CTS is caused by compression of the median nerve as it travels across the wrist with the tendons between the carpal bones and the flexor retinaculum (also know as the transverse carpal ligament):
Compression an injury to the median nerve causes numbness and tingling mostly affecting the thumb, index finger, middle finger, and half of the ring finger.
More severe cases also cause weakness and wasting of the muscle at the base of the thumb that abducts the thumb away from the fingers (abductor pollicis brevis or APB):
In severe cases, the numbness can seem to affect the whole hand, and can even radiate up the forearm and arm:
Symptoms are often worse typing, driving, and frequently wake the affected patient up at night:
CTS can usually be diagnosed on clinical grounds. A helpful physical finding is a tingling in the wrist and fingers caused by a tap over the carpal tunnel (Tinel’s sign):
In some cases, an electrodiagnostic study may be necessary to confirm the diagnosis:
CTS is usually “idiopathic” (we don’t know why it happened), but some cases are caused by diabetes, pregnancy, thyroid disease, joint swelling from rheumatoid arthritis, heavy manual work and work with vibrating tools.
Treatment usually begins with conservative measures, like avoiding exacerbating activities, and wearing a neutral position night splint:
Patients who do not improve with these conservative measures can undergo a surgical procedure to release the compressed median nerve:
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However, it is important to recognize that similar symptoms and signs can be caused by injury or compression of the sciatic nerve outside the spine, either in the buttock or thigh.
The sciatic nerve is the longest and widest nerve in the body, extending from the spine all the way to the foot, and contributes most of the nerve supply to the leg:
Sciatic nerve injury presents with:
1. Numbness affecting the entire leg, aside from the front of the thigh.
2. Weakness of the hamstrings, and all movement at the ankle.
3. Absent ankle jerk.
Sciatic Nerve Injury in the Buttock:
The nerve can be injured by misplaced buttock injections, gunshot wounds and knife injury. Buttock injections should be given in the upper outer quadrant to avoid the sciatic nerve
The sciatic nerve injury can also be injured by prolonged sitting on a toilet seat, either from direct nerve compression or hemorrhage and compartment syndrome into the gluteal muscles. This has been reported in cases of severe prolonged diarrhea, or drug induced coma on the toilet, so called toilet seat neuropathy.
Sciatic Nerve Injury at the Hip:
Sciatic nerve injury occurs in as many as 1%–3% of patients who undergo total hip replacement surgery, usually from a stretch injury to the nerves, but occasionally from a misplaced crew, broken piece of wire, fragment of bone or cement pressing on the nerve:
This presents with buttock tenderness and pain, radiate down the posterior thigh. Symptoms are made worse by prolonged sitting, bending at the waist, and activities involving hip adduction and internal rotation. The pain can be reproduced by deep palpation over the sciatic notch.
Diagnostic modalities such as CT, MRI, ultrasound, and EMG may all be normal in piriformis syndrome, but are still useful for excluding other conditions.
Magnetic resonance neurography is a specialized imaging technique which can confirm the presence of sciatic nerve irritation or injury of the sciatic nerve in the piriformis muscle.
Conservative treatment can include medications, physical therapy and stretching, or injection of a paralysing agent such as botulinum toxin into the piriformis muscle under ultrasound or CT control. Surgery may be necessary for recalcitrant cases.
However, the only treatment that has been shown to be effective for diabetic neuropathy is improved control of blood sugar.
While many patients and their doctors rely on the glycosylated hemoglobin to measure how well their diabetes is controlled, it is important to recognize that this is an average measure of blood glucose levels, and patients with mild diabetes can have peaks (which are neurotoxic) and troughs (which can also be harmful), which average each other out, leading to a “normal” glycosylated hemoglobin level , and a false sense of security that everything is OK.
If you have diabetic neuropathy, we suggest that you check your finger stick glucose regularly and write the numbers down in a book or on a computer spreadsheet, so that you can review them with your doctor.
We usually suggest the following schedule to our patients:
Pick the same 2 days each week (no matter what you have eaten those days) to do the test. On those days, check a “fasting” sugar when you first wake up (should be <130, ideally <110), a second sugar test before dinner (should be <130, ideally <110), and a third test 2 hours after dinner (should be <180, ideally <140).
Remember, although improved blood sugar control will prevent progression of your neuropathy, it won’t make it better, so start today before things get too bad!
This post is provided courtesy of K. T. Weber, Drexel University College of Medicine Class of 2013:
When a patient goes under anesthesia, a highly trained team of people take over and monitor the body. This team controls breathing, circulation and many other processes, filling in very well for the patient’s brain… however, there is one function that cannot be replicated by the anesthesia team: movement. In order to undergo surgery, a patient must have their muscles relaxed, and therefore will not move away from sore or painful spots. It is normal for people to fidget, rearranging their weight to more comfortable positions, which helps to prevent bed sores (decubitus ulcers) as well as preventing minor nerve compression.
Decubitus (or “pressure”) ulcers can be a devastating complication for patients who undergo very prolonged surgeries – Superman actor Christopher Reeve actually died from complications associated with an infected pressure ulcer. Fortunately, these wounds are very rare in patients who are only temporarily relaxed for surgery, and there are many precautions in place to prevent this from occurring.
However, minor nerve injury is still possible! One of the less commonly discussed side effects of having surgery, this minor nerve injury can be very disconcerting and affects a surprisingly large number of people
Nerve damage can occur in several forms based on the type and cause of injury:
The mildest form of nerve injury is neurapraxia, where the myelin sheath and support cells around the nerve are damaged (frequently by excessive pressure or ischemia), leading to poor signal conduction along an otherwise unharmed nerve. Neurapraxia improves on it’s own with time as the myelin sheath regenerates, and does not directly involve injury to the axon of the nerve.
Neurotmesis, the most severe type of injury, occurs when a nerve is lacerated, over-stretched or very badly crushed, and the two ends of nerve are actually separated from each other. These nerve injuries will not get better on their own without nerve graft repair surgery.
Axonotmesis is an intermediate type of nerve injury, where the nerve is damaged (often by crushing) but the support cells around the nerve are intact and aid regeneration, so (slow) spontaneous recovery is possible.
The most common symptom of compressive nerve injury is numbness or pain. The tingling, pins-and-needles feeling of hitting one’s funny bone is a classic example of nerve pain. Many patients who have undergone surgery and are held in one position for an extended period of time may wake up with areas on their skin that feel extra sensitive, like a sunburn. It is understandable to be concerned by waking up with hyperaesthesia, or pain in response to something that wouldn’t normally be painful! Weakness and uncoordination is less common, and only occurs after more severe or prolonged nerve compression during surgery.
The good news for patients who wake up with an unusually sensitive area or some numbness after having surgery is that this minor nerve damage tends to improve rapidly. Neurapraxia resolves as the swelling and bruise around the nerve decreases and the cells that help conduction recover, sometimes as quickly as a few hours, sometimes as slowly as several months. If necessary, non-steroidal anti-inflammatories, other medications for neuropathic pain and splinting can help treat the symptoms of mild nerve damage. Even more severe forms of nerve injury can recover with time – peripheral nerves grow back around 1mm per day! In the most extreme cases, without the potential to regenerate on their own with time, nerve graft repair can be discussed as an option.
Watch a video presentation on nerve injury and repair:
Of course, an ounce of prevention is worth a pound of cure. The skilled members of the operating room staff take extensive measures to protect their patients with adequate padding and careful positioning.
Numbness and tingling is one of the most common reasons for a visit to the neurologist, and it is usually the pattern or distribution of the numbness that is the key to figuring out the diagnosis:
1. Numbness in the hands:
This is most often caused by carpal tunnel syndrome (CTS). CTS is caused by median nerve compression at the wrist(s), and will usually present with numbness and tingling in one or both hands, mostly affecting the thumb, index and middle fingers (but sometimes the whole hand), worse at night or with certain wrist positions like driving, typing or holding a book, and alleviated by vigorously shaking the hand. In severe cases, there can be weakness or wasting of the muscles at the base of the thumb. Most patients can be treated conservatively with a neutral position wrist splint, but severe or recalcitrant cases will require surgery.
Ulnar neuropathy at the elbow (funny bone) can also cause numbness and tingling in the hand, usually mostly affecting the ring and little fingers, worse at night or when leaning on the elbow. Severe cases can be associated with wasting of the muscles between the knuckles and clawing of the hand. Mild cases can be treated with an elbow pad, but severe cases will necessitate surgery to decompress or transpose (move) the nerve.
2. Numbness in one foot:
A plantar neuroma is caused by injury and scar tissue, and causes pain and numbness between the toes, worse with weight bearing and walking, and usually responds to a local injection, although occasionally needs surgical excision. Tarsal tunnel syndrome, sometimes thought of as the lower extremity equivalent of carpal tunnel syndrome, results from compression of the tibial nerve at the ankle, and causes pain and numbness in the sole of the foot, worse from standing and walking. Symptoms sometime improve with orthotics, but rarely necessitate surgical decompression. Numbness in one foot can occasionally be seen from lumbar radiculopathy,but then will be usually be associated with back pain and sciatica.
3. Numbness in both feet:
So called “glove and stocking” or length-dependent numbness indicates numbness, tingling, and (in some cases) burning pain in the distal extremities usually from axonal polyneuropathy. The diagnosis can be confirmed by electrodiagnostic testing and/or skin biopsy. The most common cause is diabetes. Treatment is aimed at the underlying process, such as controlling the blood glucose in diabetics, scrupulous foot care to prevent painless injuries, and medications for symptomatic treatment of neuropathic pain.
4. Numbness in one thigh:
This is usually from meralgia paresthetica, which results from compression of the lateral femoral cutaneous nerve in the groin, and causes numbness and burning pain the the lateral thigh. It can be triggered by weight gain, weight loss or tight fitting clothes, and usually resolved spontaneously, although recalcitrant cases can be treated with a nerve block.
5. Numbness in both legs:
Numbness in both legs that comes up on to the waste in a sensory level usually indicates spinal cord lesion, and can be of acute onset in transverse myelitis, spinal cord infarction or disc herniation, or more chronic onset from multiple sclerosis, spinal cord tumor, or vitamin deficiency.
Piriformis syndrome from compression of the sciatic nerve in the buttock is rare cause of “sciatica”, and is frequently misdiagnosed as radiculopathy. Affected patients complain of pain in the buttock that radiates down the back of the leg, made worse by sitting or wearing a wallet in the affected back pocket, and relieved by standing and walking. Many patients improve with therapy and exercise, but some require nerve blocks or decompressive surgery.
7. Numbness on one side:
Numbness that affects the face, arm and leg on the same side of the body usually indicates a brain lesion on the opposite side. Sudden onset one sided numbness can indicate a stroke. More gradual onset numbness on one side can indicate multiple sclerosis or a brain tumor. Affected patients will need to undergo a brain imaging study, and treatment will depend on the underlying cause.
In the past disease modifying treatments for relapsing-remitting MS all needed to be delivered by injection, and many patients went untreated because of fear of needles, or because of injection site reactions or other side effects with each dose of the mediction, sometimes felt to be worse than symptoms from the underlying disease.
Fingolimod was approved by the FDA in Sept 2010, based studies showing less brain lesions on serial imaging studies, and reduced rates of clinical relapses and progression of disability in patients treated with the drug compared to those on placebo and interferon beta. Patients starting fingolomid do need heart rate monitoring after their first dose, eye exams at basele and after 3 months to detect macular edema (a rare side effect of the drug), and zoster vaccination for those who are not already immune.
Teriflunomide showed less brain lesions on serial imaging studies and reduced clinical relapse rates compared to placebo in clinical trials. The most common side effects were diarrhea, abnormal liver tests, nausea, and hair loss. Treated patients need liver function tests at basleine and periodically during treatment.
Unoftunately, we don’t have head-to-head trials directly comparing the efficacy of these two drugs.
So which drug would I choose? Well, I might be more inclined to recommend teriflunomide for patients with a history of cardiac arythmia or for those taking blood pressure medications such as propranolol or verapamil which can also lower the heart rate. I might be more inclined to use fingolimod in patients who taking other drugs that can affect the liver.
Neither drug is approved for use during pregnancy, although teriflunomide has a stronger warning (category X) of teratogenicity from the FDA.
In sum, we now have two oral medications available for MS patients who have previously been unable or too afraid to get treated with an injectable medication, and this can only continue to improve the long term prognosis for this disease.