Sudden Foot Research Articles

Comparison of the temporal properties of medium latency responses induced by cortical and peripheral stimulation

Sudden foot dorsiflexion lengthens soleus muscle and activates stretch-based spinal reflexes. Dorsiflexion can be triggered by activating tibialis anterior (TA) muscle through peroneal nerve stimulation or transcranial magnetic stimulation (TMS) which evokes a response in the soleus muscle referred to as Medium Latency Reflex (MLR) or motor-evoked potential-80 (Soleus MEP80), respectively. This study aimed to examine the relationship between these responses in humans. Therefore, latency characteristics and correlation of responses between soleus MEP80 and MLR were investigated. We have also calculated the latencies from the onset of tibialis activity, i.e., subtracting of TA-MEP from MEP80 and TA direct motor response from MLR. We referred to these calculations as Stretch Loop Latency Central (SLLc) for MEP80 and Stretch Loop Latency Peripheral (SLLp) for MLR. The latency of SLLc was found to be 61.4 ± 5.6 ms which was significantly shorter (P = 0.0259) than SLLp (64.0 ± 4.2 ms) and these latencies were correlated (P = 0.0045, r = 0.689). The latency of both responses was also found to be inversely related to the response amplitude (P = 0.0121, r = 0.451) probably due to the activation of large motor units. When amplitude differences were corrected, i.e. investigating the responses with similar amplitudes, SLLp, and SLLc latencies found to be similar (P = 0.1317). Due to the identical features of the soleus MEP80 and MLR, we propose that they may both have spinal origins.

Spontaneous intraneural hematoma of the common fibular nerve due to oral anticoagulation.

Compression syndromes affecting the common fibular nerve are common and frequently caused by direct pressure upon the fibular tip region. Here, we describe a case of a 50-year-old male presenting with sudden foot drop, which had developed spontaneously. He was on oral anticoagulants due to hereditary thrombophilia (factor-V-Leiden). Neurophysiology examination revealed a common peroneal nerve lesion at the fibular tip. T1-weighted magnetic resonance imaging (MRI) showed a not further classifiable hyperintensity within the common peroneal nerve. Surgical exploration revealed a diffuse intraneural hematoma, which was not evacuated. During follow-up, the nerve function recovered almost completely. In retrospect, MRI findings indicated a hematoma supported by the history of anticoagulant medication.

P24-F Medium latency Soleus reflex responses induced by transcranial magnetic and peroneal nerve stimulation

Background Sudden foot dorsiflexion generates medium and long latency responses in soleus muscle which are thought to be the stretch reflex and have a spinal origin. Peroneal nerve stimulation results in foot dorsiflexion and produces a medium latency reflex in soleus muscle (SOL-MLR). Similarly, transcranial magnetic stimulation (TMS) of motor cortex corresponds to the leg area evokes a response analogous to SOL-MLR, referred to as soleus motor evoked potential 80 (SOL-MEP 80). Material and methods In this study, the origin of SOL-MLR and SOL-MEP 80 were investigated in 15 healthy volunteers using surface electromyography. SOL-MEP 80 was evoked by non-invasive TMS of leg area of motor cortex on the scalp using a round coil. On the other hand, SOL-MLR was obtained through electrical stimulation of the peroneal nerve during the foot was slightly dorsiflexed. Given that the contraction of the tibialis anterior (TA) muscle results in foot dorsiflexion, so, the stretch reflex in the soleus muscle. Therefore, the latency of SOL-MLR and SOL-MEP 80 was compared with the muscle action potential generation in TA muscle with similar methodology, TA direct motor response and TA MEP. Results The latency difference between SOL-MLR and TA direct motor response was 64.0 ± 4.0 ms while the difference was 61.4 ± 5.6 ms between SOL-MEP 80 and TA-MEP. Conclusions Comparable latency features and similar behavior pattern of the responses propose that SOL-MLR and SOL-MEP 80 may have a related origin. This project (3135) supported by Akdeniz University Scientific Research Unit .

Shank Muscle Strength Training Changes Foot Behaviour during a Sudden Ankle Supination.

