Neuropathy


Article Author:
Claudia Hammi


Article Editor:
Brent Yeung


Editors In Chief:
Kranthi Sitammagari
Mayank Singhal


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Kyle Blair
Trevor Nezwek
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Daniyal Ameen
Altif Muneeb
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes
Komal Shaheen
Sandeep Sekhon


Updated:
6/4/2019 4:03:17 PM

Introduction

Peripheral neuropathies encompass disorders of peripheral nerve cells and fibers which manifest secondary to a wide range of pathologies. These nerves include cranial nerves, spinal nerve roots & ganglia, nerve trunks & division, along with nerves of the autonomic nervous system.[1] There are several methods used to classify peripheral neuropathies including categorizing them as mono-neuropathies, multifocal neuropathies, and poly-neuropathies. Further subclassifications can be made separating peripheral neuropathies as axonal, demyelinating, or mixed, which is essential for treatment and management purposes.[2] The most frequently encountered symptoms of peripheral neuropathy include numbness and paresthesias; pain, weakness, and loss of deep tendon reflexes may accompany these symptoms. Peripheral neuropathies usually develop over months to years, while some may develop more rapidly and be progressive in nature. Peripheral neuropathies have a broad range of severity and clinical manifestations as they can affect motor, sensory, and autonomic fibers.

Etiology

Peripheral neuropathies stem from a variety of origins including metabolic, systemic, and toxic causes. Underlying etiologies to consider include: 

  • Diabetes mellitus
  • Chronic alcoholism
  • Nutritional deficiencies (e.g., B1,B6, B12, vitamin E)
  • Inflammatory conditions (e.g., vasculitis)
  • Hypothyroidism
  • Autoimmune disease (e.g., Sjogren syndrome, lupus, rheumatoid arthritis)
  • Infections (e.g.,  Lyme disease, Epstein-Barr virus, hepatitis C, shingles, leprosy, HIV)
  • Guillain-Barre syndrome
  • Toxins (heavy metals, chemicals)
  • Chemotherapy agents
  • Medications (antibiotics, cardiovascular medications)
  • Tumors (secondary to compression or associated paraneoplastic syndromes)
  • Inherited conditions (e.g., Charcot-Marie-Tooth disease, familial amyloidosis)
  • Trauma/injury
  • Multiple myeloma and its treatments
  • Monoclonal gammopathy of undetermined significance (MGUS)

In some cases, a direct cause may not be apparent.

Epidemiology

About 2.4% of the population is affected by peripheral nerve disorders; the prevalence increases to 8.0% in older populations.[3] Diabetic neuropathy occurs in approximately half of individuals with chronic type 1 and type 2 diabetes. Globally, leprosy remains a common cause of peripheral neuropathy, with the highest prevalence in South East Asia.

The most common genetic sensorimotor polyneuropathy is Charcot-Marie-Tooth disease, specifically, type 1a. The most common mononeuropathy is carpal tunnel syndrome. 

Pathophysiology

The exact pathophysiology of peripheral neuropathy is contingent on the underlying disease. Although a wide assortment of distinct diseases can ultimately lead to peripheral neuropathies, the mechanisms in which peripheral nerves suffer injury exhibit similar patterns. These reactions include segmental demyelination, along with Wallerian and axonal degeneration. 

  • Segmental Demyelination: This process refers to the process of degeneration of the myelin sheath, with sparing of the nerve axon. This type of reaction can present in mononeuropathies, sensorimotor, or principally motor neuropathies. These are often inflammatory and sometimes immune-mediated. About 20% of symmetrical peripheral neuropathies result from damage to the myelin. Examples include Charcot-Marie-Tooth and neuropathy associated with monoclonal gammopathy of undetermined significance.
  • Wallerian Degeneration: This occurs after a nerve axon degenerates due to a lesion or physical compression, the portion distal to the axon passively wastes away, likely due to lack of nutrients from the cell body. This reaction results in a focal mononeuropathy that is secondary to trauma or infarction of the nerve.[4] Wallerian Degeneration is immunohistochemically distinct by the localization of neuropeptide Y-Y1 receptor markers.[5] 
  • Axonal Degeneration, also known as the dying-back phenomenon: This type of degeneration usually manifests as symmetrical polyneuropathy (around 80%) and tends to cause weakness, most notably weakness in dorsiflexion of the ankles and foot, with accompanied trophic changes to muscle. The axon degenerates in a pattern that starts distal and progresses proximally; this is thought to be because the most distal portion of the axon is particularly vulnerable due to its distance from the cell body which provides metabolic support.[6] A proposed mechanism is that insult to the nerve causes impaired delivery of local axonal survival factors, resulting in an increased level of calcium intra-axonal leading to a calcium-dependent cytoskeletal breakdown.[7] Examples of diseases causing axonal degeneration include diabetes, HIV, HCV, and Guillain-Barre syndrome.[8]

