Weakness [of muscles]

Nota:

• focal or generalised?  do careful clin assess, complement with brain/spinal imaging unilat limb weak? eval URGENTLY ? STROKE??

1. myelopathy, radiculopathy or peripheral neuropathy
   1. periph nerve lesions
      1. LMN weak
      2. may result from
         1. generalised disease of PNS = periph neuropathy (glove and stocking
         2. lesions affecting a plexus = plexopathy
         3. spinal root = radiculopathy
         4. single N = mononeuropathy
2. osteoarthritis
3. rheumatoid arthritis
4. thyroid disorders
5. stroke
   1. most common cause unilat limb weak
   2. sudden onset (typically) of WEAK (arm, leg, face); unilat
   3. symps >3hrs, often don't resolve
   4. initial flaccid weak -> UMN weakness days later
   5. assoc
      1. signs of cortical dysfunct (eg vis field dfect, dyschasia, dyspraxia, neglect, sensory or visual inattention)
      2. or other sensory vis or coord probs
      3. signs/symps UNILAT unelss brainstem (but watch out for dbl strokes)
6. TIA (transient ischemic attack)
   1. temp, focal, ischemic insults
   2. symp/signs <10mins
   3. comparable to stroke but resolve entirely w/o perm neuro effects
   4. do not cause LOC (except very rare)
7. space occupying lesions
   1. eg tumor, abscess, chronic subdural hematoma
   2. onset gradual, progressive
   3. symp/signs mimic stroke
   4. maybe increased ICP feats (headache wosre when lie or cough)
      1. severe headache
      2. decreased GCS
      3. VI nerve palsy or unilat pupil dilat
      4. vomit
      5. bradycardia/systolic hypertension
      6. papilledema
8. spinal cord lesions
   1. transverse
      1. bilat UMN weakness (para/tetraparesis) with loss of ALL SENS below spin cord + disturbance of sphincter funct
   2. unilat lesions
      1. ipsilat UMN (Brown-Sequard)
         1. + loss of proprio below cord lvl
         2. + contralat loss of pain and temp
   3. causes
      1. compressive lesions
         1. eg prolapse disc, trauma, vertebral mets, intrinsic pathology (eg glioma, spinal infarct, Blz defic)
         2. circumferential pain across OR sensory loss belwo a thoracic or lumbar dermatome suggest cord compression (but is not always present)
            1. lvl should correlate with neuro exam of lower limbs
         3. saddle anesthesia, bilat leg pain, urin retent and decreased anal tone suggest CAUDA EQUINA syndrome
9. motor neurone disease
   1. chronic, degen
   2. presents: graudal + progressive weakness, combo of UMN + LMN signs
   3. may be bulbar involve but SENSORY feats absent
10. other
    1. encephalitis

       Nota:

       • limb weak as part of lots of CNS symps confusion, seiz, alt consc
    2. multiple sclerosis

       Nota:

       • present w/any pattern of UMN limb weak (though PARAPARESIS 2ndry to transverse myelitis is most typical)
    3. focal seizure

       Nota:

       • transient focal limb weak (Todd's paresis)
    4. migraine

       Nota:

       • occ cause limb weak (hemiplegic migraine) but is diag of exclusion
    5. myasthenia gravis

       Nota:

       • causes fatiguability of limb muscs
    6. generalised musc weak may be from

       Nota:

       • congen/inflamm myopathy metabolic disturb drugs/toxins acute illness in frail/elderly
11. MRC scale

    Nota:

    • 1 no more 2 flicker of contract only 3 move possible when grav removed no resist 4 OK against grav but NOT completely against full resist 5 normal against full resist