Spinal Nerve Root Flashcards
Segmental Organization
- 8 cervical (C1-C8).
- 12 thoracic (T1-T12).
- 5 lumbar (L1-L5).
- 5 sacral (S1-S5).
- 1 coccygeal (Co).
- Growth of bones after cord stops = conus medullaris, ~ L1-L2.
- Cauda equina.
- Filum terminal.
Spinal Cord
Organization
- Motor & sensory roots (L & R) arise from each segment except C1.
- C1 has no sensory roots, ONLY motor.
- Cervical enlargement (C5-T1).
- Lumbar enlargement (L1-S3).
- Mixed spinal nerves from each segment (*except?)
Vertebae
Vertebrae
- Provide mechanical support.
- Anteriorly; vertebral body.
- Posteriorly; superior & inferior articular processes.
- Protection.
- Spinal cord through the vertebral canal surrounded by meninges.
Vertebrae
Vertebrae
Vertebrae
Spinal Canal
- As dura exits skull, outer layer becomes 1 with periosteum- indistinguishable.
- Layer of epidural fat between dura & periosteum in spinal canal (landmark.)
- Batson’s venous plexus; valveless.
- Network connecting deep pelvic veins draining bladder, prostate & rectum to internal vertebral venous plexus.
- *Mets.
Spinal Canal
Disc Herniations
- N.R. involved usually corresponds to lower of 2 adjacent vertebrae.
- C-spine PLL thick & N.R.s exit horizontally; herniates laterally.
Disc Herniations
•L & S-spine N.R.s travel down & into lateral recesses of canal of canal; closest to disc for posterolateral herniation.
Disc Herniations
•Far lateral disc herniation reach N.R. exiting at that level = impingement of next higher N.R.
Dermatomes
- Sensory distribution on skin by a N.R.
- A map but references vary some.
- Face = trigeminal nerve.
- Rest of head mostly C2 (greater & lesser occipital nerves.)
- Torso; nipples T4, umbilicus T10.
Dermatomes
Dermatomes
Dermatomes
Myotomes
•Muscles innervated by a single nerve root.
Myotomes
Summary of Peripheral Nerves, muscles, Nerve Roos in the Upper and Lower Extremities
Summary of Peripheral Nerves, muscles, Nerve Roos in the Upper and Lower Extremities
Summary of Peripheral Nerves, muscles, Nerve Roos in the Upper and Lower Extremities
Summary of Peripheral Nerves, muscles, Nerve Roos in the Upper and Lower Extremities
Summary of Peripheral Nerves, muscles, Nerve Roos in the Upper and Lower Extremities
Disorders of Nerve, NMJ, & Muscle
- Peripheral sensory or motor patterns/deficits.
- LMN lesions.
- Atrophy, fasciculations, decreased tone, & hyporeflexia.
Disorders of Nerve, NMJ, & Muscle
- Causes:
- Mechanical.
- Toxic.
- Metabolic.
- Infectious.
- Autoimmune.
- Inflammatory.
- Degenerative.
Common Neuropathies
- A nerve disorder.
- Axon, myelin or both involved.
- Large diameter, small diameter, or both involved.
- Usually both motor and sensory involved.
- Reversible or permanent.
- Radiculopathy involved spinal nerve root.
Important Causes-Neuropathies
- Diabetes.
- Mechanical disorders.
- Infectious disease; HIV, CMV, Lyme disease, varicella-zoster virus, hep-B.
- Toxins.
- Malnutrition.
- Immune disorders; Guillain-Barre, Charcot-Marie-Tooth disease…
Diabetic Neuropathy
- Compromised microvascular blood supply to peripheral nerves.
- Distal symmetrical polyneuropathy.
- Stocking glove distribution of sensory loss.
- Mononeuropathy.
- Cranial or spinal nerves but CNIII, femoral & sciatic commonly.
- Sudden onset, maybe painful paresthesia.
Partial or complete recovery
Mechanical Causes of Nerve Injury
- Extrinsic compression, traction, laceration or entrapment.
- Intrinsic compression by bone, or CT.
- Neuropraxia; temporary impairment of NCV.
- Wallerian degeneration; severe injury & distal death.
- Axonal regeneration; 1mm/day.
- RSD; regional pain syndrome following injury without specific nerve damage.
- Causalgia; damage to specific nerve.
Long Term Complications
- Incomplete or aberrant reinnervation.
- RSD (reflex sympathetic Dystropy Syndrome); regional pain syndrome following injury without specific nerve damage.
- Causalgia; damage to specific nerve.
Local, intense burning pain with edema, sweating, & changed skin blood supply
Guillain-Barre Syndrome
Acute Inflammatory Demyelinating Polyneuropathy (AIDP)
- Immune-mediated demyelination of PNS.
- 1-2 weeks post viral infection.