History and Physical

The clinical presentation of peripheral neuropathy widely varies depending on the underlying disease process. Patients may complain of symptoms initially starting in their digits, progressing to their proximal limbs. Symptoms range and include changes in sensation, weakness, atrophy, pain, numbness, and even autonomic disturbances. Clinically, these symptoms may resemble that of myelopathies, radiculopathies, autoimmune disease, and diseases of muscles. Advanced disease may progress to reduced or absent deep tendon reflexes, stocking-glove pattern sensory loss, muscle wasting, and weakness.[3] Obtaining a thorough history is vital in helping to uncover the primary cause of the neuropathy. Aside from a meticulous review of past medical history, providers should inquire about toxic exposures, present and past medications, trauma, dietary and nutritional deficiencies, and alcohol use.

Evaluation

Evaluating patients with neuropathy involves a detailed history and physical including a review of current and past medications. Although there are no standard laboratory or imaging studies to test for peripheral neuropathies, the following studies may aid in the diagnosis and help narrow down the underlying cause of the neuropathy (e.g., inflammatory, infectious, metabolic):  

  • Complete Blood Count (Macrocytic anemia may clue the clinician to vitamin B12 or folate deficiency, or even alcohol abuse)
  • Metabolic Panels such as BMP or CMP (Look for electrolyte imbalances that can contribute to neuropathy along with renal failure as uremia can also lead to neuropathy).[9]
  • HbA1c Testing (Diabetes is a common cause of neuropathy)
  • Testing for vitamin and mineral deficiencies such as copper, thiamine, pyridoxine, folate, B12, and vitamin E which play fundamental roles in nervous system development and maintenance. 
  • Heavy metal toxicities such as mercury, lead, arsenic are known to cause peripheral nerve toxicities along with CNS disturbances.[9]
  • Infectious workup for Lyme disease, Epstein-Barr virus, hepatitis C, HIV, and syphilis as a long-standing disease may manifest with peripheral neuropathies and paresthesias.[10][11][12]
  • Thyroid function testing.[13]
  • Anti-body testing for specific autoimmune diseases known to cause peripheral neuropathies such as Sjogren syndrome, lupus, rheumatoid arthritis.[14]
  • Nerve conduction study and electromyography (EMG)
  • MRI or CT scans in cases where compression of the nerve is of concern
  • Nerve biopsy
  • Genetic testing (for inherited neuropathies)
  • Urine Test (looking for Bence-Jones proteins as multiple myeloma and its treatments can cause peripheral neuropathy)

Treatment / Management

Treatment of peripheral neuropathies should focus on the treatment of the underlying disease process. For example, glucose control in diabetic neuropathy, alcohol cessation in alcoholic neuropathy. Nutritional deficiencies can have therapy with supplementation of the depleted vitamins or minerals. Unfortunately, not all peripheral neuropathies are reversible. Physical therapy and occupational therapy can be initiated to aid in the improvement of a patient's overall strength and function. Chronic inflammatory demyelinating neuropathy is treated using corticosteroids initially, but can also be treated using intravenous immunoglobulin, plasma exchange, and some immunosuppressant drugs.[15]

A referral to a pain specialist can be beneficial for those patients who are suffering from neuropathic pain. Neuropathic pain, particularly in those suffering from small-fiber neuropathies, do not typically respond to simple analgesics. Instead, effective treatment for pain associated with peripheral neuropathies can be with membrane stabilizers, certain anti-epileptics, and tricyclic antidepressants.[16] Transcutaneous electrical nerve stimulation (TENS) is also an option as a noninvasive intervention for pain relief.

