Peripheral Neuropathies

PATIENT INFORMATION

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PERIPHERAL NEUROPATHIES= <= o:p>

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Among common problems that result in neuropathies are:=

1. = Mechanical – compression or entrapment of a nerve fibers by surrounding tissues = or tumors

2. = Systemic Diseases (such as diabetes, hypothyroidism, renal failure)

3. = Inherited disorders

4. = Inflammation of the nerve fibers

5. = Ischemic changes (lack of adequate blood supply to the nerve)

6. = Deficiency of nutrients and B-vitamins, alcoholism

7. = Exposure to toxins (solvents, pesticides, heavy metals)

Signs and Symptoms.

Whenever a nerve is damaged, its functions suffer and = corresponding symptoms of deficient function appear.

► If a motor neuron is affect= ed, muscle movement and tone may increase (leading to muscle rigidity, cramps o= r tremors) or decrease (leading to muscle weakness).&= nbsp; Motor manifestations are predominant symptoms in the following disea= ses:

1.      =              Motor neuron disease

2.      =             Multifocal motor neuropathy

3.      =             Guillian-Barré syndrome

4.      =             Acute motor axonal neuropathy

5.      =             Porphiric neuropathy

6.      =             Chronic inflammatory polyradiculoneuropathy

7.      =             Osteosclerotic myeloma

8.      =             Diabetic lumbar radiculoplexopathy

9.      =             Charcot-Marie-Tooth disease (hereditary)

10.      =         Lead intoxication

► If a sensory neuron is affe= cted, abnormal sensations may appear (such prickling, burning, tingling) or normal sensations may disappear (numbness). Neuropathic pain may occur, characterized as deep, burning and shooting. Sensory manifestati= ons are predominant symptoms in the following diseases:

1.      =              Malignant inflammatory sensory polyganglionopathy

2.      =             Sjörgen syndrome

3.      =             Idiopathic sensory polyneuropathy

4.      =             Toxic polyneuropathy (cisplatin and analogues, vitamin B-6 deficiency)=

5.      =             Demyelinating polyradiculoneuropathies

► If an a= utonomic (controlling an internal organ, such as bladder or bowel) neuron is affecte= d, normal function of the corresponding organ or its segment will be impaired,= as is the case in some cases of lightheadedness, fainting spells, reduced or excessive sweating, incontinence, constipation or sexual dysfunction. Even anorexia, early satiety and nausea may be signs of damage of autonomic nerve fibers. Onset of neuropathic symptoms may coincide with weight loss and malaise, suggesting a preceding = or concurrent systemic disorder, such as:

1.      =              Diabetes mellitus

2.      =             Hypothyroidism

3.      =             Renal failure

4.      =             Liver disease

5.      =             Intestinal malabsorption

6.      =             Malignancy

7.      =             Connective tissue diseases

8.      =             HIV

Some rare polyneuropathies may also be accompanied by = loss or darkening of skin’s natural coloration, red/purple coloration of s= kin (purpura<= /span>), or red/purple raised skin spots (angiokeratomas), scale-like appearance of sk= in (ichthyosis), hair loss (alopecia), curling of straight hair.

Neuropathic symptoms may begin acutely (sudden onset) = or develop very slowly; they may remain quite the same (monophasic), or develo= p in severity and complexity (progressive), or be interrupted by periods of improvement and recovery (relapsing). Based upon the number of affected nerves, neuropathies are categoriz= es as mononeuropathies, when a single nerve is implicated, or as polyneuropathies, when s= everal nerves are affected.

ENTRAPMENT NEUROPATHIES

Entrapment neuropathies are local neuropathies caused = by a restriction or mechanical distortion of a nerve. Most entrapment neuropathies result= from trauma (fracture, surgical incision, extensive pressure by an external object like crutches or utility belts) to the area = or from repetitive motions (tennis, golf, cyc= ling) and abnormal postures (leaning on elbows, squa= tting, leg crossing). Carpal tunnel syndrome (median nerve entrapment neuropathy) is by far the most common entrapment neuropathy. It is characterized by pain, tingl= ing numbness and burning of the thumb, index and middle fingers, with pain spreading to the arm and as high as shoulder.

Major nerves in the upper and lower extremity may suff= er from entrapment neuropathies and produce similar symptoms from the wrist to= the shoulder and from upper thigh to the ankle.

H= EREDITARY NEUROPATHIES

These neuropathies are often insidious in onset and sl= ow developing over years and decades. They are often accompanied by a kno= wn metabolic disorder and are quite common disorders in which hereditary natur= e is not be recognized in a large percentage of patients.

Charcot-Marie-= Tooth Disease (Hereditary Motor and Sensory Neuropathy)

This is a case of peroneal muscular dystrophy, which is the most common inherited neuropathy with an estimated prevalence of 1 in 2= 500 in the United States= . This disorder is subdivided into 2 categories, depending on the underlining changes in the nerve structure. Charcot-Marie-Tooth Disease Type 1 is the demyelina= ting (nerve fibers lose protective myelin sheath; see picture above= ) form; Charcot-Marie-T= ooth Disease Type 2 is the neuronal form of the disease, which occurs d= ue to the loss of axons (see picture) – the nerve cells’ main outgoing signal conduit.

