Peripheral nerve stimulation (PNS) may be covered for relief of chronic
intractable pain for patients with conditions known to be responsive to this
form of therapy, and only after attempts to cure the underlying conditions and
appropriate attempts at medication management, physical therapy, psychological
therapy and other less invasive interventional treatments. As with spinal
nerve stimulations (spinal cord stimulators (SCS) are dealt with in a
companion policy), severe neuropathic pain is typically well suited for
successful responses to PNS. There may be rare selected situations where both
spinal cord stimulators and peripheral neurostimulators are used together.  
  
PNS refers to the placement of a lead by a physician (via open surgical or
percutaneous approach) near the known anatomic location of a peripheral nerve.
Peripheral nerve field stimulation (PNFS) refers to use of a lead placed to
stimulate the subcutaneous distal distribution of an area of pain (indirectly
stimulating the peripheral nerve). In both PNS and PNFS leads are composed of
multiple contacts (of varying number) connected to an external pulse generator
when temporary and implanted when made permanent.  
  
PNS, like deep brain stimulation and spinal cord stimulation modulates the
nervous system with electrical stimulation to lessen chronic pain and other
conditions. PNFS has an uncertain mechanism of action.  
  
PNS has been tried for over 50 years and has been used in a wide variety of
chronic pain syndromes, but the scientific literature is limited for many of
the indications tried. The most accepted uses of PNS involves one of two
methods:

  * Open exposure of a peripheral nerve and direct implantation of a PNS electrode (as in treatment of a radial nerve, sciatic nerve, median nerve, etc.).
  * Percutaneous insertion of a PNS electrode in direct vicinity of the stimulated nerve (e.g., occipital nerve for severe headaches).

As with a SCS and PNS, performance of an effective trial is a pre-requisite of
final implantation. Many experts recommend that the temporary neurostimulator
be placed in an Ambulatory Surgical Center (ASC) or outpatient hospital
setting. However, the temporary neurostimulator trial can be done in an office
setting if all the sterility, equipment, professional training and support
personnel for the proper surgery and follow up of the patient are available.
Permanent neurostimulators must be placed in an ASC or hospital. Physicians
performing PNS trials in place of service office must have like privileges at
an ASC or hospital, or the physician must be board certified or board eligible
in Pain Medicine, Orthopedic Surgery, or Neurosurgery by an ABMS Board or the
equivalent as determined by the state of practice. Other ABMS Specialty Boards
or the equivalent in the state of practice may be included if such practice is
included in the training program curriculum.  
  
It is preferable that the physicians performing the PNS trials will also
perform the permanent implant. If the physician implanting the trial PNS does
not or cannot implant the permanent neurostimulator(s), the patient should be
informed of this in writing and given the name of the referral surgeon who
will implant the permanent neurostimulator(s).

Coverage of PNS trials requires that patients have _all_ of the following:

  * Documented chronic and severe pain for at least 3 months,
  * Documented failure of less invasive treatment modalities and medications,
  * Lack of surgical contraindications including infections and medical risks,
  * Appropriate proper patient education, discussion and disclosure of risks and benefits,
  * No active substance abuse issues,
  * Formal psychological screening by a mental health professional, and
  * Successful stimulation trial with greater than or equal to 50% reduction in pain intensity before permanent implantation.

The only reliable predictor of PNS effectiveness is a trial of stimulation
with implanted PNS electrodes. If a trial fails, a repeat trial is usually not
appropriate unless there are extenuating circumstances that led to the trial
failure (equipment malfunction, early lead migration, etc.), technological
advances, or an alternative neuromodulary technique that may lead to a more
successful second trial. Documentation must explain these unusual situations.
It is expected that accurate patient selection will lead to most patients
going on to receive permanent implants. All trials which proceed to permanent
implant must have adequate documentation in the chart to support that
decision. A successful trial should be associated with at least a 50%
reduction of target pain, or 50% reduction of analgesic medications, and show
some element of functional improvement.  
  
Physicians with a low trial to permanent implant ratio less than 50% will be
subject to post payment review and may be asked to submit documentation as to
the patient selection criteria, the imaging demonstrating proper lead
placement, and the medical necessity of the trials. Failure to provide this
documentation will be cause for post-payment denial and recoupment of
reimbursement. It is understood that all patients may not have a favorable
result of the trial implant; but careful selection should find the most
appropriate patients.

Examples of peripheral stimulation indications with evidence of efficacy that
may be covered are:

  * PNS of occipital nerves for occipital neuralgia, post-surgical neuropathic pain, cervicogenic headaches and treatment resistant migraines.
  * PNS of trigeminal nerves (and branches) for post-traumatic and post-surgical neuropathic pain in the face related to the trigeminal nerves.
  * PNS of nerves in upper and lower extremities of complex regional pain syndromes (type 1 and 2), pain due to peripheral nerve injury, post-surgical scar formation, nerve entrapment, painful mononeuropathy, and painful amputation neuromas.
  * PNS of intercostal and ilio-inguinal nerves for post-surgical and post-traumatic neuropathic pain involving these nerve distributions.

Current peer-reviewed data DOES NOT SUPPORT PNS for fibromyalgia, phantom limb
pain, diffuse polyneuropathy, nociceptive pain in trunk or lower back, or
angina pectoris. Claims for these indications will be denied as not reasonable
and necessary. Current peer-reviewed data also is insufficient to warrant the
medical necessity of coverage for PNFS for any condition. Therefore, this
service will not be covered for any condition.

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