System and method for neurostimulation and/or neurorecording

1. A system for neurostimulation, the system comprising:

a first module comprising a pulse generator within a first housing;

a second module comprising a switch matrix within a second housing distinct from the first housing;

a connecting cable that connects the first module to the second module;

a grounding electrode disposed distal of the first module and proximal of the second module, wherein the grounding electrode is electrically coupled to the switch matrix of the second module; and

a plurality of electrodes disposed distal of the second module, wherein each electrode of the plurality of electrodes are selectively coupled to the pulse generator via the switch matrix.

2. The system of claim 1 , wherein the grounding electrode is configured to establish a defined return path for stimulation current delivered by the pulse generator to one or more electrodes of the plurality of electrodes.

3. The system of claim 1 , further comprising control electronics for the plurality of electrodes and the grounding electrode, the control electronics configured to at least one of provide neurostimulation current or sense neuro signals via at least one electrode of the plurality of electrodes and the grounding electrode, wherein the control electronics are arranged in at least one of the first module or the second module.

4. The system of claim 1 , wherein the grounding electrode is disposed closer to the second module than the first module.

5. The system of claim 1 , wherein the grounding electrode is configured to be implanted at least partially outside of a skull of a patient, and wherein the plurality of electrodes are configured to be implanted at least partially within brain tissue.

6. The system of claim 1 , wherein the grounding electrode is carried by the connecting cable.

7. The system of claim 1 , wherein the switch matrix is configured to select an electrode configuration from the plurality of electrodes and the grounding electrode for delivery of electrical stimulation pulses from the pulse generator.

8. The system of claim 1 , wherein the grounding electrode comprises at least one ring electrode.

9. The system of claim 1 , wherein the grounding electrode comprises at least one ring segment electrode, the ring segment electrode defining a circumferential arc greater than 180 degrees and less than 360 degrees.

10. The system of claim 1 , wherein the grounding electrode comprises a coil electrode.

11. The system of claim 1 , wherein the grounding electrode is at least partially formed by at least one of a laser cut-out, a laser pattern, or laser-ablation.

12. The system of claim 1 , wherein the grounding electrode is at least partially covered by at least one of an electrically conductive polymer or a noninsulative polymer.

13. The system of claim 1 , wherein the grounding electrode is a first grounding electrode, and wherein the system comprises a second grounding electrode coupled to the first grounding electrode via one or more conductors internal of the connecting cable.

14. The system of claim 1 , wherein the grounding electrode is a first grounding electrode, and wherein the system comprises a second grounding electrode, and wherein the first and second grounding electrodes are ring electrodes coupled by a coiled conductor disposed external of the connecting cable.

15. The system of claim 1 , wherein the connecting cable defines an axial lumen and access openings between the axial lumen and an exterior of the connecting cable for entry of body fluids, and wherein the grounding electrode comprises an electrically conductive wire disposed within the axial lumen.

16. The system of claim 1 , wherein the connecting cable is a first connecting cable, and wherein the system further comprises a second connecting cable disposed distal of the first module and proximal to the first connecting cable, the second connecting cable comprising:

a receptacle that receives connectors of the first connecting cable; and

at least one ring electrode at a distal end of the second connecting cable, the at least one ring electrode configured to define the grounding electrode and electrically couple to a contact of the first connecting cable.

17. The system of claim 1 , wherein a surface area of the grounding electrode is greater than a combined surface area of the plurality of electrodes.

18. The system of claim 1 , further comprising a lead electrically coupled to the switch matrix of the second module, wherein the lead comprises a thin film carrying the plurality of the electrodes.

19. A method for neurostimulation, the method comprising:

generating, by a pulse generator within a first housing of a first module, a stimulation signal;

transmitting, by a connecting cable that connects the first module to a second module comprising a switch matrix within a second housing distinct from the first housing, the stimulation signal to at least one electrode of a plurality of electrodes selectively coupled to the pulse generator via the switch matrix, the plurality of electrodes disposed distal of the second module; and

returning the stimulation signal to the first module via a grounding electrode disposed distal of the first module and proximal of the second module, wherein the grounding electrode is electrically coupled to the switch matrix of the second module.

20. A method for neurorecording, the method comprising:

measuring a brain signal between at least one electrode of a plurality of electrodes and a grounding electrode, the grounding electrode disposed distal of a first module comprising a pulse generator within a first housing and proximal of a second module comprising a switch matrix within a second housing distinct from the first housing, the first module and second module being connected by a connecting cable, and the plurality of electrodes disposed distal of the second module, wherein each electrode of the plurality of electrodes are selectively coupled to the pulse generator via the switch matrix, and wherein the grounding electrode is electrically coupled to the switch matrix of the second module.