In certain medical conditions, a patient can experience abnormal sensations in their arms and legs.

In the arms, this is most commonly seen with carpal tunnel syndrome. This is where an individual will feel a recurring sensation of pins and needles in specific fingers, because the median nerve is trapped under pressure at the wrist. In the leg, we might see this with sciatica, where there is pressure on the sciatic nerve in the spine, causing pins and needles or loss of sensation in the area that corresponds to the nerve under pressure. 

In other situations doctors will find that the patient complains of a sensation of pins and needles or numbness which does not fit a particular pattern. The Canadian researchers in this article have highlighted the problem of arriving at a diagnosis of abnormal sensation and called for studies into the matter.

Clinically, this is an important issue. A related study has found that 25% of people with low back problems have some symptoms of abnormal leg sensation. This may be pain in a particular area of the leg, or sensory disturbance such as pins and needles or numbness without specific sciatica complaints. Patients with fibromyalgia also often complain of abnormal sensation in their arms.

Often doctors will believe abnormal sensations are significant and pursue investigations, perhaps even resulting in a specialist referral. It is important for medical practitioners to be better able to understand this area in order to help them differentiate between the specific medical condition, a nonspecific symptom simply occurring as part of a clinical condition, and when certain symptoms are not a cause for concern.

The researchers point out that the patients may report reduced sensation when they are examined. The examination findings may not correlate with the specific nerve. For example, sometimes patients will say they have reduced sensation to a pinprick throughout their entire leg. 

Some people believe that when there are abnormal sensations that do not correlate with a particular medical condition, it suggests that the person is going to have a poor prognosis and response to treatment. But this is not known for sure, and doctors may be assuming nonspecific symptoms are a negative factor. 

This article highlights the issue and acknowledges that doctors should accept abnormal sensation as a common symptom, without necessarily assuming that it is a worrying condition or that it indicates a poor prognosis.

Authors

Mailis-Gagnon A. Nicholson K. .

Institution

Comprehensive Pain Program, Toronto Western Hospital, Canada. angela.mailis@uhn.on.ca

Title

Nondermatomal somatosensory deficits: overview of unexplainable negative sensory phenomena in chronic pain patients. [Review]

Source

Current Opinion in Anaesthesiology. 23(5):593-7, 2010 Oct.

Abstract

PURPOSE OF REVIEW: To review the literature and our current understanding of nondermatomal somatosensory deficits (NDSDs) associated with chronic pain in regards to their prevalence, assessment and clinical presentation, cause and pathophysiology, relationship with conversion disorder and psychological factors, as well as their treatment and prognosis.

RECENT FINDINGS: NDSDs are negative sensory deficits consisting of partial or total loss of sensation to pinprick, light touch or other cutaneous modalities. Although they had been noted more than a century ago and appear prevalent in chronic pain populations, they are poorly studied. They may be very mild or very dense, may occupy large body areas, are often highly dynamic and changeable or, to the contrary, very stable and long lasting. NDSDs may occur in the absence of biomedical pathology or coexist with structural musculoskeletal or nervous system abnormalities. They appear to be associated with psychological factors and a poor prognosis for response to treatment and return to work. Recent brain imaging studies provide a basis for understanding NDSD pathophysiology.

SUMMARY: NDSDs represent prevalent phenomena associated with chronic pain. Further, research is needed to elucidate their origin, response to treatment, and prevalence in the general population, primary care settings, and nonpain patients.

PubMed Link: http://www.ncbi.nlm.nih.gov/pubmed/20657277