance of the botulinum A toxin treatment to reduce the load of caregivers. All of them chose “very satisfied” in the five grades to the treatment.

Another important point of botulinum A toxin treatment for the finger spastic paralysis is to target only finger and wrist joints to inject higher dose. Kaji et al. reported that the higher dose of botulinum A toxin was clinically more effective for the wrist and fingers without causing doselimiting adverse events.[9] Most patients with spastic hemiparesis have stiffness in the shoulder, elbow, wrist, and fingers. Insurance company covers the fee of up to 240 units of botulinum A toxin for injection in the upper limb,[9] and the dosage is extremely low to deliver the maximum dose in all portions. The patients are satisfied with the botulinum A toxin treatment when they obtain maximum effect in a certain portion rather than when they acquire halfway effect in all portions. Therefore, for fixed wrist and fingers, the maximum dose should be injected into muscles which flex the wrist and fingers.

CONCLUSION

Our botulinum A toxin injection points for finger spastic paralysis produce great effect to flexed fingers.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.