Differential Diagnosis

Differentials to consider greatly vary depending on clinical presentation. Symptoms of peripheral neuropathies may resemble that of myelopathies, radiculopathies, autoimmune disease, and diseases of muscles.

Prognosis

In those diseases where peripheral nerves suffer damage through Wallerian or axonal degeneration, the prognosis is poorer, as the recovery of the nerve is more challenging. For clinical improvement to take place, the axon must regenerate itself, and reinnervate the affected muscle or organ. The prognosis of diseases which occur secondary to segmental demyelination is more favorable because remyelination is achieved more quickly, allowing the return of function of the axon.

Complications

Complications of peripheral neuropathies include pain, altered sensation, muscle atrophy, and weakness. Diabetic peripheral neuropathy is infamous for complications including foot ulcers which can lead to gangrenous digits and limbs, sometimes progressing to amputation.

Consultations

Consultations and referrals to consider for patients suffering from peripheral neuropathy include:

  • Neurologist
  • Chronic pain physician
  • Physical therapy
  • Occupational therapy
  • Endocrinologist 
  • Rheumatologist
  • Psychiatry & addiction medicine (for those with alcohol-induced peripheral neuropathy)
  • Infectious disease specialist
  • Surgeon (for neuropathy secondary to compression)
  • Hematology/oncology (for those with neuropathy related to cancer)

Deterrence and Patient Education

Patients require education on the signs and symptoms of peripheral neuropathy. Patients should be made aware that they have an increased risk of injury due to loss of sensation, they should be conscious of any new cuts or damage to their skin as wound healing can be delayed, and risk for infection increases. Recommend always wearing socks with closed-toed shoes to decrease the risk of infection. Patients should take caution when exposing themselves to hot or cold environments to avoid burns and frostbite. Patients with diabetes should receive counseling on managing their diabetes appropriately. Patients with alcohol-induced neuropathy should get information on cessation.

Pearls and Other Issues

  • Charcot-Marie-Tooth is the most commonly inherited cause of peripheral neuropathy[17]
  • Demyelinating neuropathies are commonly inflammatory in nature and often treatable[3]

  • Neurophysiological tests can differentiate axonal from demyelinating neuropathies

  • Overall, the most common polyneuropathy is diabetic sensorimotor polyneuropathy[3]
  • Peripheral neuropathy can be into divided into mono-neuropathies, multifocal neuropathies, and poly-neuropathies, with further subclassifications into axonal, demyelinating, or mixed type.

  • Neuropathic pain can be effectively treated with membrane stabilizers, certain anti-epileptics, and tricyclic antidepressants

Enhancing Healthcare Team Outcomes

A wide range of disease processes can lead to peripheral neuropathies, which routinely requires a multidisciplinary team approach to diagnosis and treatment. This team should include physicians, specialists, specialty-trained nurses, and when necessary, pharmacists, all working collaboratively to achieve optimal patient care and outcomes. [Level V] Neuropathies can be both painful and debilitating for patients. Thus it is vital to acquire a prompt diagnosis of the underlying condition followed by the initiation of appropriate treatment(s) to reverse, slow, or stop the progression of the disease. Identifying patients most at risk for neuropathies and implementing a preventative approach to their care can undoubtedly improve outcomes for patients, as seen in the case of diabetic neuropathy. As primary care providers and nurse practitioner are often the first to work-up these patients, it is imperative that they are familiar with the full range of etiologies that play a role in the development of peripheral neuropathies, including testing and referrals to the appropriate specialists.  


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Neuropathy - Questions

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A 45-year-old male presents to his primary care provider complaining of numbness and pain in his hands and feet bilaterally, worsening over the past year. He describes the pain as burning and constant. His past medical history includes HIV diagnosed 7 years ago, he stopped taking his medications 2 years ago. Neuropathic pain occurs in what percentage of patients with HIV?



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A 70-year-old male with a past medical history of chronic smoking, well-controlled diabetes, and coronary artery disease presents with three months of rib pain that has worsened over the last two weeks secondary to cough. He also states around this time he began having a burning sensation in his hands, sometimes associated with numbness and tingling. Chest x-ray reveals punched-out lytic bone lesions on multiple ribs. His labs are significant for the following: calcium 12.3 mg/dL, BUN 15 mmol/L, creatinine 1.7 mg/dL, and hemoglobin 9.8 g/dL. Which of the following tests would help to identify the cause of his peripheral neuropathy?



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A 65-year-old male presents to his primary care provider complaining of numbness and tingling in his feet bilaterally, worsening over the past 6 months. He also complains of weakness in his bilateral lower extremities. His past medical history includes hypertension controlled with lisinopril and type 2 diabetes on metformin. His latest hemoglobin A1c is 10.5%. On physical exam, he has +5/5 muscle strength in his bilateral lower extremities but diminished sensation to light touch. Which of the following helps to differentiate myopathy from neuropathy?



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Needle electromyographic studies demonstrate a distal latency of 7.5 ms in the abductor hallucis and a distal latency of 6.0 ms in the abductor digiti quinti. Which branch of the posterior tibial nerve is most likely to be the cause of this neuropathy?



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Neuropathy - References

References

Hanewinckel R,Ikram MA,Van Doorn PA, Peripheral neuropathies. Handbook of clinical neurology. 2016;     [PubMed]
Remiche G,Kadhim H,Maris C,Mavroudakis N, [Peripheral neuropathies, from diagnosis to treatment, review of the literature and lessons from the local experience]. Revue medicale de Bruxelles. 2013 Sep;     [PubMed]
Staff NP,Windebank AJ, Peripheral neuropathy due to vitamin deficiency, toxins, and medications. Continuum (Minneapolis, Minn.). 2014 Oct;     [PubMed]
Halperin JJ,Little BW,Coyle PK,Dattwyler RJ, Lyme disease: cause of a treatable peripheral neuropathy. Neurology. 1987 Nov;     [PubMed]
Köşkderelioğlu A,Ortan P,Ari A,Gedizlioğlu M, Screening for Electrophysiological Abnormalities in Chronic Hepatitis C Infection: Peripheral Neuropathy and Optic Neuropathy. Noro psikiyatri arsivi. 2016 Mar;     [PubMed]
Saylor D,Nakigozi G,Nakasujja N,Robertson K,Gray RH,Wawer MJ,Sacktor N, Peripheral neuropathy in HIV-infected and uninfected patients in Rakai, Uganda. Neurology. 2017 Aug 1;     [PubMed]
Berkowitz AL,Samuels MA, The neurology of Sjogren's syndrome and the rheumatology of peripheral neuropathy and myelitis. Practical neurology. 2014 Feb;     [PubMed]
Karne SS,Bhalerao NS, Carpal Tunnel Syndrome in Hypothyroidism. Journal of clinical and diagnostic research : JCDR. 2016 Feb;     [PubMed]
Hughes RA, Peripheral neuropathy. BMJ (Clinical research ed.). 2002 Feb 23;     [PubMed]
Martyn CN,Hughes RA, Epidemiology of peripheral neuropathy. Journal of neurology, neurosurgery, and psychiatry. 1997 Apr;     [PubMed]
Singh S,Dallenga T,Winkler A,Roemer S,Maruschak B,Siebert H,Brück W,Stadelmann C, Relationship of acute axonal damage, Wallerian degeneration, and clinical disability in multiple sclerosis. Journal of neuroinflammation. 2017 Mar 17;     [PubMed]
Freeman MR, Signaling mechanisms regulating Wallerian degeneration. Current opinion in neurobiology. 2014 Aug;     [PubMed]
Sumner AJ,Asbury AK, Physiological studies of the dying-back phenomenon. Muscle stretch afferents in acrylamide neuropathy. Brain : a journal of neurology. 1975 Mar;     [PubMed]
Wang JT,Medress ZA,Barres BA, Axon degeneration: molecular mechanisms of a self-destruction pathway. The Journal of cell biology. 2012 Jan 9;     [PubMed]
Sindrup SH,Jensen TS, Pharmacologic treatment of pain in polyneuropathy. Neurology. 2000 Oct 10;     [PubMed]
Saperstein DS,Katz JS,Amato AA,Barohn RJ, Clinical spectrum of chronic acquired demyelinating polyneuropathies. Muscle     [PubMed]
Cashman CR,H�ke A, Mechanisms of distal axonal degeneration in peripheral neuropathies. Neuroscience letters. 2015 Jun 2;     [PubMed]

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