There are several anatomical locations where<unk>  electrodes are contraindicated: * Over the eyes due to the risk of increasing intraocular pressure * Transcerebrally * On the front of the neck due to the risk of an acute hypotension (through a vasovagal response) or even a laryngospasm * Through the chest using anterior and posterior electrode positions, or other transthoracic applications understood as "across a thoracic diameter"; this does not preclude coplanar applications * Internally, except for specific applications of dental, vaginal, and anal stimulation that employ specialized<unk>  units * On broken skin areas or wounds, although it can be placed around wounds * Over a tumor/malignancy (based on in vitro experiments where electricity promotes cell growth) * Directly over the spinal column<unk>  used across an artificial cardiac pacemaker (or other indwelling stimulator, including across its leads) may cause interference and failure of the implanted device. Serious accidents have been recorded in cases when this principle was not observed. A 2009 review in this area suggests that electrotherapy, including<unk> , is "best avoided" in patients with pacemakers or implantable cardioverter-defibrillators (ICDs). They add that "there is no consensus and it may be possible to safely deliver these modalities in a proper setting with device and patient monitoring", and recommend further research. The review found several reports of ICDs administering inappropriate treatment due to interference with<unk>  devices, but notes that the reports on pacemakers are mixed: some non-programmable pacemakers were inhibited by<unk> , but others were unaffected or auto-reprogrammed. The use of<unk>  is likely to be less effective on areas of numb skin or decreased sensation due to<unk>  damage. It may also cause skin irritation due to the inability to feel currents until they are too high. There's an unknown level of risk when placing electrodes over an infection (possible spreading due to muscle contractions), but cross contamination with the electrodes themselves is of greater concern.<unk>  should also be used with caution in people with epilepsy or pregnant women; do not use over area of the uterus as the effects of electrical stimulation over the developing fetus are not known.
Transcutaneous electrical nerve stimulation
Repetitive nerve stimulation
Percutaneous tibial nerve stimulation
Electrical muscle stimulation
Nerve conduction study
Nerve biopsy
Femoral nerve stretch test
Electromyography