The invention relates to apparatus and methods for providing non-invasive stimulation of human tissue. More specifically, the invention relates to apparatus and methods for non-invasive stimulation to assist in assessing neuromuscular function.
There are many clinical and non-clinical situations that call for a rapid, reliable and low-cost assessment of neuromuscular function. The most common causes of neuromuscular disruption are related to pathologies of the peripheral nerves and muscles. Neuromuscular disorders, such as, for example, Carpal Tunnel Syndrome (CTS), are very common and well known to the general public. The disease is thought to arise from compression of the Median nerve as it traverses the wrist. The only objective way to detect CTS is to measure the transmission of neural signals across the wrist.
Formal nerve conduction studies (which can detect and monitor of neuromuscular pathologies such as CTS) are time-consuming, expensive, complicated, and require a trained medical expert. Moreover, these studies are not available in environments where early detection could significantly decrease the rate of CTS, such as the workplace where a significant number of causes of CTS appear. Thus, attempts have been made to make such diagnostic measurements available to non-experts. However, these devices and methods still demand a considerable level of expertise from the operator. For example, prior art devices typically require the operator to manually determine stimulation and detection parameters, such as the magnitude of the electrical stimulus. Prior art devices also typically do not automatically implement the diagnostic procedure and display readily interpretable results.
The invention relates to a system and method for stimulating human tissue using a master controller and a slave controller that communicate using a command language. In one embodiment of the invention, the system includes a master controller, a slave controller in signal communication with and electrically isolated from the master controller, and a stimulation circuit in electrical communication with the slave controller and having a stimulation output capable of providing an electrical stimulation to the human tissue. The master controller communicates at least one command comprising at least one parameter to the slave controller, and the slave controller controls said stimulation circuit to stimulate human tissue in response to the command comprising at least one parameter.
In one embodiment, the master and slave controllers communicate using a serial line. In another embodiment, the master controller transmits commands to the slave controller over a first communications channel, and the slave controller transmits commands to the master controller over a second communications channel.
In still another embodiment, the slave controller controls the stimulation circuit by converting the at least one command comprising at least one parameter into a sequence of control signals transmitted to the stimulation circuit. In another embodiment, the at least one command comprising at least one parameter comprises a plurality of commands.
In other embodiments of the invention, the system further comprises a sensor having an input terminal in electrical communication to the stimulation circuit and an output terminal in electrical communication to the slave controller, whereby the sensor monitors the stimulation circuit and transmits data related thereto to the slave controller.
In another embodiment, an apparatus of the invention comprises a controller having a plurality of input terminals and at least one output terminal and a stimulation circuit having a plurality of input terminals in electrical communication with the at least one output terminal of the controller, the stimulation circuit also having at least one stimulation output terminal. The stimulation circuit of this embodiment comprises a high voltage generator, a current stimulator, an amplitude control circuit, and a timing control circuit. The controller receives at the at least one input terminal at least one command comprising at least one parameter and transmits a signal to the input terminal of the stimulation circuit to stimulate the human tissue in response to the at least one command comprising at least one parameter.
One embodiment of the high voltage generator has an input terminal that is one of the at least one input terminals of the stimulation circuit and an output terminal. In one embodiment, the high voltage generator creates a high voltage signal accessible to the current stimulator in response to the signal transmitted to the input terminal of said stimulation circuit.
One embodiment of the current stimulator has a plurality of input terminals, and at least one of the plurality of input terminals is in electrical communication with the output of the high voltage generator. The current stimulator also has an output terminal capable of providing a current waveform to human tissue. In one embodiment, the current stimulator generates a current waveform in response to a signal transmitted to the input terminal of the stimulation circuit.
In another aspect, the invention comprises a method for delivering a stimulation signal to human tissue. This method includes the steps of receiving by a slave controller at least one command from a master controller that is electrically isolated from the slave controller, the command comprising at least one parameter, and stimulating the human tissue in response to the control signal. Other embodiments include the steps of converting the at least one command comprising at least one parameter into a sequence of control signals in response to the at least one command, and stimulating the human tissue in response to this sequence of control signals.