Health Scan: Backs bear a heavy burden

TAU researchers say nerve damage, specifically nerves that travel through neck, shoulders is also a serious risk.

By
April 2, 2013 01:57
Lower back pain.

Lower back pain 370. (photo credit: Wikimedia Commons)

Trudging from place to place with heavy weights on our backs is an everyday reality for many people – from schoolchildren toting textbooks in backpacks to firefighters and soldiers carrying equipment they require in their work. Muscle and skeletal damage are very real concerns.

Now Tel Aviv University researchers say that nerve damage, specifically to the nerves that travel through the neck and shoulders to animate our hands and fingers, is also a serious risk.

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Prof. Amit Gefen of TAU’s biomedical engineering department and Prof. Yoram Epstein of the university’s Sackler Faculty of Medicine, along with PhD student Amir Hadid and Dr. Nogah Shabshin of Assuta Medical Center, have determined that the pressure of heavy loads carried on the back has the potential to damage the soft tissues of the shoulder, causing microstructural damage to the nerves.

The result could be anything from simple irritation to diminished nerve capacity, ultimately limiting the muscles’ ability to respond to the brain’s signals, inhibiting movement of the hand and the dexterity of the fingers. In practice, this could impact functionality, reducing a worker’s ability to operate machinery, compromising a soldiers’ shooting response time or limiting a child’s writing or drawing capacity. The research was published in the Journal of Applied Physiology.

Focusing their study on combat units in which soldiers must carry heavy backpacks, the researchers discovered that, in addition to complaining of discomfort or pain in their shoulders, soldiers also reported tickling sensations or numbness in the fingers.

Exploring this issue in a noninvasive manner, they used biomechanical analysis methods originally developed for investigating chronic wounds. The analyses show how mechanical loads, defined as the amount of force or deformation placed on a particular area of the body, were transferred beneath the skin to cause damage to tissue and internal organs.

Based on data collected by MRI scans, Gefen and Epstein developed anatomical computer models of the shoulders. These showed how pressure generated by the weight of a backpack load is distributed beneath the skin and transferred to the brachial plexus nerves. The models also account for mechanical properties, such as the stiffness of shoulder tissues and the location of blood vessels and nerves in the sensitive areas which are prone to damage.

Extensive mechanical loading was also seen to have a high physiological impact.

“The backpack load applies tension to these nerves,” explained Gefen. He noted that the resulting damage “leads to a reduction in the conduction velocity – that is, the speed by which electrical signals are transferred through the nerves.” With a delay or reduction in the amplitude or intensity of signals, nerve communication cannot properly function, he said.

These results apply to people from all walks of life, said Gefen.

Many professions and leisure activities, such as hiking or traveling, involve carrying heavy equipment on the back. The researchers plan to extend this study in two directions – to study the effects of loading on nerve conductivity and to examine the impact of these heavy loads on children’s bodies.

School bags are a major concern, he warned. It cannot be assumed that children’s bodies react to shoulder stress in exactly the same way as adults. Differences in physiology could lead to different consequences, tolerance and damage levels.

LEARNING FROM MASS CATASTROPHES

In the ongoing effort to achieve optimal preparedness for disasters, the conducting of a structured “after-action review” process is of utmost importance. A recent article in the American Journal of Emergency Medicine describes the process of scientifically developing a structured tool for such a process in emergency departments following a mass casualty incident.

This process was led by Ben- Gurion University of the Negev’s Dr. Bruria Adini, an emergency medicine expert and author of several other validated tools that assess preparedness. The current study was conducted by masters students in emergency medicine.

The students, who are also senior staff in various level 1 hospitals, chose this topic for research as they had personally experienced the need for such a tool.

Bringing in their personal knowledge, they conducted an extensive literature review among experts and finally tested the tool during a simulated earthquake drill. The study was successful in producing a practical tool that has already been approved and adopted by the Health Ministry’s emergency and disaster management division. The tool includes specific guidelines regarding when and how to use it.

Dr. Limor Aharonson-Daniel, chairman of the Beersheba university’s emergency medicine department and the PREPARED Center for Emergency Response Research, said this study is a great example of the fruitful collaboration between academia and the field, a partnership that was recently formalized in an agreement between BGU and the ministry. She was very pleased that the students – Tami Greenberg, Fabiana Eden, Tami Chen and Tali Ankri – managed to introduce an important change during their studies.

The significance of the tool goes beyond the immediate assessment as it not only facilitates learning lessons regarding emergency response, it also enables ventilation of feelings, thus mitigating anxieties and expediting a speedy return to normalcy.

“The publication of this study in this prestigious journal may be a vehicle for international application of the findings of this study in other healthcare systems,” says Adini.

GOING UNDER

The Royal College of Anesthetists and the Association of Anesthetists of Great Britain and Ireland have published in the journal Anesthesiaa initial findings on how many surgical patients experienced accidental awareness during general anesthesia.

The survey asked senior anesthetists in UK hospitals to report how many cases of accidental awareness during general anesthesia they encountered in 2011.

About three million general anesthetics are administered in UK hospitals each year.

Although previous reports claimed to have found a surprisingly high incidence of awareness, about one in 500 general anesthetics, the new report found it to be much less common in the UK. The researches found only one episode out of every 15,000 patients put under general anesthesia.

Oxford University Prof. Jaideep Pandit commented, “Anesthesia is a medical specialty very much focused on safety and patient experience. We identified accidental awareness during anesthesia as something that concerns patients and the profession.... We are particularly interested in patient experiences of awareness.

Although we know that some patients do suffer distress after these episodes, our survey has found that the vast majority of episodes are brief and do not cause pain or distress.”

University of Bath Prof. Tim Cook added: “Risks to patients undergoing general anaesthesia are very small and have decreased considerably in the last decades....While our findings are generally reassuring for patients and doctors alike, we recognize that there is still more work to be done.”


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