A Microchannel Neuroprosthesis for Bladder Control After Spinal Cord Injury in Rat
A Microchannel Neuroprosthesis for Bladder Control After Spinal Cord Injury in Rat
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DOI：
10.1126/scitranslmed.3007186
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发表时间：
2013-11-06
影响因子：
17.1
通讯作者：
Fawcett, James W.
中科院分区：
文献类型：
--
作者：
Chew, Daniel J.;Zhu, Lan;Fawcett, James W.
脊髓损伤的严重并发症是膀胱功能丧失（神经源性膀胱），其特征是膀胱感觉丧失和排尿自主控制（排尿），以及针对闭合括约肌的自发性过度反射性排尿（逼尿肌-括约肌协同失调）。低频骶前根刺激器可以驱动膀胱自主排尿，但需要对腰骶背根进行手术根切断术，以防止自发排尿和协同失调。然而，根切断术是不可逆的，并且会消除性功能，并且刺激器不会提供有关膀胱充盈度的信息。我们设计了一种闭环神经假体接口，可以测量膀胱充盈度并防止自发排尿发作，而无需在大鼠模型中进行背神经根切断术。为了获得膀胱感觉信息，我们将大鼠脊柱内的背根（细根）植入微通道电极中，从而提供信号放大和噪声抑制。只要附着在脊髓上，这些细根就能存活长达 3 个月，并且含有轴突和血管。电生理记录显示，一半的细根传播动作电位，放电频率与膀胱充盈度相关。当膀胱变得足够充盈以启动自发排尿时，检测到高频/振幅感觉活动。使用腹根高频去极化块消除了排尿。腹根刺激器以低频启动膀胱排空，并以高频防止不必要的收缩。这些数据表明，来自背根的感觉信息与腹根刺激器可以构成闭环膀胱神经假体的基础。
A severe complication of spinal cord injury is loss of bladder function (neurogenic bladder), which is characterized by loss of bladder sensation and voluntary control of micturition (urination), and spontaneous hyperreflexive voiding against a closed sphincter (detrusor-sphincter dyssynergia). A sacral anterior root stimulator at low frequency can drive volitional bladder voiding, but surgical rhizotomy of the lumbosacral dorsal roots is needed to prevent spontaneous voiding and dyssynergia. However, rhizotomy is irreversible and eliminates sexual function, and the stimulator gives no information on bladder fullness. We designed a closed-loop neuroprosthetic interface that measures bladder fullness and prevents spontaneous voiding episodes without the need for dorsal rhizotomy in a rat model. To obtain bladder sensory information, we implanted teased dorsal roots (rootlets) within the rat vertebral column into microchannel electrodes, which provided signal amplification and noise suppression. As long as they were attached to the spinal cord, these rootlets survived for up to 3 months and contained axons and blood vessels. Electrophysiological recordings showed that half of the rootlets propagated action potentials, with firing frequency correlated to bladder fullness. When the bladder became full enough to initiate spontaneous voiding, high-frequency/ amplitude sensory activity was detected. Voiding was abolished using a high-frequency depolarizing block to the ventral roots. A ventral root stimulator initiated bladder emptying at low frequency and prevented unwanted contraction at high frequency. These data suggest that sensory information from the dorsal root together with a ventral root stimulator could form the basis for a closed-loop bladder neuroprosthetic.