Extreme Lateral Lumbar Interbody Fusion Surgery with a Robot-Assisted System in a Swine Model.

AIM: To evaluate the technical aspects of the Da Vinci Xi Surgical System in minimally invasive extreme lateral lumbar interbody fusion (XLIF) surgery in a swine model. MATERIAL AND METHODS: Endoscopic discectomy and XLIF cage insertion were performed using a robot-assisted system. The time taken and the pros and cons of each steps were recorded. RESULTS: A total of 4 ports were used for the surgical access; one for the camera, two for bipolar forcepses, and one auxiliary port for modified discectomy. Punch and curette were used for discectomy. The cage was inserted through the auxiliary port. Cage position was manipulated and checked by using the C-arm fluoroscopy. The operative time was 80 minutes. No complications or cage malposition was noted throughout the procedure. CONCLUSION: This study shows that the robot-assisted XLIF approach is safe and feasible, and helps to protect the neurovascular structures. Moreover, a high image quality was also obtained during the procedure.

Complementary Phenomena: Phantom Hand and Phantom Face.

After tissue or limb loss, the development of sensation and perception of the lost or deafferent tissue is defined as a phantom phenomenon. We investigated the presence of phantom phenomena in individuals who underwent a full face transplant as well as those who had a hand transplant. Specifically, we investigated sensory perception of the face on the fingers and sensory perception of the fingers on the face in three full face and four hand transplant patients. In all seven individuals, we used a brush to separately stimulate the right and left sides of the face or the palmar and dorsal faces of the hand. We then asked the individuals if they felt a sensation of touch on any other part of their body and, if so, to describe their perceptions. Changes in the regions of the primary sensory cortex representing the hand and face were defined using fMRI obtained via tactile sensory stimulation of the clinical examination areas. Two of the full face transplant patients reported sensory perceptions such as a prominent sensation of touch on their faces during sensory stimulation of their fingers. Three of the hand transplant patients reported sensory perceptions, which we referred to as finger patches, during sensory stimulation of the face area. In fMRI, overlaps were observed in the cortical hand and face representation areas. We consider the phantom hand and phantom face phenomena we observed to be complementary due to the neighborhood of the representations of the hand and face in the somatosensory cortex.

Replantation of forequarter amputation: Report of two cases with successful structural, motor and sensorial results.

Although there have been numerous reports of major replantation of upper extremity amputations, limited numbers of above-elbow amputation replantation have been reported. We present the technical details of two successful replantations of forequarter amputations in a nine-year-old girl and a three-year-old boy. In both cases, the forequarter was amputated due to avulsion traction injuries resulting in amputation including the entire upper limb, while the integrity of the scapula and parascapular muscles was maintained, with no injury to the glenohumeral joint. Replantation was performed, involving a shorter ischemia time with proper fixation, and vascular and neural repairs. Postoperative recovery was uneventful, and motor and sensorial acquisition were quite satisfactory during follow-up periods of 9 and 6 years, respectively. Proper fixation of the amputated part mimicking the original anatomy, radical debridement of avulsed vessels, and reconstruction of the defect using long vein grafts and neural repair while maintaining proper integrity are the most important factors in success. When the requirements are met, replantation of the forequarter in a child yields a superior outcome, from both the functional and esthetic perspectives. To the best of our knowledge, this is the first report in the English literature involving two sequential cases of such high-level replantation resulting in successful reacquisition of both viability and function.

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.

Transcranial magnetic stimulation induced early silent period and rebound activity re-examined.

Despite being widely studied, the underlying mechanisms of transcranial magnetic brain stimulation (TMS) induced motor evoked potential (MEP), early cortical silent period (CSP) and rebound activity are not fully understood. Our aim is to better characterize these phenomena by combining various analysis tools on firing motor units. Responses of 29 tibialis anterior (TA) and 8 abductor pollicis brevis (APB) motor units to TMS pulses were studied using discharge rate and probability-based tools to illustrate the profile of the synaptic potentials as they develop on motoneurons in 24 healthy volunteers. According to probability-based methods, TMS pulse produces a short-latency MEP which is immediately followed by CSP that terminates at rebound activity. Discharge rate analysis, however, revealed not three, but just two events with distinct time courses; a long-lasting excitatory period (71.2 ± 9.0 ms for TA and 42.1 ± 11.2 ms for APB) and a long-latency inhibitory period with duration of 57.9 ± 9.5 ms for TA and 67.3 ± 13.8 ms for APB. We propose that part of the CSP may relate to the falling phase of net excitatory postsynaptic potential induced by TMS. Rebound activity, on the other hand, may represent tendon organ inhibition induced by MEP activated soleus contraction and/or long-latency intracortical inhibition. Due to generation of field potentials when high intensity TMS is used, this study is limited to investigate the events evoked by low intensity TMS only and does not provide information about later parts of much longer CSPs induced by high intensity TMS. Adding discharge rate analysis contributes to obtain a more accurate picture about the characteristics of TMS-induced events. These results have implications for interpreting motor responses following TMS for diagnosis and overseeing recovery from various neurological conditions.

Medium latency excitatory reflex of soleus re-examined.

We aimed to study the receptor origin and postsynaptic potential profile of the medium latency reflex (MLR) response that develops in the soleus muscle when common peroneal nerve of antagonist tibialis anterior (TA) muscle is electrically stimulated. To achieve this aim, we electrically stimulated common peroneal nerve and recorded surface electromyography (SEMG) responses of soleus and TA muscles of informed volunteers. Additionally, we recorded intramuscular EMG from the soleus muscle. Stimulation of common peroneal nerve induced a direct motor response (M-response) in the TA and MLR in SEMG of the soleus. Using voluntarily-activated single motor units (SMUs) from the soleus muscle we noted that there were two distinct responses following the stimulus. The first response was a reciprocal inhibitory reflex probably originating from the antagonist muscle spindle primary (Ia) afferents. This was followed by an indirect reflex response activated by the contraction of the TA muscle during the M-response. This contraction generated a rapid acceleration in the direction of dorsiflexion hence inducing a stretch stimulus on soleus muscle. The response of soleus to this stimulus was a stretch reflex. We suggest that this stretch reflex is the main contributor to the so-called soleus MLR in the literature. This study illustrated the importance of using SMUs and also using discharge-rate based analysis for closely examining previously 'established' reflexes.