BackgroundThe peroneal muscles are the most effective lateral stabilisers whose tension braces the ankle joint complex against excessive supination. The purpose of this study was to identify the morphological and biomechanical effects of two machine-based shank muscle training methods.MethodsTwenty-two healthy male recreationally active sports students performed ten weeks of single-set high resistance strength training with 3 training sessions per week. The subjects conducted subtalar pronator/supinator muscle training (ST) with the right leg by using a custom-made apparatus; the left foot muscles were exercised with machine-based talocrural plantar and dorsiflexor training (TT). Muscle strength (MVIC), muscle volume and foot biomechanics (rearfoot motion, ground reaction forces, muscle reaction times) during a sudden ankle supination were recorded before and after the intervention.ResultsCompared to TT, ST resulted in significantly higher pronator (14% vs. 8%, P<0.01) and supinator MVIC (25% vs. 12%, P<0.01). During sudden foot inversions, both ST and TT resulted in reduced supination velocity (-12%; P<0.01). The muscle reaction onset time was faster after the training in peroneus longus (PL) (P<0.01). Muscle volume of PL (P<0.01) and TA (P<0.01) increased significantly after both ST and TT.ConclusionAfter both ST and TT, the ankle joint complex is mechanically more stabilised against sudden supinations due to the muscle volume increase of PL and TA. As the reduced supination velocities indicate, the strength training effects are already present during free-fall. According to a sudden ankle supination in standing position, both machine-based dorsiflexor and pronator strength training is recommended for enhancing the mechanical stability of the ankle.

Effects of Short and Medium Latency Reflexes of the Plantae Muscle with Ankle Vibration during Sudden Foot Movement

[Purpose] This study examined the influence of signals from ankle joint afferent fibers on the reflexive plantae muscle activity during standing subjects. [Subject] Ten male healthy adults participated in this study. [Methods] The subjects stood with their eyes closed on a movable platform that was moved backward. Vibrators (about 90 Hz) were applied to the medial and lateral malleolus of both legs. The vibrators were turned off in the control condition. In the malleolus vibration (MV) condition, vibration stimulus was applied for one minute before the beginning of trials and was continued during the trials (about six minutes). The short (SLR) and medium latency reflex (MLR) of the flexor digitorum brevis muscle (FDB) electromyogram (EMG) responses of the left leg during the platform translations were measured under the control and MV conditions. [Results] The latencies of the FDB SLR and MLR during MV condition were observed to increase significantly in comparison to the control. The integration EMG response values (iEMG) of the SLR and MLR significantly decreased during MV condition. [Conclusion] Excessive afferent signals from the ankle articular mechanoreceptors may participate in the reduction of the reflexive FDB SLR and MLR activities during standing postural perturbation due to changes in the excitability of inhibitory interneurons.

Sudden Foot Drop Caused by Foraminal Gas Pseudocyst

A foraminal gas pseudocyst is a rare cause of lumbar radiculopathy. The association with a sudden foot drop has not been previously reported. Here, a 67-year-old woman with sudden foot drop on the left side is reported. Computed tomography and magnetic resonance imaging identified a foraminal gas containing lesion compressing the left L5 root at the L5-S1 foramen. The foraminal gas containing lesion compressing the L5 ganglion was successfully removed by the posterior approach. The histological diagnosis was a gas pseudocyst. This unique case of surgically proven gas pseudocyst indicates that it should be included in the differential diagnosis of patients presenting with sudden foot drop.

The influence of shoe sole's varying thickness on lower limb muscle activity

The lateral ligament injury of the ankle is acknowledged to be the most common ankle injury sustained in sport. Increased peroneus longus muscle contraction in the shod population has already been documented. This study aimed to quantify the effect of shoe sole's varying thickness on peroneus longus muscle activity. Electromyographic recordings of the peroneus longus muscle activity following unanticipated inversion of the foot from 0° to 20° in a two-footplate tilting platform were collected from 38 healthy participants. The four test conditions were: barefoot, standard shoe, and shoes with 2.5 cm and 5 cm sole adaptation respectively. Compared to the barefoot condition, there is an increase in the magnitude of muscle contraction on wearing shoes, which further increases with thickening shoe soles. The peroneus longus was responding earlier in the shod conditions when compared to the barefoot, although the results were variable within the three shod conditions. Footwear with increasing shoe sole thickness evokes a correspondingly stronger protective eversion response from the peroneus longus to counter the increasing moment at the ankle-subtalar joint complex following sudden foot inversion. Hence, fashion footwear with thicker sole is likely to increase the risk of lateral ligament injury of the ankle when such protective response is overwhelmed. Similarly, the clinicians need to be cautious regarding the amount of shoe raise that they could provide for patients with limb length discrepancy without any detrimental untoward side effects.

Extraforaminal Lumbar Synovial Cyst Causing Sudden Foot Drop -Case Report-

A 52-year-old female presented with extraforaminal lumbar synovial cyst at the L4-5 level causing sudden foot drop on the right. Computed tomography, magnetic resonance (MR) imaging, and coronal MR myelography source images identified the cystic mass in the extraforaminal zone. The patient underwent microdecompression via a lateral transmuscular route, and the extraforaminal cyst compressing L4 ganglion was successfully removed. The histological diagnosis was synovial cyst. This unique case of surgically proven extraforaminal lumbar synovial cyst causing sudden foot drop indicates that extraforaminal synovial cyst should be included in the differential diagnosis of patients presenting with sudden foot drop.

Avaliação do tempo de resposta eletromiográfica em atletas de voleibol e não atletas que sofreram entorse de tornozelo

A proposta deste estudo foi examinar o tempo de resposta eletromiográfica dos músculos fibulares, na inversão repentina do pé, em tornozelos com presença de lesão e saudáveis. Três grupos foram testados, um de atletas normais (grupo 1), um de atletas com história recente de entorse de tornozelo (grupo 2) e o outro de não atletas com história recente de entorse de tornozelo (grupo 3). Para cada sujeito dos três grupos, ambos os tornozelos foram testados. Os sujeitos que sofreram entorse de tornozelo (grupos 2 e 3) não apresentavam sintomas de lesão durante os últimos dois meses antes do teste. Uma plataforma capaz de produzir uma inversão repentina lateral de 20° do tornozelo no plano frontal simulava um evento de entorse de tornozelo. Eletrodos de eletromiografia de superfície foram colocados na pele sobre os músculos fibulares. Os tempos de resposta eletromiográfica dos músculos fibulares foram obtidos e comparados entre os grupos. Para o grupo 1, a média dos tempos de resposta eletromiográfica foi de 71ms para a perna direita e 69ms para a perna esquerda. Para o grupo 2, a média dos tempos de resposta eletromiográfica foi de 72ms para o tornozelo sem lesão e 74ms para o tornozelo com a lesão. Para o grupo 3, a média dos tempos de resposta eletromiográfica foi de 72ms para o tornozelo sem lesão e 73ms para o tornozelo com a lesão. Os resultados indicaram que não houve diferença estatisticamente significante entre as pernas direita e esquerda no grupo 1 e entre os tornozelos sem lesão e com lesão dos grupos 2 e 3 para os músculos fibulares. Os achados do presente estudo sugerem que a resposta eletromiográfica dos músculos fibulares, durante o deslocamento angular repentino do tornozelo, não foi influenciada pela entorse de tornozelo.

Peroneus longus stretch reflex amplitude increases after ankle brace application

Background: The use of external ankle support is widespread throughout sports medicine. However, the application of ankle bracing to a healthy ankle over a long period has been scrutinised because...

ANKLE BRACING DOES NOT AFFECT PERONEUS LONGUS RESPONSE FOLLOWING MUSCLE FATIGUE

The potential effects of ankle bracing on joint proprioception have not been well established. In our laboratory, we have recently showed a facilitation in peroneus longus (PL) stretch reflex amplitude after immediate application of a ankle brace. There is evidence that suggests that ankle bracing may enhance proprioception by increasing afferent input from various mechanoreceptors. It has been shown that diminished joint force output, and impaired motor control occurs following muscular fatigue. Therefore, the purpose of this research was to establish if ankle bracing can minimize the negative consequences of muscular fatigue by enhancing neuromuscular function of the peroneus longus (PL) during sudden foot inversion. Fifteen healthy collegiate volunteers (age = 21.7 ± 3.2 yrs, ht = 172.5 ± 11.1 cm, and mass = 73.7 ± 12.0 kg) free from lower extremity pathology 12 months prior to the study and not engaged in a strength training program served as subjects. All subjects had PL neuromuscular function {magnitude (% of max amplitude) and latency (ms)} assessed during sudden foot inversion during two ankle brace conditions (control & lace-up) before and after a standardized isokinetic muscular fatigue protocol. A repeated measures ANOVA revealed that PL stretch reflex magnitude was unaffected (P > 0.05) by brace condition (control = 86.8 ± 1.3; lace-up = 86.3 ± 1.1) and fatigue (pre = 85.6 ± 1.4; post = 87.6 ± 1.4). Similarly, PL stretch reflex latency remained unchanged (P > 0.05) by brace condition (control = 52.9 ± 2.9; lace-up = 50.2 ± 2.3) and fatigue (pre = 51.5 ± 2.4; post = 51.6 ± 2.2). It appears from these data that muscle fatigue does not influence the reactive response of the PL during sudden foot inversion. Additionally, application of a lace-up style ankle brace does not affect PL latency and magnitude following an inversion perturbation.