Nerve injuries lead to impaired functioning of the nerve.
Analgesics, anti-inflammatory agents, anticonvulsants and antidepressants
provide limited relief.
neuroprotective pharmacologic factors such as L-carnitine and N-acetylcysteine
have shown good results in treating nerve injuries. Surgical repair of injured
nerves can also be done. There is still scope for better and effective ways to
restore functioning of nerves.
Nerve injury is the
commonest type of trauma sustained by nervous system and it is accountable for
Nerve damage can occur
due to penetrating traumas (stab wounds, surgical incisions, lacerations, etc),
crush trauma (fractures, compartment syndrome, hematomas, etc.) and stretch
Loss of functionality,
efficiency to recover and nerve component affected are important factors in the
classification of nerve injury.
Generally, two grading
systems are used in nerve injury:
I. Seddon's system
- In this
classification, three tiered model consisting of neurapraxia, axonotmesis, and
neurotmesis is taken into account for classifying nerve injuries.
is characterized by
local ischemia and demyelination of axon sheath.
a severe form of nerve
injury, is characterized by disruption of both myelin sheath and axons. It
results in Wallerian degeneration
process whereby 'the part of the axon that is separated from the neuronal cell
body disintegrates distal to the injury.' Axonotmesisis seen in displaced bone fractures and crush injuries.
is the most severe
kind of nerve injury and is characterized by disruption of endoneurium (connective tissue sheath
enveloping individual nerve fibers within a peripheral nerve)
and total nerve division. It is common in ischemic (restrictive blood flow to
tissues) injuries and lacerations.
II. Sunderland's system
- In this
classification, the last stage of Seddon's classification is further
sub-divided into three sub categories. The first subcategory is the same as the
last one in Seddon's system. In the second subcategory or the fourth degree
injury, both endoneurium and perineurium are injured and only the epineurium
remain intact. Surgical repair is required here. In the last subcategory or the
fifth degree injury, the lesion is a complete transaction of the nerve.
Recovery requires appropriate surgical treatment.
The damaged nerves do
not repair themselves instead 'intact areas take over the function of the
damaged areas in a process known as plasticity.'
The process of nerve
regeneration depends upon the type and nature of injury sustained.
Improving the quality
of life, restoring the normal functioning of injured nerves, and mitigating
nerve pain and discomfort are the chief goals behind the effective treatment of
nerve injuries. Both endogenous and exogenous sources of injury are to be
Nerve pain is
characterized by severe burning sensation and dysesthesia.
antiepileptics provide longer-acting effects. Narcotics are given for more
aggressive and severe forms of pain.
A number of pain
relieving agents are used for curing nerve pain such as analgesics,
anesthetics, antidepressants and anticonvulsants
They provide immediate
but short term pain relief benefits. Analgesics such as nonsteroidal
anti-inflammatory drugs, opioids and tramadol show poor response in nerve pain
Topical agents and
anesthetics also provide relief in pain caused by damaged nerves.
as tricyclic antidepressants (TCAs), serotonin-norepinephrine reuptake inhibitors
(SNRIs) and selective serotonin reuptake inhibitors (SSRIs) are efficient in
mitigating pain associated with nerve injuries.
Side effects such as
urinary retention, dry mouths, constipation, hypotension and dizziness are seen
Owing to the
similarity between functional changes of injury in neuropathy and epilepsy,
anticonvulsants are used in treating nerve pain.
as carbazepine and phenytoin are sodium channel blocker and have protective
abilities against neuropathic pain and seizures. Carbamazepine, though, is more
effective in reducing pain as compared with phenytoin.
Antiepileptics such as
lamotrigine, gabapentin, and oxcarbazepineare are also used in the management
of nerve pain. 'Gabapentin and pregabalin are particularly useful for
neuropathic pain in patients with a history of cardiovascular disorders,
glaucoma, or urinary retention.'
According to Cochrane
review, lacosamide offers very little or no benefits in mitigating neuropathic
pharmacologic management of pain, there are some nonpharmacologic therapies
that have proved effective in reducing
Transcutaneous electrical nerve stimulation
is one such type of nonpharmacologic therapy that has shown promising results
in managing nerve pain. In some patients, the endoneurial edema related with
peripheral nerve damage can be treated with steroids and antivirals.
The chief focus of
management of nerve injuries is neuroprotection.
drugs such as L-carnitine and N-acetylcysteine (NAC) have attracted scientists.
Both theses agents have antioxidant properties and are effective and safe in
The management of
nerve pain involves surgical
The significance of
surgical treatment lies in the fact that it is useful in repairing damaged
nerves, increasing the proportion of regenerating axons, and maximizing the
number of regenerating axons.
The best surgical
technique to allow the maximum number of axon regeneration is based on the
following factors -
extent of nerve
functional viability and location,
patient's age and
whether surgery can
restore functional ability to some extent with surgery, and,
outweigh risk, costs, and loss of productivity.
Further research is
required regarding associated symptoms and underlying cause of pain in order to
improve pain control in nerve injuries.
The author of the
review, Kiran Panesar, focused on the need to enhance the regeneration of
injured axons. However Kiran said that despite the significant advancement in
surgical techniques, the functional outcome of nerve injuries still remains
Management of Nerve Injuries; Kiran Panesar et
al; US Pharmacist