Sensory Neuropathy

Earn CME/CE in your profession:


Continuing Education Activity

Sensory neuropathy is a common condition that is often a direct complication of another comorbidity. It can be debilitating under certain circumstances, and more widespread awareness across all domains of healthcare is warranted. This activity reviews the evaluation and management of sensory neuropathy and highlights the role of the interprofessional team in managing and improving care for patients with this condition.

Objectives:

  • Summarize the etiologies of sensory neuropathy.
  • Explain the common physical exam findings associated with sensory neuropathy.
  • Outline the management options available for sensory neuropathy.
  • Discuss the importance of interprofessional team strategies for improving care coordination and communication to advance sensory neuropathy and improve outcomes.

Introduction

Sensory neuropathies refer to a host of diseases that result in loss of sensation throughout the body. Collectively, sensory neuropathies can result from a plethora of conditions that this review will discuss. These may further sub-divide into small fiber (pain-dominant) and large fiber (ataxia-predominant) pathologies.

When classifying sensory neuropathy for appropriate treatment and management, nerve size and degree of myelination play a pivotal role. When assessing small fiber neuropathies, the small somatic fibers (Aδ and small unmyelinated C fibers) are of particular interest. These fibers transmit noxious and thermal signals and regulate preganglionic sympathetic and parasympathetic function (Aδ fibers), as well as postganglionic autonomic function (C fibers).[1] Disruption of the normal physiological state of these fibers typically results in burning and shooting pain with paresthesia.

In contrast, large fiber neuropathies result from the attenuation of Aβ fibers, which regulate the proprioceptive signals of vibration and touch. Grossly speaking, patients with sensory ataxia likely possess deformation to the dorsal columns of the spinal cord as well as the dorsal root ganglia.[2] Although ataxia is pathognomonic for large fiber sensory neuropathy, subsequent damage to smaller fibers may occur. As such, some diseases may yield mixed etiology polyneuropathies, which are composed of both small and large fibers (e.g., diabetes mellitus) and present some of the most significant public health burdens in modern-day medicine.[3]

Etiology

Recognizing the varying causative factors directly associated with sensory neuropathy is paramount to providing prompt and effective treatment as a clinician. To gain a more comprehensive stance relative to potential underlying etiologies, one must contemplate the following processes, which include, but are not limited to:

  • Immune-mediated
    • Sarcoidosis, Sjögren syndrome, systemic lupus erythematosus, celiac disease
  • Metabolic
    • Diabetes mellitus, hyperlipidemia
  • Nutritional deficiencies
    • Vitamin B12, copper, vitamin E, folic acid
  • Toxic
    • Chemotherapy, drug-induced, alcohol
  • Hereditary
    • Hemochromatosis, Fabry disease, Ehlers-Danlos syndrome, Friedreich ataxia
  • Infectious
    • Syphilis, leprosy, HIV, hepatitis C, cryoglobulinemia
  • Other
    • Idiopathic, fibromyalgia, vasculitis[4]

When generating differential diagnoses, a direct causative factor may not be readily apparent, and a diagnosis of exclusion (idiopathic sensory neuropathy) must merit consideration, as this constitutes a significant proportion of cases (20 to 30%).[5]

Epidemiology

Studies that have assessed the incidence of sensory neuropathy in the general population report a range of 1 to 3% prevalence, with an increase of up to 7% in the elderly.[5] It has also been shown that developing countries exhibit a lower prevalence, which may, in part, be due to variations in life expectancy. From a global perspective, Western countries are most commonly affected, with a slight predilection towards females.

