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  Nerve Pain       Post Traumatic Neuropathy      
 
 
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Introduction

Post Traumatic Neuropathy implies nerve pain (neuralgia, neuritis) that has come on either after an injury or as a consequence of medical interventions like surgery, injections, radiotherapy etc. It would be impossible to discuss every type of nerve damage, trapped or pinched nerve in every location. I have therefore concentrated on the common ones seen in the pain clinic. Which ever nerve is affected, there are similar clinical findings, investigations, and pain clinic treatments available for it. Rather than repeat these for each of the sections on this page, I have summarised them below:-

Clinical Findings

  • Symptoms are usually felt at the site of the injury, and also radiate away from the site in the normal distribution of the nerve involved. Detailed anatomical knowledge is required to be able to determine which nerve is involved.
  • Neuralgic quality pain (burning, shooting) associated with hypersensitivity, numbness, tingling, and muscle weakness depending on whether the nerve involved is purely sensory, purely motor, or mixed sensory / motor.
  • There may be associated over activity of the sympathetic nervous system in the area e.g. excessive sweating, colour changes (blue through to red), and temperature changes (cold through to hot).
  • Allodynia may be present. This is pain from a stimulus that does not normally cause pain:-
    • light touch = vibrational allodynia
    • pain at temperatures between 37 - 60 deg C (normal warm range) = heat allodynia
    • pain at temperatures between 4 - 37 deg C (normal cold range) = cold allodynia
  • Pressure with a finger over the site of the nerve injury will usually reproduce the nerve pain and symptoms. Also stretching a damaged nerve will have the same effect.
  • Examination may reveal nerve specific abnormal sensory and motor function.

Investigations

  • EMG is the investigation of choice where there is doubt about whether nerve function is normal or not. It can also be used to assess the recovery of a nerve injury over time.
  • MRI / CT scans can also be useful to assess structural damage to other tissues in the vicinity of the nerve e.g. bony tunnels, spinal nerve exit foramina

Treatments

  • Physical therapy (physiotherapy) may be appropriate after an injury, but may be difficult due the presence of pain and sensitivity. A multi-disciplinary approach should be tried combining pain management inputs from different specialities.
  • Topical agents like capsaicin used regularly 4 times day may help.Qutenza 179 mg (8%) applied topically once every 3 months has also beeen found to be helpful. Lignocaine pain relief patches are also useful (Versatis released January 2007).
  • Oral Medications - see Anti-convulsants, Anti-depressants, Anti-arrhythmics, Multiple action drugs e.g. tramadol (Zamadol), tapentadol (Palexia) block morphine, noradrenaline and serotonin receptors
  • Scar desensitisation injections repeated 3 - 5 times with dilute local anaesthetic and steroid can reduce scar hypersensitivity.
  • Peripheral Nerve blocks on several occasions may help when a peripheral nerve trunk is involved and is easily accessible. Permanent blocks with Phenol, Cryotherapy, Radiofrequency lesions, are not advised as they may help initially, but may cause deafferentation pain afterwards, which is worse than the original problem.
  • Sympathetic Nerve Blocks (LA only) may be useful. Permanent Phenol blocks are not advised.
  • Intravenous Lignocaine Infusions are useful for some patients.
  • Surgery may appropriate to decompress the nerve, and remove suture materials known to increase the risk of scar pain e.g. nylon.
Scars
  • All scars whether surgical or traumatic are capable of producing neuralgic pain in the skin afterwards.
  • The reason for this is not completely understood, but it seems that in some people superficial skin nerves become entrapped in scar tissue during the healing process.
  • From clinical experience this seems much more common after a wound infection, or when there was delayed healing for some reason. Continuing pain during the healing phase may cause sensitisation of the dorsal horn in the spinal cord.
  • See Introduction for clinical findings and treatments. Investigation with an EMG is not appropriate for scar pain.
Neck, Armpit, and Upper Arm

After Neck / Laryngeal Surgery

  • The Superficial Cervical Plexus in the side of the neck can be injured by:-
    • Surgery (Laryngectomy) and Radiotherapy to treat cancer of the larynx (voice box).
    • Infections (Tuberculosis) affecting the lymph glands in the neck.
  • The plexus has 4 sensory branches supplying areas of skin, and one branch supplying a muscle:-
    • Anterior Cervical Nerve - front of the throat.
    • Supraclavicular Nerve  - overlying the collar bone.
    • Greater Auricular Nerve - behind the ear.
    • Lesser Occipital Nerve - behind the ear towards the back of the head.
    • Accessory Nerve - motor supply to the trapezius muscle ("coat hanger" muscle in the back of the neck)
  • Neuralgic symptoms may be experienced in any or all of the sensory branches depending on the level of the nerve injury.
  • Superficial Cervical Nerve blocks on several occasions may help.
  • See Introduction for clinical findings and treatments.

