Page 205 Guide to Pain Management in Low-Resource Settings

Central Neuropathic Pain 193

How can I diagnose central hematomas usually present with headache and progres-
neuropathic pain? sive neurological symptoms, but central neuropathic
pain is an uncommon symptom in these cases.
Th e cornerstones of the diagnosis are a detailed his-
tory of development of symptoms and relieving and ag- How should the patient be treated?
gravating factors, and a careful neurological examina-
tion including sensory testing to touch, pinprick, cold, Treatment consists of:
warmth, and vibration. Abnormal sensory fi ndings sug- • Treatment of the causative disease, when possible
gest the possibility of neuropathic pain, and other neu- (e.g., medical and surgical treatment of epidural
rological fi ndings help to localize the site of the lesion. abscesses causing spinal cord compression).
It is important to keep in mind that the region of sen- • Secondary prevention (e.g., commencing ace-
sory abnormalities may be larger than the painful region tylsalicylic acid prophylaxis for atherothrom-
(Case 2). Diagnosing central neuropathic pain is actu- botic cerebral infarct, or treating endocarditis in
ally identifying symptoms and neurological signs com- a patient with embolus from an infected cardiac
patible with a lesion in the CNS, and excluding other valve).
possible causes of pain. Typical neurological fi ndings • Symptomatic relief of the neuropathic pain.
referring to a central neurological lesion are a positive • Treatment of other concomitant sources of pain
Babinski sign, accelerated tendon refl exes, and spastic- such as spasticity, which may exacerbate central
ity. Other possible causes of pain need to be excluded neuropathic pain.
with reasonable certainty. Careful clinical examination Th e fi rst line of therapy, after a thorough assess-
is usually suffi cient for this process, such as diagnosing ment, is information and education, for both the patient
musculoskeletal pain or pain due to local infection. and the family. For example, phantom limb pain is dif-
Diagnostic studies, such as neuroimaging and fi cult to understand for a layman. Th e doctor’s explana-
cerebrospinal fl uid analysis, may provide useful infor- tion in this situation may be very helpful (“your father
mation in reaching an accurate diagnosis, but they may is not crazy having pain where he has lost a limb”). Th e
not be available. In such conditions, recognition of the character of the pain, the disease causing it, and the
clinical features of the causative diseases is very useful. possibilities for pain relief need to be explained to the
Th e decision as to the use of limited resources and se- patient and the family. As symptomatic treatment of
lection of patients for referral is based on the possibili- central neuropathic pain is less successful than treat-
ties of treatment of the causative disease, such as with ment of peripheral neuropathic pain, giving thorough
neurosurgery. Spinal and cerebral abscesses, spinal trau- information may be the best way to help the patient.
mas with partial cord lesion, and spinal tumors are ex- Similarly to peripheral neuropathic pain, antide-
amples of conditions with radically improved prognosis pressants and anticonvulsants are used for symptomatic
with active surgical treatment. Cerebral abscess should treatment of central neuropathic pain. Amitriptyline
be suspected if a patient has fever and progressive neu- is the drug of choice for central poststroke pain. It is
rological symptoms (in cerebral abscess contralateral started with 10–25 mg in the evening, and the dose is
symptoms, and in spinal abscess sensory and motor de- escalated by 10–25 mg steps to 50–150 mg/day depend-
terioration below the level of the abscess). ing on the extent of side eff ects. Diffi culties in urination,
History of trauma before the onset of weak- constipation, dry mouth, and dizziness are typical side
ness of the limbs and sensory changes, including central eff ects, which may prevent further dose escalation. Ar-
pain, is suggestive of partial cord lesion. If there is an rhythmias caused by amitriptyline contraindicate its
unstable lesion of the vertebral column, quick stabilizing further use. If amitriptyline is intolerable or ineff ective,
surgery may prevent complete paralysis, and the same is carbamazepine can be tried instead. It is started at 100
true with laminectomies in spinal contusion with par- mg b.i.d., and the dose is escalated in 100-mg steps over
tial paresis. Slowly progressive paraparesis and sensory several days until 400–800 mg/day is reached. If side ef-
changes may be caused by a spinal tumor. Removal of fects (dizziness, headache, ataxia, or nystagmus) appear,
the tumor may prevent paralysis. Th e fi nal prognosis the dose should be reduced.
depends on the histology of the tumour and the severity Pregabalin has been shown eff ective for spinal
of the symptoms before surgery. Treatable intracranial cord injury pain, but it is not available in every country.