Peripheral Neuropathies 1

Question 1

Causes of mononeuropathy

Answer 1

• Entrapment
• Multifocal Demyelination (e.g. Lewis Sumner syndrome)
• Ischemic injury
• Trauma

Question 2

Nerve injury categorization

Answer 2

• Neuronal degeneration
• Wallerian degeneration
• Axonal degeneration
• Segmental demyelination

Question 3

Common compressive neuropathies

Answer 3

Question 4

Causes of polyneuropathy

Answer 4

Question 5

Neuropathies with facial nerve involvement

Answer 5

+ Ramsay Hunt syndrome

Question 6

Neuropathies with predominantly motor manifestations

Answer 6

Question 7

Polyneuropathies with predominantly upper limb motor involvement

Answer 7

Question 8

Neuropathies with autonomic nervous system involvement

Answer 8

Question 9

Small fiber neuropathies

Answer 9

Question 10

Sensory ataxic neuropathies

Answer 10

Question 11

Approach to evaluation of peripheral neuropathies

Answer 11

Question 12

Neuropathies associated with serum autoantibodies

Answer 12

+ Nf 155,140,186
+ CNN1, CASPR1

Question 13

Diseases in which nerve biopsy can help in diagnosis

Answer 13

• Vasculitis
• Amyloidosis
• Sarcoidosis
• atypical CIDP
• giant axonal neuropathy
• leprosy

Question 14

Oculomotor nerve: Symptoms in 1) extrinsic compression 2) nerve ischemia (explain)

Answer 14

1) Isolated mydriasis
2) “pupil-sparing” third nerve palsy

The parasympathetic fibers travel in the periphery of the nerve

Question 15

Oculomotor nerve palsy: Causes

Answer 15

• Trauma (fracture to the supraorbital fissure)
• Posterior communicating artery aneurysm
• Herniation of the uncus of the temporal lobe due to increased intracranial pressure
• Ischemia
• Meningitis
• Syphilis
• Herpes zoster
• Tumor
• Demyelination

Question 16

Oculomotor nerve palsy: Differential diagnosis

Answer 16

• Brainstem infarction
• Myasthenia Gravis
• Graves opthalmopathy
• Horner syndrome
• Congenital ptosis
• Congenital anisocoria (or any other anisocoria in isolated mydriasis)

Question 17

Evaluation of non-isolated third nerve palsy

Answer 17

Third nerve palsies that are accompanied by other neurologic deficits, orbital signs, or meningismus require an evaluation that usually includes neuroimaging.
A lumbar puncture may also be required to evaluate for possible infectious, inflammatory, or carcinomatous meningitis.

Question 18

Evaluation of isolated third nerve palsy

Answer 18

A) Complete external dysfunction with normal internal function (pupil-sparing complete third nerve palsy):
In older adults, this presentation is most commonly caused by ischemic injury. Observation alone is an appropriate diagnostic option for older patients with vascular risk factors (hypertension, diabetes).
However, contrast-enhanced brain MRI and MRA should be strongly considered in patients without vascular risk factors whose deficits progress or do not improve by 6 to 12 weeks of follow-up or in those with signs of abnormal regeneration .

• evaluation for giant cell arteritis
• LP if historical or examination features suggest an infectious, inflammatory, or neoplastic process affecting the meninges

B) Third nerve palsy with complete internal dysfunction (pupil-involved) and complete or incomplete external dysfunction:
Should be assumed to be due to aneurysmal compression until proven otherwise. Patients should undergo MRI and MRA (or CTA);
however, even if the noninvasive study is negative, a catheter angiogram should be strongly considered to exclude aneurysm.

Once aneurysm and other mass lesions have been excluded
- evaluation for giant cell arteritis
- LP if historical or examination features suggest an infectious, inflammatory, or neoplastic process affecting the meninges or in the case of persistent or progressing deficits when the cause remains unclear.

Question 19

Third nerve palsy treatment

Answer 19

Patching one eye is useful in alleviating diplopia, particularly in the short term.

Prism therapy may be employed for small, comitant, long-standing deviations. “Comitant” deviations are those in which the distance between the double images is little affected by the direction of gaze. A temporary press-on (Fresnel) prism of sufficient power to align the eyes is placed on the spectacle lens. Prisms can be ground into the spectacle lens if the patient has a stable but symptomatic deviation alleviated with prism.

