Changes in Somatosensory-Evoked Potentials in Limb Lengthening

Lee, Duk Yong; Han, Tai Ryoon; Choi, In Ho; Lee, Choon-Ki; Chung, Sung Soo

doi:10.1097/00003086-199212000-00037

Cited by 19 publications

(6 citation statements)

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“…The electrophysiological properties of nerves are affected by the extent of nerve elongation. 2,3,24 These results are similar to our previous experimental study of rabbit sciatic nerves after gradual limb lengthening (0.5 mm/day), which showed no evidence of segmental demyelination but straightening of the geometry of the paranodal myelin sheath with mild conduction slowing. 24 With regard to behavioral assessment, a number of studies have reported threshold reduction by using neuropathic pain models.…”

Section: Discussionsupporting

confidence: 90%

“…Gradual nerve elongation is believed to be the primary cause of this form of injury because studies have demonstrated a clear correlation between the extent of lengthening and the degree of conduction slowing. 1,2 However, most of these basic studies have considered only the morphological and electrophysiological alterations in the elongated nerve; 3,4 therefore, the pathophysiological mechanisms underlying chronic nerve-stretch injury are not fully understood.…”

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Altered expression of sodium channel distribution in the dorsal root ganglion after gradual elongation of rat sciatic nerves

et al. 2009

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To elucidate the pathophysiological mechanisms underlying chronic nerve-stretch injury, we gradually lengthened rat femurs by 15 mm at the rate of 0.5 mm/day (group L, n ¼ 13). The control groups comprised sham-operated (group S, n ¼ 10) and naive (group N, n ¼ 8) rats. Immediately after the lengthening, we performed a conduction study on their sciatic nerves and harvested samples. Electrophysiological and histological analyses showed mild conduction slowing and axonal degeneration of unmyelinated fibers in group L rats. Altered mRNA expression of the voltage-gated sodium channels in the dorsal root ganglion was also observed. Tetrodotoxin-resistant (TTX-R) sodium-channel Nav1.8 mRNA expression was significantly decreased and TTX-R sodium-channel Nav1.9 mRNA expression showed a tendency to decrease when compared with the mRNA expressions in the control groups. However, tetrodotoxin-sensitive (TTX-S) sodiumchannel Nav1.3 mRNA expression remained unaltered. The immunohistochemical alteration of Nav1.8 protein expression was parallel to the results of the mRNA expression. Previous studies involving neuropathic states have suggested that pain/paresthesia is modulated by a subset of sodium channels, including downregulation and/or upregulation of TTX-R and TTX-S sodium channels, respectively. Our findings indicate that Nav1.8 downregulation may be one of the pathophysiological mechanisms involved in limb lengthening-induced neuropathy. Keywords: sodium channel; limb lengthening; peripheral nerve; nerve elongation; dorsal root ganglion Limb lengthening is a popular method of treating leg length discrepancies or congenital anomalies, but the technique could cause peripheral nerve injury. Gradual nerve elongation is believed to be the primary cause of this form of injury because studies have demonstrated a clear correlation between the extent of lengthening and the degree of conduction slowing.1,2 However, most of these basic studies have considered only the morphological and electrophysiological alterations in the elongated nerve; 3,4 therefore, the pathophysiological mechanisms underlying chronic nerve-stretch injury are not fully understood.Clinically, the earliest symptom of neuropathy induced by limb lengthening is pain and/or paresthesia along the leg's sensory nerve distribution, 5 similar to neuropathy induced by other types of injuries. Several experimental models have been proposed for various types of nerve injuries, such as the axotomy model 6 and the sciatic nerve or spinal nerve ligation model. 7-9 These studies have identified that the underlying pathophysiology after nerve injury is closely associated with altered expression of the voltage-gated sodium channels (VGSCs) in the dorsal root ganglion (DRG). 10-12VGSCs consist of alpha and beta subunits. The mature channels in the plasma membrane are mainly composed of alpha subunits, 13 which have been further classified into two types on the basis of the differences in their physiological and pharmacological properties: tetrodotoxin-resistant (TTX...

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Section: Discussionsupporting

confidence: 90%

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confidence: 99%

Altered expression of sodium channel distribution in the dorsal root ganglion after gradual elongation of rat sciatic nerves

et al. 2009

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“…Nerves and vessels adapt in length during the distraction process and recover from temporary degenerative changes within 2 months after the halting of distraction [104]. Excessive gradual ( [20-30 %) or acute distraction ([15 %) may both lead to partial or complete loss of nerve potentials [121,122].…”

Section: Effects Of Bone Lengthening On Surrounding Tissuesmentioning

confidence: 99%

Current concepts of leg lengthening

Hasler

Krieg

2012

Journal of Children's Orthopaedics

101

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Any lower limb discrepancy may be equalised by conservative means (insoles, prosthesis and orthosis). However, their long-term acceptance is low in regard to function, costs, expenditure and appearance. Timely epiphysiodesis is the best option in uniplanar deformities with adequate remaining growth and for patients whose predicted final body height is above the 50th percentile. However, many patients present late or with multi-planar deformities, which warrant more sophisticated operative approaches. The history of surgical bone lengthening comprises 100 exciting years of struggling, development and ongoing learning. The initial strategy of acute or rapid incremental distraction had lasted almost half a century until Ilizarov recognised the benefits of biological periosteum-preserving osteotomies and incremental lengthening at slow rates (1 mm/day) at a 4 × 0.25-mm daily rhythm, well appreciated as callotasis. In parallel, ring and wire constructs made complex three-dimensional axial, translational and rotational bone moulding possible. Taylor Spatial Frames—built on hexapod strut-linked platform technology as known from flight simulators—took limb correction to a more reliable, more precise and aesthetical level, all the more that the whole process became web-based. It represents state-of-the-art methodology and technology for complex, multi-plane deformities. Due to the significant risk of secondary malalignment, indications for lengthening by unilateral fixation have shrunken to moderate amounts of length disparity and uni- to bi-planar deformities in patients with still open physes. Mechanical or motorised, minimally invasively placed nails prevent muscle fixation and, therefore, ease rehabilitation, increase patient comfort and potentially shorten the overall time of sick leave and refrain from sports activities. Hence, they offer a valuable alternative for low-grade complexity situations. It remains to be proved if the significantly higher implant costs are compensated by lower treatment costs. Overall, limb lengthening, particularly in combination with multi-planar deformity correction, can still be an arduous endeavour. In any case, wise judgement of the patient’s deformity, medical and biological situation, psychosocial environment, selection of the appropriate method and hardware, as well as meticulous operating technique by an experienced surgeon are the cornerstones of successful outcomes.

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“…A limitation of distraction osteogenesis is the extent to which lengthening is possible (14)(15)(16)20), while in one-stage lengthening a drawback is soft tissue compliance; this affects blood supply essential for the survival of grafted bone.…”

Section: Discussionmentioning

confidence: 99%

“…However, the procedure is somewhat cumbersome because it requires an external fixator and treatment takes a long time, it carries certain complications, and there are limits to the maximum permissible extent of lengthening for various reasons such as damage to nerves or muscles (1,3,5,(13)(14)(15)(16)(17)20). For the correction of bony deformities including those of the hand and foot require a relatively classic method of lengthening that involves bone grafting still has its value; donor site morbidity, however, is a problem (4,9,18,19).…”

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Changes in Blood Flow During One Stage Lengthening of Bone: An Experimental Study in Rats

Kwon

Chung²

2000

Scandinavian Journal of Plastic and Reconstructive Surgery and

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Distraction osteogenesis is a well-accepted method of bone lengthening. Its disadvantages, however, are that it requires an external fixator and takes a long time. One-stage lengthening therefore offers certain advantages. A first point of reference for the safe limits of this procedure might be the changes of blood flow, and this is also the crucial factor in deciding on the appropriate method of lengthening, particularly where the hand or foot is involved. Using a laser Doppler flowmeter we measured blood flow in the dorsum of the foot after using bilateral minimonofixators to lengthen the tibias of 15 Sprague-Dawley rats. They were lengthened in four stages: stage 0 (before lengthening); stage I--12.5%; stage II--25%; and stage III--31.25% of lengthening. The blood flow during stage I decreased to 79% compared to that of stage 0; 16% during stage II; and 1% during stage III. This study suggests that the maximal permissible extent of lengthening might be less than a quarter according to the blood flow as suggested by this animal model.

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Changes in Somatosensory-Evoked Potentials in Limb Lengthening

Cited by 19 publications

References 0 publications

Altered expression of sodium channel distribution in the dorsal root ganglion after gradual elongation of rat sciatic nerves

Altered expression of sodium channel distribution in the dorsal root ganglion after gradual elongation of rat sciatic nerves

Current concepts of leg lengthening

Changes in Blood Flow During One Stage Lengthening of Bone: An Experimental Study in Rats

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