Clinical features of the diseases – both diseases present with spinal and foot deformities and difficulty in running and walk= ing; yet type 2 disease presents with fewer upper limb motor abnormalities and m= ore vocal cord and breathing muscle abnormalities. The latter often leads to respirat= ory failure and thus shortens life expectancy for the type 2 patients.

Both of these types occur in adolescents and adults and show mostly an autosomal dominant inherita= nce pattern – only one copy of the gene from either parent is needed for a child to be affected by the disorder. A minority of cases of Charcot-Marie-Tooth Diseases occurs sporadica= lly or in siblings only and has been attributed to either an autosomal recessive inheritance (two copies of abnormal genes from both parents are required to a child to be afflicted wi= th a disorder) or a de novo mutation (a faulty = change in the gene that is completely new, has never existed and could not have be= en transmitted from parent to child)

Rarely, this disease does occur in children, but is referred to as Charcot-Marie-Tooth Disease Type 3, or Dejerine-Sottas disease. This disorder leads to delayed mot= or development and severe disability.

Charcot-Marie-= Tooth Disease Type 4 is a rare autosomal recessive neuropathy characterized by early childhood onse= t, progressive weakness and inability to walk in adolescence. It has been linked to a chromosome= 8 in families of ethnic Tunisian background.

X-linked Domin= ant Charcot-Marie-Tooth Disease is = a form of the disease with differential affliction of males and females. Since the faulty gene in this case= is confined to chromosome X (hence the name, “X-linked”), men, who have only one copy of this chromosome, suffer more severely; whereas women,= who have two X chromosomes (one of them is normal, one has the faulty gene) have mild or no symptoms. No male-to-male transmission occurs.

I= NFLAMMATORY DEMYELINATING POLYRADICULOPATHIES

These diseases are acquired and are mediated through t= he immune system. Therefore, wea= kened immune system presents additional risks of contracting such a radiculopathy= . The acute form is also called Guillain-Barre syndrome; the chronic form does n= ot have a separate name.

Guillain-Barre syndrome is a non-seasonal disease that affects individuals of all ages and is the most c= ommon acute paralytic disease in Western countries. Most patients report having had a preceding event 1-4 weeks prior to developing Guillain-Barre syndrome.=

Most frequent antecedent events are:=

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>1.      = Respiratory illness

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>2.      Gastrointestinal illness

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>3.      Surgery

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>4.      Vaccination

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>a.      = tetanus

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>b.      diphtheria=

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>c.      = rabies

Specific infections linked to inflammatory demyelinati= ng polyradiculopathies are:

1.&n= bsp;      = Campylobacter jejuni<= /i> (frequent cause of enteriti= s)

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>2.      Cytomegalovirus (CMV)

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>3.      Epstein-Barr virus

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>4.      Varicella zoster virus<= /o:p>

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>5.      Hepatitis A

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>6.      Hepatitis B

<= span style=3D'font-size:10.0pt;font-family:Georgia;mso-fareast-font-family:Georg= ia; mso-bidi-font-family:Georgia'>7.      HIV

8.&n= bsp;     = Mycoplasma=

Initial symptoms may vary – sensory only (abnorm= al sensation), motor only (symmetrical lower extremity muscle weakness) or mix= ed. Muscle weakness, having started in= the legs, spreads upward up to the muscles of arm, face and, sometimes, breathi= ng muscles. In some cases, muscle weakness may start with the facial muscles. In its severity, muscle weakness ra= nges from being able to walk unassisted to not being able to move any extremity (quadriplegia).

By 1-4 weeks, progression of symptoms ends. If it does not, it may develop int= o a chronic infl= ammatory demyelinating polyradiculopathy (CIDP). Head muscles are affected in at lea= st a half of patients and facial paresis (inability to voluntarily move a face muscle). Many patients develop moderate to severe pain in the extremities, autonomic symptoms, including cases of alarming heart rate and blood pressure changes.

DIAGNOSIS.<= o:p>

Neurological Examination

A thorough specialized neur= ological examination is necessary to determine where the damage occurred and what ki= nds of motor, sensory or autonomic functions are affected.

Laboratory Testing

Chemical profile, complete blood count, endocrinologic= al tests, urinalysis, toxicology testing may be indicated particularly when symptoms are suspected to be secondary to other diseases, conditions or exposure to neurotoxins.

Biopsy

Biopsy of a nerve may be performed to discover any changes in the structure of the nerve.=

Lumbar Puncture

Sampling of the fluid that surrounds the brain and the spinal cord may be indicated, for instance, to reveal abnormal content of metabolites or presence of infectious agents.

Electrodiagnostic Testing

Electromyography (EMG) and Nerve Conduction Studies (NCV) assess nerve and muscle function and are very helpful for several reasons:

1.      =              Confirm presence of neuropathy

2.      =             To help localize nerve damage and identify its cause

3.      =             To determine any concurrent problems with nerve fibers

Neuroimaging Studies

Imaging studies assess the structure of an organ or area in question.

1.      =              X-Ray

2.      =             Computer Tomography (CT)

3.      =             Magnetic Resonance Imaging (MRI)

4.      =             Contrast studies (special dyes are administered either orally or intravenously)