- Camphylobacteri jejuni enteritis, HIV…
- Progressive weakness, areflexia, tingling paresthesias of hands, feet with more severe motor involvement.
- Wort 1-3 weeks after onset; recovery = months.
Dx: symptomatology & elevated CSF proteins wo increased WBC s & (+)EMG for demyelination
Disorders of NMJ
- Motor weakness without sensory deficits.
- Causes:
- M.G.
- NM blocking agents & other drugs.
- Lambert-Eaton myasthenic syndrome.
- Botulism.
Myasthenia Gravis
- Immune-mediated disorder.
- Postsynaptic nicotinic acetylcholine receptor antibodies.
- Sometimes runs with other autoimmune dys(fx).
- Hypothyroidism.
- SLE.
- R.A.
- Vitiligo.
Myasthenia Gravis
- Onset:
- 20-30y.o.; females
- 60-70y.o.;males.
- Generalized symmetrical weakness, proximal limb, neck, diaphragm, eye muscles, & bulbar muscles (CN IX-XII): facial weakness, nasal voice & dysphagia.
- **WEAKNESS BECOMES MORE SEVERE WITH REPEATED USE.
IF JUST EYES=
OCULAR MYASTHENIA
(15%).
Myasthenia Gravis
- Diagnosis:
- Clinical features.
- Ice pack test (ptosis.)
- Repetitive nerve stimulation.
- Measurement of antibodies.
- Tensilon test (old-2008 DQ)
- Neostigmine.
CMAP=characteristic decrement in amplitude
Dermato- & Polymyositis
- Immune-mediated inflammatory myopathies.
- Increased blood CPK.
- (+) EMG for myopathy.
- Dermatomyositis: characteristic violet-colored skin rash on extensor surface knuckles & other joints.
- Duchenne M.D. most common form M.D>
- X-linked inheritance
- Male children.
- Progressive proximal weakness.
Back Pain
- One of the most common causes to seek medical attention.
- Diverse causes.
- Importance of careful Hx & P.E.
- NMS causes are most common.
- > 50… neoplasm?
- Never neglect bowel, bladder, & sexual fx.
Differential Diagnosis of Back Pain
Clarifying Definitions for Degenerative Disorders of the Spine
Disc Herniation
- Most common
- C5-C6, C6-C7.
- L4-5, L5-S1
- L/S are 2-3 x more common than cervical disc herniations.
- Osteophyte formation.
- Spinal stenosis.
- >>>chronic injury to cord.
Orthopedics
- SLR
- (+)=10-60 degrees with reproduction of radiculopathy.
- Crossed SLR
- 90% (+) for L/S N.R. compression.
- Valsalva’s maneuver.
- Percussion of spine.
- (+)Metastatic disease, epidural abscess, osteomyelitis, & other bone disorders.
Straight Leg Raise
Radiculopathy
- Stenosis; narrowing of the spinal canal; congenital or degenerative.
- Lumbar stenosis.
- Neurogenic claudication.
- Bilateral leg pain & weakness with ambulation.
- Cervical stenosis.
- Radicular signs.
- Long tract signs.
- Trauma; compression, traction, avulsion.
- Diabetic neuropathy.
- Epidural mets; usually to vertebral body but can extend laterally & compress N.R.
Radiculopathy
- Many causes of neuropathies have preference for N.R. so can be a radiculopathy.
- Guillain-Barre syndrome.
- Varicella-zoster virus in DRG > herpes zoster=shingles.
- Post herpetic neuralgia or pain syndrome.
- Lyme disease.
- CMV polyradiculopathy in patients with HIV.
- HIV (milder than CMV)
- Tumors.
- Schwannomas.
- Neurofibromas.
Three important Nerve Root in the Arm
Dermatomes of the Arm
Three important Nerve Roots in the Leg
Dermatomes of the Leg
Cauda Equina Syndrome
- Impaired fx of multiple N.R.s below L1 or L2.
- If deficit at S2 or lower – maybe not see L.E. motor weakness.
- S2-S5 sensory loss = saddle anesthesia.
- S2, S3, S4 = distended atonic bladder, urinary retention, incontinence, constipation, decreased rectal tone, loss of erections. (S2,3,4 keeps the Ps off the floor.)
- Central disc, epidural mets, schwannoma, meningioma, neoplastic meningitis, trauma, epidural abscess, arachnioditis, CMV polyradiculitis.
Surgery
- Usually disc herniation resolves without surgery.
- Surgical emergency:
- Cauda equina syndrome.
- Progressive or severe motor deficit.
- Intolerable, medically intractable pain.
- Conservative care first 1-3 months.
Common Surgical Approaches
Posterior approach:
- Laminectomy
- Discectomy.
- Foraminotomy.
- Hardware if necessary.
Anterior approach to C-spine:
- Discectomy.
- Fusion (bone graft.)
- Also for T-spine discs (rare.)
