Page 200 Guide to Pain Management in Low-Resource Settings

188 Maged El-Ansary

of the catheter analgesia, the pain usually resumes and of time but is not permanent. Th erefore, it is only to
remains. Even in major pain management centers, this be used in cases of PHN associated with cancer where
technique is only used to control acute pain exacerba- life expectancy is less than 6 months. With careful use
tions, since long-term treatment would imply surgical of the technique, the complication rate for this patient
implantation of a catheter (intrathecally). Implanted group can be acceptable. Th e complication rate depends
catheters need highly specialized care and tend to fail on the site of ablation.
frequently, and therefore they are indicated only in very
special circumstances. Most conditions will respond af- Pearls of wisdom
ter 3–6 months of treatment.
Another rather simple option is counterirrita- • Postherpetic neuralgia is a multifactorial problem.
tion of the aff ected dermatome with transcutaneous • Prevention, early diagnosis. and aggressive treat-
electrical nerve stimulation (TENS). With a small and ment are of great importance.
simple device, an electrical current is applied to skin ar- • Postherpetic neuralgia is an alarming disease,
eas with a certain current and frequency, producing a sometimes hiding a more complicated health
nonpainful dysesthesia. With this treatment, the patient problem, and therefore diff erential diagnosis is
may have short-term or even long-term pain reduction. crucial. Management of PHN should go hand in
Th e mechanism for TENS is the blockade of pain trans- hand with a search for other pathology respon-
mission through the nerve fi bers responsible for touch sible for attenuating the immune-defense system.
(A-beta fi bers). Although the mechanism necessary to • Diff erent modalities are to be used to treat the
apply the electrical stimulation is simple, unfortunately condition because most of the time no single line
TENS devices available on the market are expensive, of treatment is eff ective.
and therefore should be given to patients on a rental ba- • Once PHN is established, it has some complica-
sis. Some patients respond well, and others not, but be- tions of its own. Th ese will range from lack of
cause TENS is simple and inexpensive, it could be used sleep, joint stiff ness, secondary infections, and
in developing countries and also by the non-pain spe- vascular strokes up to suicide attempts. Th us,
cialist, such as a general practitioner. It cannot be used adequate diagnosis and treatment of acute her-
on the head or neck or in pregnant women. pes zoster and postherpetic neuralgia should be
Th e successful use of TENS helped to develop expected—and to a certain extent this is possible
implantable electrodes for direct stimulation of the spi- in most patients—from the caring physician or
nal cord, for a therapy known as spinal cord stimulation other health care worker.
(SCS). Even in high-resource countries this technique
is only used in selected patients with PHN. Th e same References
applies to cryoanalgesia and radiofrequency. All these
techniques are outside the scope of this manual because [1] Baron R, Saguer M. Mechanical allodynia in postherpetic neuralgia:
evidence for central mechanisms depending on nociceptive C-fi ber de-
they are highly sophisticated, very expensive, and re- generation. Neurology 1995;45(12 Suppl 8):S63–5.
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pi A, Laippala P, Nurmikko T. CSF and MRI fi ndings in patients with
Another simpler option, which might be used acute herpes zoster. Neurology 1998;51:1405–11.
by a therapist experienced in block techniques, most [3] He L, Zhang D, Zhou M, Zhu C. Corticosteroids for preventing
postherpetic neuralgia. Cochrane Database Syst Rev 2008;1:CD005582.
likely an anesthesiologist, is ablation of nerves (e.g., the [4] Nurmikko T. Clinical features and pathophysiologic mechanisms of
postherpetic neuralgia. Neurology 1995;45(12 Suppl 8):S54–5.
intercostal nerves) by phenol in water (6%) or alcohol [5] Rice AS, Maton S. Gabapentin in postherpetic neuralgia: a randomised,
(60%). Th is treatment is eff ective for prolonged periods double blind, placebo controlled study. Pain 2001;94: 215–22.