Periphral neuropathy

Peripheral neuropathy

Peripheral Neuropathy: are composed of sensory, motor, and autonomic elements. Diseases can affect the cell body of a neuron or its peripheral processes, namely the axons or the encasing myelin sheaths. Most peripheral nerves are mixed and contain sensory and motor as well as autonomic fibers. Thus, peripheral neuropathies can impair sensory, motor, or autonomic function, either singly or in combination.

MONONEURITIS SIMPLEX

This term signifies involvement of a single peripheral nerve.

MONONEURITIS MULTIPLEX

Several individual nerves are affected, usually at random and noncontiguous.

POLYNEUROPATHY

The term “polyneuropathy” denotes a disorder in which the function of numerous peripheral nerves is affected at the same time. This leads to a predominantly distal and symmetric deficit, with loss of tendon reflexes except when small fibers are selectively involved.
Approach to Neuropathic Disorders
Is it Motor, sensory, autonomic, or combinations?
Is it focal, symmetrical or asymmetrical?
Is it Acute (days to 4 weeks), Subacute (4 to 8 weeks) or Chronic (>8 weeks)?
Is there evidence for a hereditary neuropathy(family history)
Are there any associated medical conditions (DM, cancer, autoimmune, connective tissue)?
Drug history.


Causes of peripheral neuropathy
Idiopathic inflammatory neuropathies
Acute idiopathic polyneuropathy (Guillain-Barré syndrome)
Chronic inflammatory demyelinating polyneuropathy.(CIDP)

Metabolic and nutritional neuropathies

Diabetes
Hypothyroidism
Vitamin B12 deficiency

Infective and granulomatous neuropathies

AIDS, leprosy, diphtheria, sarcoidosis and sepsis.
Vasculitis neuropathies
Polyarteritis nodosa
Rheumatoid arthritis
SLE

Neoplastic and paraproteinemic neuropathies

Compression and infiltration by tumor
Paraneoplastic syndromes
Paraproteinemias


Drug ,alcohol and toxin induced neuropathies
Examples of drugs
Pyridoxine
Metronidazole
Dapsone
Isoniazid
Example of toxin:
Organophosphates
7- Heavy metal
Lead, Thallium, arsenic
8- Hereditary neuropathies
Friedreich ataxia, CMT (Charcot-Marie-Tooth), porphyria
9-compressive neuropathy:
E.g.: carpel tunnel syndrome

IDIOPATHIC INFLAMMATORY NEUROPATHIES

Acute Idiopathic Polyneuropathy (Guillain-Barré Syndrome)
GBS is an acute or subacute polyneuropathy that can follow minor infective illnesses, ,vaccination ,surgical procedures, or may occur without obvious precipitants .Clinical and epidemiologic evidence suggests an association with preceding infection such as Campylobacter jejuni, Cytomegalovirus , Mycoplasma pneumonia, Epstein–Barr virus etc.. Its precise cause is unclear, but it appears to have an immunologic basis. Both demyelinating and axonal forms have been recognized, with distinctive clinical and electrophysiological features. The demyelinated form is more common.

CLINICAL FEATURES

Diagnostic criteria for Guillain-Barré syndrome
Required for diagnosis
Progressive weakness of more than one limb
Distal areflexia with proximal areflexia or hyporeflexia
Supportive of diagnosis
Progression for up to 4 weeks
Recovery beginning within 4 weeks after progression stops
Relatively symmetric deficits
Mild sensory involvement
Cranial nerve (especially VII) involvement
Autonomic dysfunction
No fever at onset
Increased CSF protein after 1 weeks
CSF white blood cell count ≤10/ìL
Nerve conduction study show slowing or block by several weeks