Strabismus surgery may be helpful in patients who fail prism therapy. However, this surgery is difficult to perform, particularly in those with complete third nerve palsies, because multiple muscles are involved

Ptosis surgery may be necessary in some patients

Question 20

Most common cause of vertical diplopia

Answer 20

Trcohlear nerve palsy

Question 21

Clinical presentation in trochlear nerve palsy

Answer 21

Head tilt away from the affected eye
Verical diplopia that is worse with the affected eye adducted and on downgaze
In primary gaze the affected eye is vertically higher and with outward rotation

Question 22

Causes of trochlear nerve palsy

Answer 22

• Trauma (most common)
• Iscemia (diabetic)
• Demyelinating disease
• Tumor
• Lesions of the cavernous sinus

Question 23

Which nerve has the longest intracranial course and which is the only nerve with dorsal exit from the brainstem
What is the result of this

Answer 23

Trochlear nerve
Prone to trauma

Question 24

Actions of extraocular muscles

Answer 24

Question 25

Which artery aneurysm most commonly causes trochlear nerve palsy

Answer 25

Superior cerebellar artery in the subarachnoid space

Question 26

Parks-Bielschowsky three-step test for trochlear nerve palsy

Answer 26

Question 27

Trochlear nerve palsy differential diagnosis

Answer 27

1) Restrictive vertical strabismus (orbital floor fracture, orbital tumors, orbital pseudotumor, and Graves ophthalmopathy). Patients with these conditions usually have additional orbital signs, such as proptosis, chemosis, and conjunctival injection. Forced ductions (passive rotation of the eyes with ophthalmic forceps) typically confirm the restrictive nature of the ophthalmoplegia.

2) Other paretic vertical strabismus

3) Myasthenia gravis

4) Ocular tilt reaction and skew deviation (disruption of vestibulo-ocular connections)

5) Thyroid ophthalmopathy

Question 28

Trochlear nerve palsy treatment

Answer 28

Prism therapy may be employed for small, comitant, long-standing deviations.
A temporary press-on (Fresnel) prism of sufficient power to align the eyes is placed on the spectacle lens. Permanent prisms can be ground into the spectacle lens if the patient is happy with the result and the deviation fails to improve spontaneously.

Strabismus surgery may be helpful in patients who fail prism therapy.

Patching one eye will alleviate binocular diplopia and is useful for patients who are being observed or who defer prism or surgical therapy

Additional therapies may alleviate the symptoms of traumatic fourth nerve palsy while it recovers its function (ie, botulinum toxin injection in the inferior oblique muscle)

Question 29

Trigeminal neuropathy symptoms

Answer 29

• Sensory loss on one side of the face; however, patients may report loss of sensation of mucous membranes of the oral and nasal cavities.
• The corneal reflex may be absent or diminished
• Paralysis of the muscles of mastication and deviation of the jaw to the weak side
• deafness to low-pitched sounds from paralysis of the tensor tympani muscle

Question 30

Conditions affecting 1) trigeminal nucleus 2) trigeminal fascicles

Answer 30

1) Tumor, demyelinating disease, syringobulbia, or vascular disease can involve the trigeminal nucleus

2) Infection, trauma, aneurysm, and malignancy can affect the nerve fascicle

Question 31

Abducens nerve palsy causes

Answer 31

• meningitis
• compression by an enlarged, ectatic basilar artery
• hydrocephalus
• demyelinating disease
• tumor
• disease of the cavernous sinus
• Ischemia of the nerve (most commonly affects diabetic
  patients)
• Increased intracranial pressure even in the absence
  of direct compression by a mass lesion
• giant cell arteritis
• granulomatosis with polyangiitis

Question 32

Abducens nerve palsy symptoms

Answer 32

Horizontal diplopia that is worse when looking toward
the affected side

Adduction of the affected eye in primary gaze

Question 33

Abducen nerve nucelus anatomy

Answer 33

Each sixth nerve nucleus in the dorsal pons contains all of the neurons responsible for ipsilateral horizontal gaze .
These include the motor neurons for the ipsilateral lateral rectus muscle and the interneurons to the contralateral third nerve medial rectus muscle subnucleus in the midbrain.
The interneurons travel through the medial longitudinal fasciculus to the contralateral third nerve subnucleus

Question 34

Gradenigo syndrome

Answer 34

lesion of the petrous apex (κορυφή λιθοειδούς οστού)

Facial pain and involvement of the fifth cranial nerve in addition to the sixth nerve

(Uptodate ++ seventh and eighth )

Question 35

Abducen nerve palsy differential diagnosis

Answer 35

• Restrictive orbitopathy (Thyroid eye disease, Orbital floor fracture, orbital tumor, or orbital pseudotumor)
• Orbital myositis
• Myasthenia gravis
• Supranuclear disorders of gaze
• Childhood esotropia
• Spasm of the near reflex
• Sagging eye syndrome

Question 36

Tolosa - Hunt syndrome: 1) Cause 2) clinical presentation

Answer 36

1) idiopathic granulomatous inflammation of the cavernous sinus, superior orbital fissure or orbit

2) episodic orbital pain associated with paralysis of one or more of the third, fourth, and/or sixth cranial nerves, which usually resolves spontaneously but tends to relapse and remit

Patients report a constant pain behind the eye that may begin several days (up to 30 days) prior to the ophthalmoplegia

Tolosa-Hunt syndrome is typically unilateral; bilateral symptoms occur in 4 to 5 percent of cases

Involvement of cranial nerve III is reported most frequently (85 percent), followed by cranial nerve VI (70 percent), the ophthalmic division of cranial nerve V (30 percent), and cranial nerve IV (29 percent). Involvement of periarterial sympathetic fibers causes a third order Horner syndrome in approximately 20 percent of patients.

Left untreated, symptoms of Tolosa-Hunt syndrome may resolve spontaneously after an average of approximately eight weeks.

Question 37

Tolosa - Hunt syndrome: 1) Diagnosis 2) treatment

Answer 37

1) Diagnostic criteria — The specific diagnostic criteria recommended by the International Headache Society are:

● Unilateral headache, and

● Granulomatous inflammation of the cavernous sinus, superior orbital fissure or orbit, demonstrated by MRI or biopsy, and

● Paresis of one or more of the ipsilateral third, fourth, and/or sixth cranial nerves, and

● Evidence of causation demonstrated by both of the following:

• Headache has preceded oculomotor paresis by ≤2 weeks or developed with it
• Headache is ipsilateral to the granulomatous inflammation

● Symptoms not better accounted for by an alternative diagnosis

2) Glucocorticoids

Question 38

Cavernous sinus syndromes causes

Answer 38

• carotid dissection
• carotid aneurysm
• thrombophlebitis of the cavernous sinus
• fungal infection (mucor or rhizopus species)

Question 39

Facial nerve function

Answer 39

• motor division, which innervates the muscles of facial expression
• parasympathetic fibers to the lacrimal, parotid, submandibular, and sublingual glands
• taste fibers from the anterior two thirds of the tongue
• sensory fibers from the external auditory canal and pinna (πτερύγιο)

Question 40

Differential diagnosis of facial nerve palsy

Answer 40

Question 41

Bell palsy clinical presentation

Answer 41

• unilateral facial weakness and a facial droop that is most obvious around the mouth
• increased sensitivity to sound - hyperacusis (resulting from denervation of the stapedius muscle - μυς του αναβολέα)
• eye irritation on the affected side (resulting from corneal
  dryness secondary to incomplete eyelid closure)
• The corneal reflex is decreased or absent.
• There may be loss of taste over the anterior two thirds of the tongue

Question 42

Bell’s palsy incidence
When is it most common

Answer 42

1 case in 5000 people

It is more common during pregnancy especially in the third trimester and in the first postpartum week and in the elderly

Question 43

Bell’s palsy complications

Answer 43

• During the recovery period, patients may experience synkinesis, or involuntary activation of facial muscles in one region during voluntary activation in another (eg, uncontrolled, simultaneous blinking with chewing), as a result of abnormal reinnervation during recovery
• Patients with incomplete recovery may have permanent deficits ranging from a cosmetic deformity to chronic corneal desiccation (αφυδάτωση)

Question 44

Bell’s palsy temporal features

Answer 44

Onset of facial weakness in Bell’s palsy occurs over several hours, up to 72 hours.
Symptoms may worsen for days, up to three weeks, then stabilize to improve.

