Simple semi-permanent blockade against rigid varus foot in a case with spasticity: possible practical benefits in ambulatory adults

Abstract

A 55-year-old ambulatory woman with hemiplegia and varus foot deformity had several problems in her daily life, including load pain and stance instability in the affected foot, easy fatigue of the non-paralysed leg, low back pain, neck stiffness and rapid shoe-rubber wear on the deformed side. We began repeated focal blockades using botulinum toxin to the tibialis posterior muscle to control varus spasticity. Distant influences presenting in the whole body were relieved soon after the first blockade, and shoe wear also stopped. Although, neither the deformed appearance nor foot contact pattern on walking changed in the initial period after beginning the blockade, the foot contact pattern revealed gradual improvement over several years. Generally, surgical correction is indicated for the treatment of deformed feet. The present case suggests that, in case of varus-deformed foot with some spastic elements, trial of focal blockade for varus spasticity may be worthwhile.

Background

Varus foot is a consequence of spasticity in patients with upper motor neuron disorders, and is a common type among the various spastic deformities of the foot (eg, varus, valgus, equinus, inversion, eversion, cavum, claw toes or combinations of these). An epidemiological study on post-stroke hemiplegic adults indicated that the incidence of varus foot was 18% within 1 year after the first stroke.¹

Placement of the varus afflicted foot on the ground produces an unstable support base during standing and walking due to unbalanced load distribution on the sole.² This promotes skin problems and/or pain in the affected foot, interferes with walking ability and, thereby, exacerbates difficulty in daily activities and reduces quality of life.

The present case with long-lasting hemiplegia since childhood showed a contracture on her spastic varus foot with motion limitation toward valgus. Although surgical correction is generally considered in such cases, we applied repeated focal blockades, using botulinum toxin (BoNT), for 5 years to the causative tibialis posterior muscle. Initially, neither the deformed appearance nor sole pressure pattern of the foot showed significant improvement. However, other beneficial effects were observed soon after starting simple blockade. The foot contact pattern showed gradual improvement over several years. The patient provided informed consent for publication of the findings.

Case presentation

A 55-year-old woman with hemiplegia since childhood, but living an independent life, presented with chronic foot deformity, recent decline of walking ability and other complaints.

Although she was born and grew normally as a baby, she suffered cerebral infarction at the age of 1 and consequently suffered paralysis of the right extremities. Although limited clinical information was available regarding this old event, she has suffered no other cerebral attacks since. At the age of 14, she underwent orthopaedic surgery for the deformity of the right foot. Based on her memory and surgical scars, the treatment was presumably performed on the gastrocnemius-soleus complex. She initially responded well after the surgery, but deformity of the same foot gradually recurred. Since reaching adulthood, she had experienced some inconvenience due to the foot deformity, but had been able to walk and to go outside alone without aid or orthoses. Therefore, she did not desire any further invasive treatment for the foot deformity, and had also not undergone any form of physiotherapy. She visited our institute after such a long interval due to some interest in BoNT therapy.

The right hemiplegia (Brunnstrom recovery stage IV) was accompanied with spasticity but no sensory disturbance. The right foot showed a moderate varus appearance with hindfoot inversion (figure 1). She presented with mild hypertonicity of the right ankle (modified Ashworth Scale score 1+), and the passive range of motion was moderately restricted to valgus (−15°) and mildly to dorsiflexion (0°). Plain X-ray showed no obvious findings of bony restraints against ankle mobility. Callosity with mild tenderness was formed on the lateral border of the right sole (figure 2).

Figure 1.

Deformity appearance of the right foot.

Figure 2.

Callosity on the sole of the deformed foot.

On visual inspection of her barefoot gait, obvious spastic increase on walking was noted on varus appearance, but not on equinus (video 1). She experienced mild pain on each ground contact of the right foot, probably caused by painful callosity. The upper body bent to the right in every walking-stance phase of the right leg, which may have been produced by an unstable stance and/or painful callosity. The medial part of the right sole containing the first toe did not make contact with the ground during walking, as revealed by plantar pressure analysis on walking using a measurement system (WinFDM; Zebris Medical GmbH, Isny im Allgäu, Germany) (figure 3A). Repeated measurements of 10 m walk test were timed around 9 s.

Video 1.

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DOI: 10.1136/bcr-2018-227732.video01

Barefoot gait before the treatment.

Figure 3.

Images of the plantar pressure analysis. (A) Before starting blockade treatment; (B) at 3 months after the first botulinum toxin BoNT injection; (C) at 45 months after starting blockade treatment (after four BoNT injections).

Other complaints were evening fatigue of the left non-paralysed leg, a dull pain in the lower back emerging on walking, and pain and stiffness over the right shoulder and neck. In addition, she reported problems with rapid wear of the rubber sole of the right shoe, especially on the lateral hind part, which developed within 3 months (figure 4).

Figure 4.

Shoe-rubber wear on the deformed side before starting blockade treatment. This used to develop rapidly within 3 months.

First, we recommended the use of an ankle-foot orthosis (AFO) with a short posterior leaf spring (short AFO). A trial over a few weeks indicated that a small AFO slightly improved her complaints, but she did not accept its use.

Differential diagnosis

• It is important to identify the type of contracture—that is, reversible, fixed or combined contracture—when considering the application of BoNT therapy. In the present case, combined type was highly probable. Although BoNT therapy would reduce varus spasticity in this case, it could be a part of varus deformity³ : that is, it was unclear whether BoNT therapy would resolve her fundamental complaints.

• There are two major types of varus foot, that is, forefoot-inversion and hindfoot-inversion.⁴ The first is often related to overactivity of the tibialis anterior muscle, whereas the second is usually related to overactivity of the tibialis posterior muscle. Hindfoot-inversion type is much more common, and was likely in our case. However, this type is mostly accompanied by equinus.⁵ Our patient did not show remarkable equinus appearance, which may have been due to previous orthopaedic surgery. Therefore, our case may be unusual among patients with varus foot. This resulted in some confusion in this case with regard to identifying the target muscles for BoNT therapy.

• To explore the appropriate target muscles, diagnostic injection using anaesthetic³ was performed on the possible causative muscles: tibialis posterior, tibialis anterior, flexor digitorum longus, soleus, gastrocnemius and some combinations of these muscles. Anaesthetic (0.5% mepivacaine) was delivered intramuscularly into the mid-belly of the muscle^{6 7} as a single amount of 4 mL for adjusting a single amount of BoNT injection. After each trial, temporary effectiveness was observed best when only the tibialis posterior (TP) muscle was injected, which brought satisfaction with ease of walking, relief of foot pain and improvement of stance stability.

Treatment

Type-A of the BoNT was injected at 2 weeks after the last anaesthetic injection. In Japan, the type-A toxin is dissolved at a dose of 12.5 UI/ml in saline solution for use on the lower extremities, and the standard dosing regimen for the TP muscle is 75 UI in adults. We prepared a dose of 50 UI (4 mL) for the present case because the calf muscles were atrophic. The solution was injected through an 80 mm 23-gauge needle into the mid-belly of the TP muscle under ultrasonographic guidance.

No additional interventions, such as physiotherapy and corrective casting, were performed. We recommended the use of a short AFO in daily life.

Outcome and follow-up

Within 1 month after the first BoNT injection, the foot pain on walking was reduced and the bending phenomenon of the upper body had improved somewhat on inspection (video 2). The effectiveness clearly emerged in regions distant from the right foot, ie, the lower back, shoulder and neck. Evening fatigue of the non-paralysed leg was also obviously alleviated. However, the foot contact pattern on walking examined at 3 months post-injection showed no remarkable improvement (figure 3B). There was also no remarkable change in the 10 m walk test, which was timed between 9 and 9.5 s.

Video 2.

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DOI: 10.1136/bcr-2018-227732.video02

Barefoot gait after the first botulinum toxin injection.

The patient has been followed up for 5 years since the first BoNT injection. To date, the same blockade with the same target muscle and the same dose of BoNT has been repeated five times. The next injection was usually planned when her complaints again became symptomatic. The short AFO was used when the complaints recurred. As a result, the intervals between the injections to date were 9, 12, 6 and 17 months in order from first to last. At present, 15 months has passed since the last BoNT injection. All of the initial complaints are satisfactorily under control. Serial analyses of foot contact patterns on walking suggested that the rigid part of the varus has improved slightly over a few years of follow-up (figure 3C). The 10 m walk test has changed little, and has been timed between 8.5 and 10.5 s; this suggests that her walking speed was already suitable as an ambulatory hemiplegic adult before BoNT therapy.

Unexpectedly, the rubber-sole wear of the right shoe stopped after starting blockade. She used to be forced to replace her shoes frequently, and still comments that this has been the greatest benefit of undergoing blockade treatment.

Discussion

The present case yielded some very interesting insights into the treatment of patients with varus foot. First, varus foot in ambulatory patients may cause various distant influences in the whole body, including effects on the lower back, neck and/or contralateral leg, probably due to the dynamic factors of walking that presented in posture and in many parts of the body. In addition, rapid shoe wear may also become a cause of stress in their daily lives. Second, despite the presence of rigid contracture in combination with spasticity, simple focal blockade still has unexpected curative potential. In our case, the subjective complaints, such as pain, leg fatigue and problems of shoe wear, were rapidly resolved by just one blockade. Third, a series of foot contact patterns suggested that repeated blockade had some potential to gradually improve rigid contracture over several years. This was unlikely to be due to blockade alone. In our case, daily weight loading by walking with use of an AFO under conditions of sustained suppressed varus spasticity could have supported the improvement.

Although the subjective complaints improved soon after beginning the blockade, objective findings that agreed with the subjective improvements were not found simultaneously in either deformed appearance or foot contact pattern on walking; that is, differences between the subjective and objective findings were observed in the initial years under repeated blockade. We postulated that enhancement of varus spasticity on walking may have been the primary cause of her complaints, including shoe wear and, therefore, BoNT injection into the TP muscle, which would quickly suppress the enhancement of varus spasticity on walking, may act as a direct clue to the improvements. However, mobility of the varus foot was initially rigidly restricted toward valgus, and therefore the objective improvements were not reflected simply in the deformed appearance or foot contact pattern in the early period.

A single application of focal blockade is generally considered to be ineffective for correction of refractory contracture deformity of the foot.³ Surgical procedures, such as muscle recession, tendon lengthening and tendon transfer, are generally chosen as standard initial treatments, as they have the advantage of rapid resolution of all problems at once. Focal blockade against rigid foot deformity may be a makeshift in comparison with surgical treatments. However, the present case suggested that the blockade should be preoperatively considered in cases of varus deformity underlain by spasticity. Patients who hesitate to undergo surgery may be suitable candidates for the blockade.

In cases in which focal blockade shows unexpected extensive effectiveness, a strategy of performing repeated blockades may be practical. BoNT therapy is the most common treatment for focal semi-permanent spasticity control, and several other procedures are also available, eg, motor nerve block,⁸ motor point block⁹ or muscle afferent block,⁷ which are performed using chemoneurolytic agents (phenol, ethanol) or thermocoagulation. The choice of technique is usually at the discretion of the clinician. However, it is not known whether repeated focal blockades may also have potential for improving soft tissue contracture. Considering the clinical course of our patient, it may take quite a long time until objective improvements are observed.

Finally, it is unclear whether the effects of repeated blockade will be long-lasting in our patient,¹⁰ and whether this strategy will show benefits in other similar cases. Moreover, the deformity in our patient was simple as it showed only varus. Therefore, it is unclear whether this strategy will also be effective against various conditions involving varus, such as combined type (eg, equinovarus foot) and severe type (eg, crab foot). Further studies with long-term follow-up and in larger numbers of patients are therefore needed.

Patient’s perspective.

The effect of surgical treatment did not last for many years; so I accepted all disabilities and troubles with my right foot. But after the start of botulinum toxin therapy, my daily life got better. The best surprise is that the rapid wear of the shoe rubber stopped soon after the first injection. Before starting the treatment, my shoe on the impaired foot did not last more than 3 months. Now my shoe lasts more than a year.

It is strange that some chronic symptoms on my back, neck and shoulder have gone after starting the injections. Although the injection site is a distal part of the leg, is there any connection between them?

Learning points.

• In the present case with rigid varus foot underlain by spasticity, focal blockade for varus spasticity brought about widespread effectiveness. The effects appeared soon after the first blockade.

• However, objective findings that agreed with quick relief of the complaints were not found in either deformed appearance or foot contact patterns on walking, probably due to the refractory restriction of valgus mobility.

• It is interesting that foot contact patterns improved gradually over several years by repeated blockade in our case.

• In conclusion, despite the presence of rigid contracture in varus foot, focal blockade for varus spasticity should be indicated in some cases under the understanding of its practical possibility and limitation.