Against diagnosis

Markedly asymmetric weakness
Bowel or bladder dysfunction (at onset or persistent)
CSF white blood cell count >50 or PMN count >O/ìL
Well-demarcated sensory level
Excluding diagnosis
Isolated sensory involvement
Investigative studies
The cerebrospinal fluid (CSF) often shows a characteristic abnormality, with increased protein concentration but a normal cell count (cytoalbumino dissociation); abnormalities may not be found in the first week.
Electrophysiological studies may reveal marked slowing of motor and sensory conduction velocity.
TREATMENT
Plasmapheresis appears to reduce the time required for recovery and may decrease the likelihood of residual neurologic deficits and need for ventilation a course of plasmapheresis usually consists of 40–50 mL/kg plasma exchange (PE) four to five times. It is best instituted early, and it is indicated especially in patients with a severe or rapidly progressive deficit or respiratory compromise.
Intravenous immunoglobulin (400 mg/kg/d for 5 days) appears to be equally effective and should be used in preference to plasmapheresis in adults with cardiovascular instability and in children; the two therapies are not additive.no role for steroid.
In the worsening phase of GBS, most patients require monitoring in a critical care setting, with particular attention to
Vital capacity
Heart rhythm
Blood pressure
Nutrition
Deep vein thrombosis prophylaxis like heparin and compressive stokes
Cardiovascular status monitoring, and chest physiotherapy.
As noted, 30% of patients with GBS require ventilator assistance.


Prognosis and Recovery
Approximately 70-75% of patients recover completely, 25% are left with mild neurologic deficits, and 5% die from respiratory and autonomic dysfunction.

Chronic Inflammatory Demyelinating Polyneuropathy

CIDP is distinguished from GBS by its chronic course. Onset is usually gradual over a few months or longer, but in a few cases the initial attack is indistinguishable from that of GBS. An acute-onset form of CIDP should be considered when GBS deteriorates >9 weeks after onset or relapses at least three times. Symptoms are both motor and sensory in most cases. In other respects, this neuropathy shares many features with the common demyelinating form of GBS.
Thoracoabdominal radiculopathy (Chest, abdomen)
Mononeuritis simplex
Peripheral (Ulnar, median, radial, lateral femoral cutaneous, sciatic, peroneal, other nerves).
Cranial (Oculomotor (III) > abducent (VI) > trochlear (IV) )
Autonomic (e.g. impotence).

END

Appendix (added by the students not included in the lecture):

Case (1) A 32-year-old Caucasian male is admitted to the hospital due to a 1-week history of progressive paralysis of his upper and lower extremities. He had a flu-like illness 3 weeks ago. followed by paresthesias in his fingertips and toes. The weakness initially started in his lower extremities. He denies any changes in bowel and bladder functions. His blood pressure (supine) is 130/70mm Hg. heart rate is 82/min. respirations are 18/min. and temperature is 36 .9C(98 .5F). Physical examination reveals bilateral facial paralysis. orthostatic hypotension. areflexia in all four extremities. and distal paresthesias. His CSF analysis shows:
Total WBC 3/mm3
Protein 120 mg/dl
Glucose 70 mg/dl
Gram stain No organisms
What is the most appropriate next step in the management of this patient?
Intravenous methyl prednisolone
Intravenous immunoglobulin therapy
Intravenous acyclovir therapy
Botulinum antitoxin
Intravenous ceftriaxone and ampicillin
Explanation:
The most likely diagnosis is Guillain-Barre syndrome (GBS). The classic presentation includes ascending paralysis. areflexia and sensory changes 3-4 weeks after an upper respiratory tract infection or gastroenteritis. Albumino-cytologic dissociation (elevated protein despite normal cell count) is a fairly specific feature. Cranial nerve paralysis (most likely facial nerve palsy) often develops. Up to 50% of patients present with autonomic dysfunction of varying severity; these patients should be treated with immunoglobulin and plasmapheresis.
So the answer is B
Case (2) A 30-year-old Caucasian male comes to the office due to symmetric weakness of his lower extremities. He also has paresthesias in his toes and fingers, and lower back pain. The neurological examination shows symmetric weakness, diminished reflexes, and intact sensation in his lower extremities. Orthostatic hypotension is also noted. Electrophysiological studies show slowed nerve conduction velocities. Lumbar puncture reveals normal opening pressure. CSF examination shows few cells, and a protein concentration of 90 mg/dL. Which of the following organisms is involved in the pathogenesis of this disorder?
Campylobacter jejuni
Chlamydia
Shigella
Salmonella
E.coli (0157 H7)
Explanation:
More than two-third patients of Guillain-Barre Syndrome (GBS) have an antecedent respiratory or gastrointestinal infection. Campylobacter jejuni is the most frequent precipitant of GBS. Other precipitants include human Herpes viruses, Mycoplasma and Hemophilus influenzae. GBS occurs more frequently in patients with lymphoma, sarcoidosis and systemic lupus erythematosus. Recent HIV infection and recent immunization have also been associated with GBS.
So the answer is A