Numbness and Paraesthesiae
Differential Diagnosis
Common Diagnoses
- Anxiety with Hyperventilation
- Carpal Tunnel (CT) Syndrome
- Sciatica
- Diabetic Neuropathy
- Cervical Spondylosis
Occasional Diagnoses
- Multiple Sclerosis and Dorsal Myelitis
- Peripheral Polyneuropathy (Especially Alcohol; Also Vitamin B12 and Folate Deficiency, Iatrogenic, Metabolic, Connective Tissue Disorder, Malignancy and Rare Causes Such as Guillain–Barré, Leprosy)
- Stroke and TIA
- Trauma/Compression Involving a Peripheral Nerve or Spinal Cord
- Migraine with Focal Neurological Signs
Rare Diagnoses
- Intramedullary Spinal Cord Tumour
- Syringomyelia
- Trauma, Brain Tumour and Epilepsy Affecting Sensory Cortex
- Functional Neurological Disorder
- Vascular: Ischaemic Heart Disease, Peripheral Vascular Disease
Ready Reckoner
Key distinguishing features of the most common diagnoses
| Anxiety | CT Syndrome | Sciatica | Diabetes | Cervical Spondylosis | |
|---|---|---|---|---|---|
| Associated Dizziness | Yes | No | No | No | No |
| Episodic | Yes | Possible | Possible | Possible | Possible |
| Associated Pain | No | Yes | Yes | Possible | Yes |
| Worse at Night | No | Yes | No | Possible | Possible |
| Associated Weakness | No | Possible | Possible | No | Possible |
Possible Investigations
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).
Top Tips
- 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.
Red Flags
- 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.