12.11.06 Teaching notes

Radiology - Haemorrhage

• • Intra-axial

    • i.e. Parenchymal

  • Extra-axial

    • Extradural

      • Usually from middle meningeal artery

      • Bi-concave

        • Lens shape

      • Never crosses suture lines

      • Strips dura away

      • Check for a fracture!

    • Subdural

      • From bridging veins

      • Crosses sutures

      • Tracks dural reflections - Look for "blood lines" - high intensity lines

        • Falx cerebri

        • Tentorium cerebelli

      • Crescent shape

      • Common in older people

        • Contraction => More subdural space => Longer bridging veins

    • Subarachnoid

      • From arteries

      • Basal cisterns highlighted

      • Sulci, sylvian fissure highlighted

Peripheral neuropathies

• • Mononeuritis multiplex

    • Ssimultaneous or sequential involvement of individual noncontiguous nerve trunks, either partially or completely

    • Evolves over days to years

    • Typically presents with acute or subacute loss of sensory and motor function of individual nerves

    • The pattern of involvement is asymmetric

  • Mononeuropathy

  • Peripheral polyneuropathy

    • Sensory

    • Motor

    • Sensory-motor polyneuropathy

Median nerve

• • Thenar muscles

    • Opponens policis

      • Make a ring between thumb + little finger

    • Abductor policis brevis

      • Lift up + resist

    • Flexor policis brevis

      • Flex over palm + resist

  • Anterior interosseous nerve

    • Supplies terminal flexors of thumb + index finger

      • CRUCIAL for writing etc.

    • Isolate joint, flex + resist

Ulnar nerve

• • 1st dorsal interosseous

    • 1st thing to go => Check muscle bulk!

  • Forearm flexors

  • ALL the interossei

    • Hold piece of paper between fingers (both of you)

    • Pull apart

  • Damage:

    • Leaning on your elbow (protected only by skin)

    • Supracondylar fracture

Radial nerve

• • Extensors

    • HARD-CORE - Should not ever be able to overcome

  • => Posterior interosseous nerve => Finger extensors

Leg stuff

• • Meralgia paresthetica

  • Compression of lateral cutaneous femoral nerve of thigh

    • • => numbness or pain in the outer thigh

• • • Caused by entrapment or compression where it passes between the ilium and the inguinal ligament near the attachment at the ASIS

    • Causes:

      • Weight gain (belly roll)

      • Pistol

      • Tight underwear

• • Roots

• • • L1,2,3 => Femoral

      • Check hip flexion + knee extension

      • c.f. buckling gait

    • L4,5,S1 => Sciatic

      • => Tibial nerve (posterior leg)

      • => Common peroneal nerve

        • => Superficial peroneal nerve (lateral compartment - peroneus longus and peroneus brevis)

        • => Deep peroneal nerve (anterior compartment - tibialis anterior, EHL, EDL, peroneus tertius)

• • Common peroneal nerve wraps round the fibular head => Risk of injury

Falx cerebri / Tentorium cerebelli

Notes

• • Electrophysiology parameters

    • CV - Conduction velocity

    • DML - Distal motor latency

    • SL - Sensory latency

  • Put the muscle in action; Resist the action

  • Susceptibility to neuropathy

    • Diabetes

  • Hereditary neuropathy with liability to pressure palsies

    • • Myelin deficiency due to peripheral myelin protein 22 mutation

    • Alcohol

    • Vitamin B12 deficiency

  • Median nerve entrapment in CTS occurs at the DISTAL CREASE OF THE WRIST

  • Femoral nerve runs ABOVE the inguinal ligament in 15% of people => Susceptible to injury

  • Sensory supply to the hand: