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Neurologic Pathologies of the Hand
Melinda McMillen: Jordan Utley & Jenn Ostrowski
Section 1 Introduction to the Pathology
Incidence of the Pathology
There are numerous neurologic pathologies involving the hand and the most
common of these are nerve compression syndromes. The most prevalent of these
conditions include carpal tunnel syndrome (CTS), ulnar neuropathy (UN), and radial
tunnel syndrome (RTS) involving the median, ulnar, and radial nerves respectively.
CTS is often seen in women between ages 30 and 50. UN is less common than
CTS and is frequently seen in baseball pitchers (Steinberg, 2012). Signs and symptoms of
different types of neuropathy are seen in 20% of all diabetic patients (Weisberg, Garcia,
Strub).
Etiology
Compression of the nerves can result from trauma, disease or compression by
surrounding tissues and can happen anywhere along the nerves path from spinal cord
down the arm. Predisposing factors for nerve compression syndromes in the hand include
pregnancy, rheumatoid arthritis, diabetes, alcoholism, renal failure and genetic defects
(Weisberg, Garcia, Strub).
Carpal tunnel syndrome can be caused by activities or jobs where repetitive
flexion and extension of the wrist is regular. Most cases are idiopathic. In cubital tunnel
syndrome the entrapment of the ulnar nerve occurs at the elbow and is most often caused
by leaning on the elbow or by excessive elbow flexion. In cases of radial tunnel
syndrome the more likely MOI is constant use of the arm and repetitive motion of the
elbow and wrist such as twisting, gripping, pushing and pulling can stretch and irritate the
radial nerve (Steinberg, 2012).
<Photo 1: Etiology>
Section 2 Anatomy & Physiology of the Injury
Anatomy
The three peripheral nerves that provide motor and sensory input to the hand are the
median, ulnar and radial nerves.
Median Nerve
The median nerve is a branch of the medial and lateral cords of the brachial
plexus. It follows the flexor digitorum superficialis muscle down the forearm and travels
through the lateral side of the carpal tunnel in the wrist. Then it splits into motor and
palmar branches. It provides sensation to the thumb, index, middle and half of the 4th
finger and provides the ability to grasp an object with the thumb and forefinger.
Ulnar nerve
The ulnar nerve is a branch of the medial cord of the brachial plexus. This nerve
is superficial and travels on the medial palmar aspect of the wrist as it passes through the
Tunnel of Guyon, which is formed by the pisiform and hamate carpal bones. In the hand
it divides into a superficial and deep branch. This nerve innervates the little finger and
half of the ring finger and allows wrist and finger flexion.
Radial nerve
The radial nerve is a branch of the posterior cord of the brachial plexus. The nerve
runs along the lateral side of the elbow where the nerve passes into the radial tunnel,
formed by muscles and bone. Passing through the tunnel the radial nerve runs below the
supinator muscle where is divides into the superficial and deep branches. The superficial
branch provides sensation to the skin on the dorsal aspect of the hand while the deep
branch allows wrist and finger extension (Starkey, Brown, Ryan, 2010, pg
761)(Peripheral Nerve System).
<Photo 2: Anatomy>
<Photo 3: Anatomy>
Physiology
Nerve compression syndromes, as the name suggests, are caused by the nerve
becoming compressed by surrounding tissues other than a problem with the nerve itself.
The nerves innervating the hand can become entrapped many different ways and each is
specific to the individual nerve.
The median nerve is often compressed as it passes beneath the transverse carpal
ligament. This can be from inflammation, repetitive motions or genetically smaller
tunnels in the wrist (Weisberg, Garcia, Strub).
The ulnar nerve is most likely compressed at the elbow causing cubital tunnel
syndrome but can also be injured in the wrist at the Tunnel of Guyon by the pisiform and
hamate. These bones, with repetitive actions and superficial placement, can compress the
ulnar nerve (Guardia at al, 2013).
The radial nerve can be entrapped at the elbow as it twists around the humerus.
This can cause weakness in the wrist and cause drop wrist syndrome. The extensor
muscles in the hand are not able to function causing the hand to stay in a “dropped”
position (Weisberg, Garcia, Strub).
<Photo 4: Physiology>
Section 3 Evaluation of the Injury
Signs and Symptoms
The most common symptom in nerve pathologies in the hands is paresthesias,
which is a prickly, tingling sensation. The location of the symptoms will correlate with
the specific nerve that is being entrapped. This will, also, be consistent with muscle
weakness. For example, if the radial nerve is involved the patient will present with
difficulty extending the wrist (Steinberg, 2012).
<Photo 5: Signs and Symptoms>
Special Tests: Defining Practice Evaluation
Tinel’s sign is the preferred special test for all three nerve pathologies. It is
performed by tapping over the nerve to reproduce the paresthesia symptoms. Phalen’s
test is also used for suspected carpal tunnel. This is performed by the patient flexing both
wrist and pushing the dorsal side of the hands together in front of their chest and holding
this for one minute.
The most important information is found while taking a patient history. This will
pinpoint the exact location of the symptoms, which will clarify which nerve is involved.
For example numbness in the dorsal aspect of the hand is indicative of ulnar nerve
entrapment at the elbow when numbness on the palmar aspect of the hand indicates
impingement at the Tunnel of Guyon. An accurate history will, also, indicating if any
trauma or accident caused the symptoms. This is important because tingling and pain in
the hands can also be brought on by injury to the upper arm or the cervical spine and a
further examination is needed in such cases (Starkey, Brown, Ryan, 2010 pg 784, 805).
<Photo 6: Phalen’s test>
<Photo 7: Tinel’s test>
<Video 1: Tinel’s sign>
Section 4 Associated differential diagnoses
Because the structures of the wrist and hand are so close together it is critical to
obtain enough details in the history and examination to know the exact location of
symptoms.
All three nerves that innervate the hand travel down the full length of the arm and
can become entrapped at anytime. Most commonly at the elbow and wrist. Even though it
is the same nerve and may have similar symptoms they are two different diagnosis and
treatments whether the nerve is compressed at the elbow or wrist. There can be many
types of differential diagnoses and that is why taking an accurate history is crucial.
One example is radial tunnel syndrome at the wrist and elbow may present
similarly but are treated differently and it is paramount in differentiating between the two
by noticing if the pain radiates up the forearm then the nerve is compressed at the elbow.
Another example is cubital tunnel syndrome and ulnar nerve compression. They
both affect the ulnar nerve but the first is located at the elbow and the later at the wrist.
They are differentiated by the presence of sensory deficits just on the dorsal aspect of the
hand or if they are present proximal to the wrist as well (Steinberg, 2012).
Section 5 Prognosis & Recent Evidence Informing Best Clinical Care
Prognosis
Prognosis is improved the sooner treatment is started once the symptoms appear.
If 6 months of conservative treatment such as rest, splints and anti-inflammatory does not
alleviate pain or if muscle weakness is severe, surgery is recommended. Specifically
considering carpal tunnel syndrome recurrence following surgery is rare. The majority of
patients experience a full recovery (Carpal Tunnel Syndrome Fact Sheet, 2013).
<Photo 8: Prognosis>
Recent Research
A case study published 2013 in Journal of Surgical Case Reports gives detail into
something that has not been published before. It is titled “Ulnar nerve compression in
Guyon’s canal: MRI does not always have the answer”. The authors explained they had a
patient who presented with all the symptoms of ulnar nerve compression in his wrist but
the MRI imaging was inconclusive. Lipoma in the Tunnel of Guyon is rare and in their
literature search they only found 6 case studies. In all of the articles “surgical excision of
the lipoma led to good relief of ulnar nerve symtoms”. They believed in “treating the
patient not the scan” so they decided to perform surgery and found a lipoma in the canal
and removed it leading to positive results as the previous case studies.
Paget, James., Patel, Neil., Manushakian, Jacob. (2013). Ulnar nerve compression in
Guyon’s canal: MRI does not always have the answer. Journal of Surgical Case
Reports. Retrieved June 22, 2013, from
http://jscr.oxfordjournals.org/content/2013/1/rjs043.full.pdf+html
References
Carpal Tunnel Syndrome Fact Sheet. (June, 2013). National Institute of Neurological
Disorders and Stroke. Retrieved June 22, 2013, from
http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm
Guardia, Charles F III, MD et al. (February 2013). Ulnar Neuropathy. Retrieved June 21,
2013, from http://emedicine.medscape.com/article/1141515-overview#a0101
Peripheral Nerve System. John Hopkins Medicine. Retrieved June 21, 2013, from
http://www.hopkinsmedicine.org/neurology_neurosurgery/specialty_areas
/peripheral_nerve_surgery/conditions/peripheral_nerve_system.html
Starkey, C., Brown, S., Ryan, J. (2010). Examination of Orthopedic and Athletic Injuries
(3rd ed.). Philidelphia, PA: F.A. Davis Company.
Steinberg, David R. MD. (February 2012). Nerve Compression Syndromes. Retrieved
June 21, 2013, from
http://www.merckmanuals.com/professional/musculoskeletal_and_connect
ive_tissue_disorders/hand_disorders/nerve_compression_syndromes.html
Weisberg, LA., Garcia, C., Strub, R. Diseases of the Peripheral Nerves and Motor
Neurons. Retrieved June 21, 2013, from
http://tulane.edu/som/departments/neurology/programs/clerkship/uploa
d/wch16.pdf