From a public health standpoint, it is important to note that diabetes mellitus is the leading cause of peripheral neuropathy worldwide.[6] Up to 50% of older patients with diabetes mellitus will acquire some form of distal peripheral neuropathy, which affects their sense of pain and temperature discrimination.[7] A pioneering orthopedic surgeon, Dr. Paul Brand, was renowned for his work on neuropathy which was inspired after working in India, where he noticed that the loss of peripheral sensation ("gift of pain") was the reason his patients with Hansen disease suffered from severe scarring and ulceration. Similarly, in the diabetic population, distal peripheral neuropathy is one of the primary risk factors in the "pathway" to developing diabetic foot complications.[8]

History and Physical

One of the most distinct symptoms of sensory neuropathy is early-onset ataxia. This manifestation is mainly due to the disruption of the afferent neurons, which transmit impulses from the extremities of the body.[9] If these symptoms progress, resultant “writhing” movements will manifest in the hands and feet as the patient closes their eyes.[10] Positive sensory symptoms are also common when small- and medium-sized fibers are affected. Classic clinical findings include complaints of “pins and needles’ and “electricity” in the affected extremities, which follow a stocking-glove pattern. Especially in people with diabetes, a clinician must be vigilant in assessing for negative neuropathic symptoms, which manifest in small-fiber neuropathies. Numbness, as a negative neuropathic symptom, is commonly seen in the feet and is non-length dependent and multifocal.

When performing a subjective patient interview, variability in disease progression will be significant. Subacute sensory neuropathies are commonly seen in immune-mediate and post-infectious cases, whereas idiopathic variants have proven to be more stagnant.[11] In many cases, motor weakness does not accompany sensory neuropathy. However, the motor output may be affected in those with paraneoplastic sensory neuropathies resulting in absent stretch reflexes.

Evaluation

Evaluation criteria regarding sensory neuropathy mainly revolve around neurophysiological examination and dermatopathological studies such as skin biopsy. When diagnosing small fiber neuropathies, electromyography (EMG) results may appear normal, and the presence of sural and plantar responses does not exclude purely small fiber neuropathy. In EMG studies, sensory neuropathies demonstrate a reduced or absent sensory nerve action potential.[12] For patients with diabetic peripheral sensory neuropathy, a Semmes-Weinstein 5.07 monofilament nylon test is often performed at varying locations of the foot to test for a protective threshold (formally defined as 10 grams of force).

Regarding autonomic sensory testing, there are quantitative exams that assess for hot and cold sensation, transient changes in the electrical potential of the skin (e.g., sweat gland activity), and noninvasive electrochemical skin conductance studies for detection of sudomotor dysfunction.[13] For small fiber-dominant neuropathy, some of the most useful studies are thermoregulatory sweat testing and the quantitative sudomotor axon reflex test. Though these studies are not readily available, recent literature shows that their clinical additions yield higher diagnostic success.[14]

The current validated gold standard for the diagnosis of small fiber neuropathy is a skin biopsy.[15] Depending on the research, sensitivities for skin biopsy can be as high as 90%, with specificities as high as 97%.[15][16] The benefits of skin biopsy include ease of use and low morbidity. Common sites of the acquisition include the distal leg, just 10 cm. proximal to the lateral malleolus, and the lateral distal or proximal thigh.[1] In general, nerve biopsy is not necessary for the diagnosis of sensory neuropathy.

Imaging studies also have a role in diagnosing sensory neuropathies and are of greatest utility when assessing for paraneoplastic etiologies. Magnetic resonance imaging and its analogs, inversion recovery MRI pulse sequencing, and T2-weighted spoiled gradient-echo sequencing are of particular merit in visualizing dorsal column pathology.[17]

Treatment / Management

Guidelines pertaining to specific treatment modalities for sensory neuropathies generally do not exist. Much of the data regarding treatments are based on expert opinions, along with well-constructed research. Some treatments include injection of intravenous immunoglobulins, methotrexate, corticosteroids, infliximab, and plasma exchange, among others, depending on the etiology.[18] Recent data suggest that sensory symptomatology generally plateaus after 7 to 10 months.[19] If possible, treatment protocols should initiate within this period.

The efficacy of various oral drugs such as anticonvulsants (pregabalin and oxcarbazepine), serotonin-norepinephrine reuptake inhibitors (duloxetine and venlafaxine), tricyclic antidepressants, opioids (tramadol and tapentadol), and botulinum toxin A (with and without chemodenervation) have demonstrated more effectiveness than a placebo in numerous randomized controlled trials.[20][21] Topical agents such as lidocaine and capsaicin have been recommended with level B evidence per standards from the American Academy of Neurology.

Future clinical avenues for research are promising for the utility of physical exercise in sensory neuropathy secondary to diabetes mellitus. Some of the most current studies show increased nerve fiber density in patients with diabetes mellitus, as well as a measured pain response to exercise in those with established neuropathy.[22][23] Results such as these are encouraging and much warranted as the general etiologies of sensory neuropathy are considered rare as compared to those cases caused by diabetes mellitus, which is far more widespread.

Differential Diagnosis

In a substantial portion of patients, an exact cause of sensory neuropathy is not readily apparent, and the disease is considered idiopathic.[24] Literature suggests that idiopathic sensory neuropathy is a diagnosis of exclusion and that there may be an autoimmune component of the pathophysiology behind the disease.[25] 

Other diseases that may present in a similar clinical fashion include distal acquired demyelinating symmetric neuropathy as well as sensory chronic inflammatory demyelinating polyradiculoneuropathy. These symptoms may also mimic those of other radiculopathies, myelopathies, and various autoimmune diseases.

Prognosis

Outcomes for patients who suffer from different forms of sensory neuropathy will vary. When Wallerian degeneration occurs, a series of events leads to complete structural and chemical disintegration of the nerve and results in a more guarded prognosis. Recovery is contingent on the regeneration of the nerve and depends largely upon how well the transected nerve endings are aligned as well as the severity of any adjacent soft tissue injury and scarring. To achieve a noticeable clinical outcome, the affected muscles and/or organs must become reinnervated after adequate nerve regeneration and remyelination occurs. If the pathology causing any sensory neuropathic symptoms is purely due to segmental demyelination, the prognosis will be much more positive as it entails a shorter recovery with a quicker return to function. Pain and temperature are typically the first sensations to recover.

Regarding those patients with glucose dysregulation, it is vital to monitor their hemoglobin A1c lab value to track the progression of the disease. Current recommendations from the American Diabetes Association underscore maintenance of a value less than 7.0% in conjunction with a healthy lifestyle (diet and exercise) for those with established diabetes.[26]

Complications

If sensory neuropathy is not managed within an acute time frame, the results can be debilitating. Patients will often suffer from varying degrees of burns and other traumatic dermal injuries due to the lack of protective sensation. This sensory loss, in turn, increases the risk of infection secondary to these traumatic events as these injuries are usually not treated quickly and efficiently. In older populations, the risk of accidental falls also increases as balance and strength diminish.

Again, in patients with diabetes mellitus who present with concomitant sensory neuropathy, the complications are significant and life-altering. As a protective threshold is lost, it is not uncommon for a patient to step on a sharp object such as glass or a rusty nail and remain unaware until they notice bleeding from their socks. These injuries are extremely common in the emergency room and constitute a significant challenge for the medical team.

Severe infections leading to sepsis and gangrene of the lower extremities due to chronic neuropathic ulcerations or retention of a foreign body is one of the leading causes of amputation in people with diabetes. The overall risk of developing diabetic foot ulceration is around 2% per year; that statistic increases to about 7% in those with sensory neuropathy, a staggering causal finding.[8] To mitigate these risks, proper patient education in conjunction with a communicative multidisciplinary healthcare team is essential.

Deterrence and Patient Education

To effectively deter the course of this disease, clinicians must adequately educate patients on the potential signs and symptoms previously discussed. It is also equally important to make necessary alterations in daily life if a patient does begin to notice symptoms. Patients with established sensory neuropathy should limit their exposure to temperature extremes and monitor sudden, obvious changes in gait patterns to diminish the effects of repetitive micro-motion to their feet; modifications in shoe gear may also be necessary.

For diabetic patients, an established daily foot screening protocol should be performed daily for early detection of possible lesions. These patients should also schedule frequent visits with their podiatric physician at least every 2 to 3 months for formal evaluation and care as part of a holistic approach to the management of their sensory neuropathy. A primary care physician or an endocrinologist also plays a vital role in the overall management of diabetes and the limitation of sensory neuropathy symptomatology.

Enhancing Healthcare Team Outcomes

The availability of healthcare as a whole is not genuinely ubiquitous in all parts of the world, and strides are necessary to provide evidence-based treatment via an interprofessional team approach to those in need. As patient education is essential in the prevention of sensory neuropathy-related morbidities, so are the neurologists, vascular surgeons, physical and occupational therapists, infectious disease specialists, endocrinologists, and podiatric physicians, who each provide essential tools from their armamentaria to combat this disease and its symptoms.


Article Details

Article Author

Elias Gomatos

Article Editor:

Anis Rehman

Updated:

7/11/2021 10:33:06 PM

PubMed Link:

Sensory Neuropathy

References

[1]

Hoeijmakers JG,Faber CG,Lauria G,Merkies IS,Waxman SG, Small-fibre neuropathies--advances in diagnosis, pathophysiology and management. Nature reviews. Neurology. 2012 May 29;     [PubMed PMID: 22641108]

[2]

Siao P,Kaku M, A Clinician's Approach to Peripheral Neuropathy. Seminars in neurology. 2019 Oct;     [PubMed PMID: 31639835]

[3]

Boulton AJM,Armstrong DG,Kirsner RS,Attinger CE,Lavery LA,Lipsky BA,Mills JL Sr.,Steinberg JS, 2018 Oct;     [PubMed PMID: 30958663]

[4]

Ginsberg L, Vasculitis and the peripheral nervous system. Rheumatology (Oxford, England). 2020 May 1;     [PubMed PMID: 32348511]

[5]

Hanewinckel R,van Oijen M,Ikram MA,van Doorn PA, The epidemiology and risk factors of chronic polyneuropathy. European journal of epidemiology. 2016 Jan;     [PubMed PMID: 26700499]

[6]

Gordon Smith A,Robinson Singleton J, Idiopathic neuropathy, prediabetes and the metabolic syndrome. Journal of the neurological sciences. 2006 Mar 15;     [PubMed PMID: 16448668]

[7]

Boulton AJM,Armstrong DG,Hardman MJ,Malone M,Embil JM,Attinger CE,Lipsky BA,Aragón-Sánchez J,Li HK,Schultz G,Kirsner RS, 2020 Jan;     [PubMed PMID: 32105420]

[8]

Armstrong DG,Boulton AJM,Bus SA, Diabetic Foot Ulcers and Their Recurrence. The New England journal of medicine. 2017 Jun 15;     [PubMed PMID: 28614678]

[9]

Sghirlanzoni A,Pareyson D,Lauria G, Sensory neuron diseases. The Lancet. Neurology. 2005 Jun;     [PubMed PMID: 15907739]

[10]

Sheikh SI,Amato AA, The dorsal root ganglion under attack: the acquired sensory ganglionopathies. Practical neurology. 2010 Dec;     [PubMed PMID: 21097829]

[11]

Dalakas MC, Chronic idiopathic ataxic neuropathy. Annals of neurology. 1986 Jun;     [PubMed PMID: 3014995]

[12]

Camdessanché JP,Antoine JC,Honnorat J,Vial C,Petiot P,Convers P,Michel D, Paraneoplastic peripheral neuropathy associated with anti-Hu antibodies. A clinical and electrophysiological study of 20 patients. Brain : a journal of neurology. 2002 Jan;     [PubMed PMID: 11834602]

[13]

Lefaucheur JP,Wahab A,Planté-Bordeneuve V,Sène D,Ménard-Lefaucheur I,Rouie D,Tebbal D,Salhi H,Créange A,Zouari H,Ng Wing Tin S, Diagnosis of small fiber neuropathy: A comparative study of five neurophysiological tests. Neurophysiologie clinique = Clinical neurophysiology. 2015 Dec;     [PubMed PMID: 26596193]

