Nervous System Involvement in Systemic Sclerosis

The nervous system comprises the brain and various types of nerves that carry impulses from all parts of the body such as the heart, stomach and intestines and convey appropriate responses to the muscles and all of the organs in the body.

One of the major components of the nervous system is the autonomic nervous system that has two arms: (1) sympathetic and, (2) parasympathetic nervous systems. The sympathetic arm of the autonomic nervous system is the one responsible for the flight and fight response to stress by increasing the heart rate for example in contrast, the parasympathetic system works by slowing down the heart rate and helps in digesting and absorbing food. Therefore, any alteration in the autonomic nervous system will disrupt this fine balance control of sympathetic and parasympathetic systems. In Systemic Sclerosis, autonomic abnormalities are now known to affect the heart and bowel. The latter involves the nerve supply to the muscles of the gullet causing heartburn, while damage to the nerve endings of the anal wall may cause incontinence. In the heart, rhythm disturbances from interruption to the nerve fibres may give rise to palpitations and dizzy spells. Such disturbances rarely lead to significant symptoms and therefore do not require any specific treatment. (Proton pump inhibitors such as Losec or Domperidone are very effective drugs to relieve heartburn and swallowing difficulties).

 

One of the most frequently reported neurological features is carpal tunnel syndrome in which the median nerve, the nerve that runs along with the finger tendons in the wrist to supply the sensation and small muscles of the hand, is compressed by the surrounding soft tissue in the wrist. This typically occurs in the early phase of the diffuse form of scleroderma when there is significant inflammation and swelling of soft tissue in the wrist area. This may cause shooting pain over the affected hand with numbness and tingling. Patients quite often note that they wake up at night with the pins and needles and having to shake their hand to gain some relief. It may be occasionally difficult to distinguish these symptoms from Raynaud’s Phenomenon. To confirm the diagnosis, a thorough physical examination by your clinician is necessary and in some cases, a nerve conduction study may be helpful. There are other treatable causes of carpal tunnel syndrome and these will need to be assessed by your clinician. In severe cases, weakness of the hand muscles may occur.

 
Our experience reveals that in a majority of those affected, the symptoms would abate with time as the skin disease improves. Most will respond with conservative measures such as a wrist splint at night. Anti-inflammatory tablets, if not contraindicated, can be helpful. If these measures do not alleviate the symptoms, steroid injections into the affected area are often used. It is not unusual to experience an increase in the intensity of the pain shortly after the injection but taking prophylactic analgesia at that time may prevent this. The symptoms should then gradually improve over the next few days following the injection. In severe cases an operation may be necessary. This would necessitate a small longitudinal incision across the wrist. