Key distinguishing features of the most common diagnoses
|Anxiety||CT Syndrome||Sciatica||Diabetes||Cervical Spondylosis|
|Worse at Night||No||Yes||No||Possible||Possible|
Likely:Urinalysis, blood sugar or HbA1c.
Possible:FBC, LFT, γGT, U&E, serum calcium, B12 and folate, TFT, serum electrophoresis, nerve conduction studies.
Small Print:Autoimmune screen, cervical spine X-ray, secondary care investigations (MRI/ CT scan, lumbar puncture, carotid imaging, angiography, myelography).
- Urinalysis: To pick up glycosuria in undiagnosed diabetes.
- Blood sugar or HbA1c: To confirm diabetes.
- FBC: To look for macrocytosis (sign of alcohol excess or B12/folate deficiency). May be anaemia of chronic illness or malignancy.
- LFT and γGT if alcoholic neuropathy suspected.
- Metabolic screen (including U&E, calcium, LFT, B12 and folate).
- TFT: Hypothyroidism can cause a polyneuropathy or precipitate carpal tunnel syndrome.
- Serum electrophoresis: To exclude myeloma.
- Autoimmune screen: To help diagnose a connective tissue disorder.
- Nerve conduction studies: To confirm a diagnosis of nerve compression prior to surgical treatment.
- X-ray cervical spine: Confirms clinical diagnosis of cervical spondylosis, but not really helpful as positive findings common and don’t correlate well with symptoms, and the investigation is unlikely to alter the management.
- Secondary care investigations might include: Lumbar puncture (MS, Guillain–Barré syndrome), carotid imaging (TIA), CT or MRI scan (spinal pathology or compression, MS, cerebral tumour, syringomyelia), angiography (vascular causes), myelography (cord compression).
- Intermittent perioral paraesthesiae are pathognomic of hyperventilation.
- Use a logical approach: A careful history will often reveal the likely underlying problem. For example: Well-demarcated area in anatomically explicable distribution – peripheral nerve entrapment; larger area, one limb – root compression; whole side of body – cerebral lesion; hands and feet – peripheral neuropathy; legs alone – possible cord lesion.
- Wasting of the thenar eminence suggests significant CT syndrome which will require decompression.
- Remember to tell women taking the combined oral contraceptive who develop migraine with focal symptoms to use an alternative method of contraception.
- Sudden and progressive bilateral leg symptoms with sphincter disturbance suggest cord compression – admit immediately.
- Intermittent paraesthesiae in varying distributions – especially with other features, such as vertigo or optic neuritis – suggest MS.
- A patient with a TIA within the preceding week should be given aspirin 300 mg immediately and referred for a specialist assessment to take place within 24 hours.
- The borders of sensory loss in functional neurological disorder are often sharply demarcated and do not correspond to an anatomical pattern.
- Constant, progressive paraesthesiae, especially with other neurological symptoms or signs, suggest significant pathology. Refer urgently.