[14]

Thaisetthawatkul P,Fernandes Filho JA,Herrmann DN, Contribution of QSART to the diagnosis of small fiber neuropathy. Muscle     [PubMed PMID: 23649502]

[15]

England JD,Gronseth GS,Franklin G,Carter GT,Kinsella LJ,Cohen JA,Asbury AK,Szigeti K,Lupski JR,Latov N,Lewis RA,Low PA,Fisher MA,Herrmann DN,Howard JF,Lauria G,Miller RG,Polydefkis M,Sumner AJ, Practice parameter: the evaluation of distal symmetric polyneuropathy: the role of laboratory and genetic testing (an evidence-based review). Report of the American Academy of Neurology, the American Association of Neuromuscular and Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation. PM     [PubMed PMID: 19627867]

[16]

Hays AP, Utility of skin biopsy to evaluate peripheral neuropathy. Current neurology and neuroscience reports. 2010 Mar;     [PubMed PMID: 20425234]

[17]

Bao YF,Tang WJ,Zhu DQ,Li YX,Zee CS,Chen XJ,Geng DY, Sensory neuronopathy involves the spinal cord and brachial plexus: a quantitative study employing multiple-echo data image combination (MEDIC) and turbo inversion recovery magnitude (TIRM). Neuroradiology. 2013 Jan;     [PubMed PMID: 22922867]

[18]

Tavee JO,Karwa K,Ahmed Z,Thompson N,Parambil J,Culver DA, Sarcoidosis-associated small fiber neuropathy in a large cohort: Clinical aspects and response to IVIG and anti-TNF alpha treatment. Respiratory medicine. 2017 May;     [PubMed PMID: 28318820]

[19]

Antoine JC,Robert-Varvat F,Maisonobe T,Créange A,Franques J,Mathis S,Delmont E,Kuntzer T,Lefaucheur JP,Pouget J,Viala K,Desnuelle C,Echaniz-Laguna A,Rotolo F,Camdessanché JP, Identifying a therapeutic window in acute and subacute inflammatory sensory neuronopathies. Journal of the neurological sciences. 2016 Feb 15;     [PubMed PMID: 26810539]

[20]

Lakhan SE,Velasco DN,Tepper D, Botulinum Toxin-A for Painful Diabetic Neuropathy: A Meta-Analysis. Pain medicine (Malden, Mass.). 2015 Sep;     [PubMed PMID: 25800040]

[21]

Waldfogel JM,Nesbit SA,Dy SM,Sharma R,Zhang A,Wilson LM,Bennett WL,Yeh HC,Chelladurai Y,Feldman D,Robinson KA, Pharmacotherapy for diabetic peripheral neuropathy pain and quality of life: A systematic review. Neurology. 2017 May 16;     [PubMed PMID: 28341643]

[22]

Singleton JR,Marcus RL,Jackson JE,K Lessard M,Graham TE,Smith AG, Exercise increases cutaneous nerve density in diabetic patients without neuropathy. Annals of clinical and translational neurology. 2014 Oct;     [PubMed PMID: 25493275]

[23]

Kluding PM,Pasnoor M,Singh R,Jernigan S,Farmer K,Rucker J,Sharma NK,Wright DE, The effect of exercise on neuropathic symptoms, nerve function, and cutaneous innervation in people with diabetic peripheral neuropathy. Journal of diabetes and its complications. 2012 Sep-Oct;     [PubMed PMID: 22717465]

[24]

Gwathmey KG,Pearson KT, Diagnosis and management of sensory polyneuropathy. BMJ (Clinical research ed.). 2019 May 8;     [PubMed PMID: 31068323]

[25]

Dalakas MC, Pathogenesis of immune-mediated neuropathies. Biochimica et biophysica acta. 2015 Apr;     [PubMed PMID: 24949885]

[26]

Sherwani SI,Khan HA,Ekhzaimy A,Masood A,Sakharkar MK, Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients. Biomarker insights. 2016;     [PubMed PMID: 27398023]