When symptoms occur suddenly or fail to improve at least partially by four months, alternative diagnoses should be considered

Question 45

Atypical features of Bell’s palsy

Answer 45

Features that are atypical for Bell’s palsy include:

● Atypical clinical features

*Bilateral acute facial weakness

*Additional cranial neuropathies or other neurologic signs

*Systemic signs (eg, rash, swelling, cervical adenopathy)

● Atypical temporal pattern

*Sudden onset of symptoms at maximal severity (ie, no progression)

*Insidious onset of symptoms (eg, over weeks to months)

*Continued worsening of symptoms beyond three weeks

*No improvement in symptoms within four months of onset

Question 46

Bell’s palsy differential diagnosis

Answer 46

1) Herpes zoster
(Ramsay Hunt syndrome) is diagnosed when ear pain and vesicles are found in the external meatus in the setting of a peripheral facial nerve palsy.
In addition, herpes zoster infection may occasionally occur without vesicles, a condition known as zoster sine herpete

2) Lyme disease
Facial nerve palsy is an acute neurologic manifestation and the most common cranial neuropathy associated with Lyme disease. Facial nerve palsy due to Lyme disease may be bilateral and may occur with or without meningitis. Additional findings suggestive of possible Lyme disease include erythema migrans, fatigue, headache, arthralgias, and lymphadenopathy.
Lyme disease is diagnosed by serologic testing.

3) Otitis media, mastoiditis, and cholesteatoma
Facial paralysis is a potential complication of otitis media (bacterial infection of the middle ear) and may also occur in the setting of mastoiditis or a cholesteatoma.

Severe infection with osteomyelitis of the petrous ridge of the temporal bone may cause Gradenigo syndrome, characterized as facial nerve palsy along with ipsilateral abducens (sixth) nerve palsy and retroorbital pain.

4) Guillain-Barré syndrome
Facial weakness that is typically bilateral and symmetric may occur in more than half of patients with GBS. GBS is typically identified in patients with facial palsy by symmetric progressive limb weakness, the presence of additional cranial nerve findings, and reduced deep tendon reflexes.

5) HIV infection
HIV infection rarely causes facial palsy or other mononeuropathies but may cause polyneuropathies, typically in patients with severe immunosuppression. Polyneuropathies that include the facial or other cranial nerves may also be related to concomitant infection with herpes zoster, cytomegalovirus, Treponema pallidum, tuberculosis, or lymphomatous meningitis.

6) Sarcoidosis
Cranial neuropathies, including peripheral facial nerve palsy, are a frequent manifestation of neurosarcoidosis. The facial nerve palsy can be unilateral or bilateral (simultaneous or sequential) and may be recurrent. Patients with neurosarcoidosis may have additional neurologic manifestations, including optic neuropathy, peripheral neuropathy, cognitive impairment, and neuroendocrine dysfunction. Neurosarcoidosis may be diagnosed by brain MRI showing meningeal or parenchymal enhancement, CSF analysis showing an elevated immunoglobulin G (IgG) index and a mononuclear cell pleocytosis, or serologic testing.

7) Sjögren’s disease
Sjögren’s disease can cause multiple central or peripheral neurologic manifestations, including facial nerve palsies or other cranial neuropathies, notably trigeminal sensory loss. However, isolated facial nerve palsy due to Sjögren’s disease is unusual. Neurologic symptoms may precede the diagnosis of Sjögren’s syndrome, but patients typically also have dry eyes, dry mouth, or parotid gland enlargement.

8) Tumor
Neoplastic lesions at the temporal bone, internal acoustic canal, cerebellopontine angle, or parotid gland can compress or infiltrate the facial nerve and cause an ipsilateral weakness of the upper and lower portions of the face. Intracerebral tumors impacting corticobulbar fibers may cause weakness that is typically restricted to the lower portion of the face. Additional findings associated with a facial nerve palsy due to a tumor include:

●Facial twitch or spasm (suggesting ongoing facial nerve irritation) prior to or persisting with weakness
●Simultaneous unilateral hearing loss
●Parotid mass
●Weakness restricted to one or two motor branches of the facial nerve
●Slowly progressive or relapsing course of facial weakness
●Persistent paralysis with no recovery >4 months from onset

9) Leptomeningeal metastases from various solid tumors may cause facial and other cranial neuropathies. Primary tumors that may cause facial nerve palsy include schwannoma of the facial nerve and parotid gland tumor

10) Stroke
Facial weakness due to ischemic stroke or intracerebral hemorrhage that involves motor pathways typically presents as mouth drooping but spares the forehead and eyelid muscles. However, a stroke that affects the ipsilateral facial nerve nucleus or facial nerve tract in the pons can cause facial weakness of the upper (forehead and eyelid muscles) and lower (mouth) muscles that mimics Bell’s palsy.
In addition to forehead-sparing weakness, onset of facial weakness due to stroke is typically sudden and may be associated with additional neurologic signs.

11) Melkersson-Rosenthal syndrome

Question 47

Melkersson-Rosenthal syndrome

Answer 47

• Female predominance
• Recurrent episodes of facial paralysis, episodic facial swelling, and a trifid fissured tongue
• Age at onset varies from early childhood to late adulthood
• Incomplete forms of this syndrome outnumber those with the classic triad
• Granulomatous inflammation is seen in the edematous tissue
• A genetic origin has been suggested, but the cause is unknown and treatment unproven

Question 48

Bell’s palsy management

Answer 48

Question 49

Ramsay Hunt syndrome

Answer 49

• Acute unilateral facial palsy caused by herpes zoster (reflects reactivation of latent VZV in the geniculate ganglion)
• Patients often complain of exquisite pain in the ear prior to the onset of facial weakness 1–3 days later
• On examination, they have eruption of vesicles in the external auditory meatus and over the mastoid process.
• Is more prevalent during pregnancy, and it may involve other cranial nerves, especially the trigeminal nerve.
• Most patients regain full functional facial strength.
• Treatment of Ramsay Hunt syndrome includes corticosteroids
  (1 mg/kg/day, tapering over 10 days) and early administration of acyclovir, 400 mg five times daily for 7–10 days or valacyclovir 2000 to 3000 mg in divided doses
  for 7 to 10 days.

Question 50

Benign hemifacial spasm

Answer 50

• continual facial twitching predominantly around the eye and mouth.
• usually caused by compressive irritation of the facial nerve by an anomalous arterial supply or by a tumor in the cerebellopontine angle
• Treatment typically consists of botulinum toxin injections every 3–6 months.
• More definitive treatment involves tumor removal or microvascular decompression of the facial nerve

Question 51

Ninth nerve injury clinical findings

Answer 51

• loss of the ipsilateral gag reflex
• loss of taste on the posterior one third of the tongue
• diminished sensation in the posterior pharynx

Question 52

Ninth nerve injury differential diagnosis

Answer 52

Disorders that cause focal bulbar motor injury, resulting in dysarthria, hoarseness, and dysphagia.
These disorders include
- infarction
- bulbar amyotrophic lateral sclerosis
- bulbar myasthenia gravis
- rare myopathic disorders (eg, oculopharyngeal dystrophy).

Question 53

Vagus nerve lesion clinical findings

Answer 53

• Hoarseness
• Dysphagia
• Impaired palatal elevation may be seen ipsilateral to the
  lesion, and the uvula deviates away from the side of damage
• Bilateral vagal nerve injury causes significant autonomic
  dysfunction.

Question 54

Spinal accesory nerve injury causes

Answer 54

• iatrogenic damage (eg, lymph node dissection, placement of central venous catheters, other types of neck surgery)
• traumatic injuries such as indirect traction during blunt trauma and dislocations of the sternoclavicular and acromioclavicular joints
• extended use of an arm sling with compression of the spinal accessory nerve
• basilar meningitis

Question 55

Spinal accesory nerve injury differential diagnosis

Answer 55

• central ischemic lesions
• anterior horn cell disease (eg, poliomyelitis or amyotrophic lateral sclerosis)
• injury to peripheral nerves or the proximal brachial plexus, such as the long thoracic nerve (to the serratus anterior) or the branch to the rhomboid muscles, which also produce abnormalities of scapular function and scapular winging
• upper cervical radiculopathy affecting the third and fourth nerve roots can also cause trapezius weakness.
• Myasthenia gravis
• polymyositis
• hereditary myopathies
• mechanical dysfunction secondary to musculoskeletal injury and disease, such as shoulder girdle injury, scapular injury, contracture formation, adhesive capsulitis, and glenohumeral instability, may also suggest trapezius injury.

Question 56

Hypoglossal nerve palsy differential diagnosis

Answer 56

• Ischemia to the medial medulla
• Amyotrophic lateral sclerosis
• Poliomyelitis
• Multiple sclerosis
• syringobulbia
• tumors