Peripheral Neuropathies

• Different types of peripheral neuropathies:

  • Polyneuropathies
  • Radiculopathies
  • Mononeuropathies
• Major causes of peripheral neuropathy:

  • Trauma - usually due to compression
  • Metabolic - diabetes and hypothyroidism
  • Infective
  • Inflammatory
  • Autoimmune - Guilliain-Barre syndrome
  • Malignancy
  • Vitamin deficiencies - B12 and folate
  • Alcoholism and exposure to toxins
• Polyneuropathies often are length-dependent, meaning more distal nerves are affected first. Polyneuropathy is a broad term that refers to damage to multiple peripheral nerves. It is classically distally located with a glove and stocking distribution. Examples of polyneuropathy:

  • Diabetic neuropathy
  • Guillian-Barre syndrome
• High blood glucose in the case of diabetes, cause chemical changes in nerves and impairs the nerves ability to transmit signals. Over time the high blood glucose also causes damage the capillaries that supply the nerves.
• Bell's Palsy is an acute mononeuropathy that involves the facial nerve (7th cranial nerve)
• Bell's Palsy begins suddenly and worsens over 48 hours, typical symptoms:

  • Loss of sensation
  • Paralysis of facial muscles - without forehead sparing
  • Tearing and drooling
  • Hypersensitive to sound
• If the Bell's palsy has started within 72 hours then it can be treated within prednisolone

  Patients also require lubricating eye drops

  If they develop pain in the eye, the need an ophthalmology review for exposure keratopathy. The eye can be taped closed at night.
• Radiculopathy is an injury to the nerve root as it leaves the spine - sciatica is an example of a radiculopathy

  Radiculopathy causes sensory deficit with a dermatomal pattern
• Carpal tunnel syndrome is caused by compression of the medial nerve as it travels through the flexor retinaculum ligament

  Swelling from repetitive strain and narrowing of the tunnel
• Causes of carpal tunnel syndrome:

  • Mostly idiopathic
  • Repetitive strain
  • Acromegaly - commonly bilateral
  • Pregnancy
• Presentation of carpal tunnel syndrome:

  • Causes sensory symptoms on the palm, thumb, index finger, middle finger and lateral half of ring finger
  • Often worse at night
  • Motor symptoms affect the thenar muscles - can cause wasting
• Tests for carpal tunnel:

  • Phalen's test - patient puts back of hands together in front of them which triggers sensory symptoms
  • Tinsel's test - tapping over the median nerve triggers sensory symptoms
  • Primary investigation - nerve conduction studies
• Management of carpal tunnel:

  • Rest and altered activities
  • Wrist splits at night
  • Steroid injections
  • Decompression surgery - flexor retinaculum is cut
• Cubital tunnel syndrome is caused by compression of the ulnar nerve as it passes through the cubital tunnel on the inside of the elbow

  Also known as golfers elbow
• Causes of cubital tunnel syndrome:

  • Repetitive use of elbow
  • Arthritis
  • Bone spurs
  • Previous fracture/dislocation
  • Most cases are idiopathic
• Symptoms of cubital tunnel:

  • Numbness and tingling in the 5th digit and lateral part of the ring finger
  • Weak grip and clumsiness due to muscle weakness
  • Aching pain on the inside of the elbow
• Diagnosis of cubital tunnel:

  • Nerve conduction test
  • EMG - test forearm muscles controlled by the ulnar nerve
  • XR - check for arthritis and bone spurs
• Management of cubital tunnel syndrome:

  • Resting and altered activity
  • Splint at night
  • NSAIDs
  • Nerve gliding exercises
  • Surgery to cut the cubital tunnel
• Treatment of Bell's Palsy (if within 72 hours) is with prednisolone:

  • 50mg for 10 days or
  • 60mg for 5 days followed by a 5-day reducing regime, dropping the dose by 10mg per day
• The sciatic nerve originates from L4-S3 spinal nerves
• Radial mononeuropathy:

  • Classic presentation is an acute wrist drop
  • Tennis elbow = inflamed tendons of extensor muscles against the lateral epicondyle - compressed radial nerve
  • Sensory loss over the dorsum of the hand
  • Weakness in finger extension