Brachial Plexopathy

  • The Brachial Plexus (main nerve bundle to the upper limb) can be affected by :-
    • Metastatic breast cancer and radiotherapy to the axilla (armpit).
    • Traction injuries to the upper limb (serious road traffic accidents).
    • Incorrect arm positioning during surgery. The plexus may be injured when the arm is taken beyond 90 degrees of abduction (outward movement away from the body) for prolonged periods. The head of the humerus (arm bone) can indent the plexus and also cut off blood supply to it when the 90 degree rule is not observed.
  • Neuralgic pain radiates to all or part of the upper limb in the C5, C6, C7, C8, T1 dermatomes depending on the part of the plexus affected. Weakness and numbness in the arm and hand may also be present.
  • Brachial plexus nerve blocks on several occasions may be useful.
  • See Introduction for clinical findings and treatments.

Intercostobrachial Neuralgia

  • The intercostobrachial nerve can be injured during surgery to the armpit (axilla). It most frequently is associated with breast cancer surgery where lymph glands have been removed from the axilla.
  • The nerve has a T1/T2 Spinal Nerve Origin , and therefore symptoms radiate down the inside of the arm to the elbow (T1), and also around the upper chest (T2).
  • X-ray guided 1st and 2nd rib Intercostal Nerve Blocks can be helpful.
  • See Introduction for clinical findings and treatments.

Radial Neuralgia

  • The radial nerve runs in the spiral groove on the back of the arm bone (humerus). Injury to the nerve causes a wrist drop and numbness on the back of the forearm and hand.
  • Injury can be caused by :-
    • Direct pressure
      • Drunk's Palsy can occur when falling asleep with the arm draped across the back of a chair whilst intoxicated.
      • Poor positioning and padding during surgery.
    • Oxygen starvation - excessive tourniquet times during surgery (> 2hours).
  • Nerve Blocks are not advised at the level of the spiral groove due to the risk of injuring the nerve further.
  • See Introduction for clinical findings and treatments.
Elbow and Forearm

Dorsal Radial Branch Neuralgia

  • The Dorsal Branch of the radial nerve is a purely sensory nerve that runs around the outside edge of the forearm to supply sensation to back of the hand, fingers and thumb.
  • It can be injured after a broken wrist (Colles fracture) where there has been a lot of bruising inside the forearm plaster. As the pressure rises inside the forearm plaster, the nerve is injure due to lack of blood supply and oxygen. The nerve can also be injured by direct blows to the outside of the forearm.
  • Symptoms radiate from the lower forearm into the back of the hand and fingers. This may mimic Reflex Sympathetic Dystrophy.
  • Dorsal Radial Branch nerve blocks may help.
  • See Introduction for clinical findings and treatments.

Ulnar Neuritis

  • The ulnar nerve can be injured by direct blows to the elbow.
  • It is also vulnerable to direct pressure during surgery. This can be prevented by proper positioning and padding.
  • Ulnar Nerve Blocks may be useful. Great care is required not to injure the nerve with the needle.
  • See Introduction for clinical findings and treatments.

Wrist and Fingers

Injuries to the wrist can affect the Median Nerve and Ulnar Nerves.

Digital Neuralgia can follow an injury to the fingers.

  • Each finger has four digital nerves. Two larger nerves supply the palmar surface, and two smaller ones supply the back of the finger.
  • Digital Nerve Blocks may be useful.
  • See Introduction for clinical findings and treatments.
Chest

After Thoracotomy

  • During a thoracotomy (opening made between the ribs to allow chest surgery), the 5th, 6th, or 7th intercostal nerves can be affected either by removal of a rib, or by direct injury caused by surgical instruments. Neuroma formation may occur at the point that the nerve is severed.
  • This can cause 5th, 6th, 7th Intercostal Neuralgia with symptoms radiating around the chest wall to the front.
  • X-ray guided Intercostal Nerve Blocks repeated on several occasions can be useful. Also targeting the neuroma at the end of the cut rib and nerve can also be helpful.
  • Musculo-skeletal pain is common after such a big operation. Spinal Manipulation and paravertebral trigger point injections may also be useful.
  • See Introduction for clinical findings and treatments.
Abdomen

After Nephrectomy

  • During nephrectomy (kidney removal) the 11th or 12th intercostal nerves can be affected either by removal of the 11th or 12th ribs, or by direct injury by surgical instruments. Neuroma formation may occur at the point that the nerve is severed.
  • This can cause 11th or 12th Intercostal Neuralgia with referred pain coming around the chest to the lower abdomen.
  • X-ray guided Intercostal Nerve Blocks repeated on several occasions can be useful. Also targeting the neuroma at the end of the cut rib and nerve can also be helpful.
  • Musculo-skeletal pain is common after such a big operation. Spinal Manipulation and paravertebral trigger point injections may also be useful.
  • See Introduction for clinical findings and treatments.
Buttock

Sciatic Neuralgia

  • Anatomy
  • Trauma to the buttock (gluteal) region can injure the sciatic nerve causing a type of nerve pain down the leg resembling sciatica.
  • Trauma to the area can be due to :-
    • Stab wounds e.g. knife attack to the buttock / posterior thigh
    • Blunt trauma e.g. road traffic accident
    • Compression injuries e.g. falling asleep whilst under the influence of drugs and / or alcohol
    • Traction injuries e.g. excessive stretching of the sciatic nerve during a total hip replacement
  • See Introduction for clinical findings and treatments.
  • The chance of partial / total recovery following sciatic nerve trauma depends on whether the outer sheath of the nerve is intact.
  • When the nerve sheath has been transected or damaged (knife injuries and blunt trauma), there is no chance of the nerve reconnecting with the area it originally supplied. There is also a higher chance of a sciatic neuroma forming at the site of the injury.
  • When the nerve sheath is intact (compression and traction injuries), there is a good chance that the nerve will reconnect with the area it originaly supllied. There is also a lower risk of sciatic neuroma formation.
  • As injured nerves re-grow at the rate 2 mm / week, it can be many months before nerve reconnection is completed and the final extent of the injury known.
Groin and Thigh

After Hernia Repair

  • Anatomy
  • Surgical hernia repairs (herniorraphy) can sometimes result in injury to the iliohypogastric, ilioinguinal and genitofemoral nerves. The iliohypogastric nerve can also be injured by lower abdominal incisions e.g. after hysterectomy.
  • This can cause neuralgic pain in the groin and inner thigh in the T12 and L1 dermatomes .
  • Nerve entrapment in the groin seems to be more common after a mesh type repair, possibly due to more fibrous tissue formation.
  • The pubic bone can be quite tender after a hernia surgery if the surgeon placed a stitch through the outer layers of the pubic bone to strengthen the repair. This is called pubic osteitis (inflammation of the periosteal layers of the pubic bone).
  • Iliohypogastric and genitofemoral nerve blocks on several occasions can be useful. Infiltrating around the pubic tubercle is also useful when pubic osteitis is suspected.
  • See Introduction for clinical findings and treatments.

Femoral Neuralgia

  • Anatomy
  • The femoral nerve is the main nerve to the front of the thigh, knee, and inner shin to the ankle and supplies the L2, L3, L4 dermatomes .
  • It travels through the groin with the femoral artery half way between the pubic and hip bone.
  • Neuralgic symptoms often radiate from the groin into the front of the thigh and inner shin as far as the ankle. Weakness of the quadriceps muscles may cause giving way of the knee joint.
  • Causes of femoral neuralgia include:-
    • Direct injuries e.g. a Butcher's meat cleaver slips cutting through the groin region.
    • After surgery in the groin region associated with post operative bleeding, haematoma formation, and nerve compression. This may follow:-
      • Femoral angiography for heart and peripheral vascular disease
      • Vascular graft surgery for poor circulation in the legs.
      • Varicose vein surgery.
  • Femoral nerve blocks on several occasions may help.
  • See Introduction for clinical findings and treatments.
Knee and Lower Leg

After Arthroscopy

  • Arthroscopy (telescope examination) of the knee joint can injure the medial (inside) and lateral (outside) patellar nerves in front of the knee just below the knee cap.  
  • The arthroscope accidentally bruises the nerves as it passes through the skin tissues to enter the knee joint.
  • Afterwards neuralgic pain and sensitivity is often felt around the arthroscopy incisions and for several inches below the knee on either side of the upper shin bone.
  • There may also be over activity of the sympathetic nervous system in the area. This has been incorrectly labeled by orthopaedic surgeons as Reflex Sympathetic Dystrophy of the Knee.
  • Full thickness scar infiltrations on several occasions can be very useful.
  • See Introduction for clinical findings and treatments.

After Varicose Vein Surgery

  • Varicose vein surgery can be associated with injury to the following nerves:-
    • Saphenous Nerve at the upper tibial level (shin bone) just below the inside knee. Symptoms radiate from the knee down the inner shin to the level of the ankle.
    • Sural Nerve at the outside ankle joint. Symptoms radiate from the ankle to the foot.
    • Common Peroneal Nerve deep in the space behind the knee joint (rarely).
  • Appropriate nerve blocks may help.
  • See Introduction for clinical findings and treatments.
Ankle and Foot

Ankle and foot injuries may affect any of the following nerves:-

  • Anatomy
  • Posterior tibial nerve behind the inside ankle bone.
  • Saphenous nerve in front of the inside ankle bone.
  • Superficial peroneal nerve in front of the ankle.
  • Deep peroneal nerve in front of the ankle.
  • Sural nerve behind the outside ankle bone.

See Nerve entrapment (foot) for more information. See Introduction for clinical findings and treatments.

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