December 2004 PES Bulletin

Foot Drop a Problem in Porphyric PN

Foot drop can be associated with a variety of conditions including peripheral neuropathy associated with acute porphyria.
Some porphyria patients may have their foot drop due to drug toxicities or diabetes which often co-exists with acute intermittent porphyria.
While most foot drop in porphyria is neurologic in nature, there are three main divisions of foot drop.
These division of foot drop include: (1) neurologic, (2) muscular, and (3) anatomic. These causes may overlap.
Treatment for foot drop can be variable and is directed at the specific cause.
Foot drop can be defined as a significant weakness of ankle and toe dorsiflexion. The foot and ankle dorsiflexors include the tibialis anterior, extensor hallucis longus, and extensor digitorum longus.
These muscles help the body clear the foot during swing phase and control plantar flexion of the foot on heel strike.
Weakness in this group of muscles results in a steppage gait.
The steppage gait, happens because the patient tends to walk with an exaggerated flexion of the hip and knee to prevent the toes from catching on the walking surface during swinging phase.
During the course of gait, the force of heel strike exceeds body weight, and the direction of the ground reaction vector passes behind the ankle and knee center. The foot will drag.
From an orthopaedic viewpoint, this causes the foot to plantar flex. When this happens, if it is left uncontrolled, it will slap the walking surface.
In a healthy person, the anterior tibialis, which controls plantar flexion, absorbs the shock of heel strike.
Injury to the dorsiflexors, or to any point along the neural pathways that supply them, can result in foot drop.
Peroneal neuropathy which is caused by compression at the fibular head, is the most common compressive neuropathy in the lower extremity. Foot drop is the chief symptom.
Foot drop also may be seen as a combination of neurologic, muscular, and anatomic dysfunction.
Neurological causes of foot drop include mononeuropathies of the deep peroneal, common peroneal, or sciatic nerves.
Functional recovery can be achieved over a prolong duration time.Bracing of the affected ankle can be undertaken, thus avoiding surgery.

Ralph Reginbald PA
Orthropaedics & Rehabilitative Medicine

Confusion Usually Present in Attacks

Call it what you will, whether it be confusion, mental dysfunction, encephalopathy or disorientation, or the collective term, mental change. Such mental change usually present during an acute attack of porphyria.
Confusion is a term which best describes want most porphyria patients are faced with during the onset of an acute attacks, and especially when they have to wait to being infusion therapy.
As carbohydrate levels dwindle, and vomiting or diarrhea get underway, levels of confusion increase.
Confusion is an inability to think with customary speed or clarity. Such confusion in a porphyria patient is marked by some degree of lack of focus of attention and disorientation.
Confusion is generally characterized by a look of wonderment or being puzzler, lack of attention, and inability to make decisions.
Unfortunately some porphyria patients while confused, may behave aggressively.
Confusion, may come on suddenly or gradually over time, but most often wil disappear as the porphyria attack is treated.
It is always necessary to have the electrolytes checked to be sure that balance is restored.
Causes of confusion can include any of the following: Alcohol intoxication, Low blood sugar (hyperglycemia), Fluid and electrolyte imbalance, seizures, nutritional deficiencies, particularly niacin deficiency, Vitamin C deficiency, or Vitamin B-12 deficiency. There can be environmental causes such as heavy metal poisoning,
In addition Drugs can cause confusion. Such drugs include: atropine, chloroquine, cimetidine, CNS depressants in large doses, cycloserine, digitalis medicines -- oral, indomethacin, lidocaine, withdrawal from narcotics and barbiturates
A porphyria patient who is confused should not be left alone.
In order to ensure a confused person's safety, physical restraints may be required in some situations.
A calm, quiet, and peaceful environment is recommended. It is a generally accepted practice for porphyria patients to have drapes closed, room temperature reduced, and indirect low lighting with no noise, scents, or unnecessary visitors present in the room.
When medical staff or visitors enter the patient's room, one should always introduce themselves during every encounter with the confused person.
Placing a calendar and clock near the confused person can help keep him or her oriented.
Care givers should frequently re-orient the confused person. It is important to talk to the patient and confirm their location, time of day or night and what is going on.

Dr. Kenneth Carlson
Neuropsychiatric

Sensory Loss Present in Acute Porphyria

Sensory loss in porphyria can be identified by many of its characteristics. Such characteristics include the waxing and waning of numbness and tingling ablong the peripheral nerves.
Numbness and tingling are abnormal sensations that are usually felt along the extremities in normally healthy people briefly. In acute porphyria patients numbness and tingling can become very familiar conditions.
Numbness is a complete lack of sensation or lack of response to something normally painful.
Tingling is an indication of damage or irritation to the nerves.
Unlike numbness, tingling suggests that the affected nerve is not completely dead or severed, just injured or experiencing pressure.
Unless the cause is obvious (for example, when a hand or foot "falls asleep" because of the position it is in), you should discuss any numbness and tingling with your physician. Keeps notes in regard to local, and duration, as well as the type of sensation.
Besides acute porphyria itself or other metabolic abnormalities, there can be other causes for numbness and tingling.
There can be toxic action on nerves which can include the effects of lead, alcohol and tobacco.
One may have effects of diabetes, hypothyroidism, both which are associated with acute porphyria.
Many prescription drugs are know to cause sensory loss.
Drugs known to cause sensory loss include: Chemotherapeutic agents; Chloroquine; D-penicillamine; Isoniazid; Nitrofurantoin; Parenteral gold therapy and Phenytoin. Other medical condition known for causing sensory loss include: Multiple sclerosis; Seizures; and Migraines. Diagnostic tests may be performed to identify the cause and extent of sensory loss.

Mary Jo Simpson MSN, FNP
Neurology

Muscle Cramps and Spasms in Porphyria

Often accompanying painful deep bone pain, peripheral neuropathy, numbness and tingling, in acute porphyria, there can be muscle cramping and spasms.
Muscle cramps are involuntary and often painful contractions of the muscles which produce a hard, bulging muscle.
Fasciculation or muscle twiching, is the result of spontaneous local muscle contractions that are involuntary and typically only affect individual muscle groups connected to a particular motor neuron.
Fortunately fasciculation does not cause pain, but it often occurs while other PN associated conditions persist which are often very painful.
Ordinary muscle cramps are common even in normally healthy persons. These muscle cramps or spasms may be stopped by stretching the affected muscle.
The majority of spasms or muscle cramps are minor and often go unnoticed. Some are common and normal, while others indicate a neurologic disorder such as peripheral neuropathy associated with porphyria.
Spasms will occur due to a variety of causes including dehydration, hypothyroidism, heavy exercise and muscle fatigue. The use of some medications will also cause spasms.
In the acute porphyrias most muscle cramping has been found to be associated with low levels of calcium and magnesium. Magnesium levels can easily be depleted in porphyria during acute crises. Calcium also can become depleted. Other metabolic abnormalities can also can such depletion.
More serious causes of muscle cramping and spasms can be that of motor neuron disease, muscle diseases, or denervation.
In porphyria the cause is usually directed related to the porphyria and the presence of peripheral neuropathy.
When severe muscle cramping occurs it is usually accompanied by weakness and atrophy of the affected muscle group as well as other signs and symptoms.
Treatment of such muscle crampimg includes stetching of the muscles, and massage.
If the cramping continues, use of cyclobenzaprine to control muscle contractions patients has often been prescribed safely for porphyria patients.
Physicians will prescribe analgesics for the control of pain accompanying the spasms if muscle relaxants are unable to control spasms activity.

Robert Johnson M.D.
Internal Medicine
Retired clinician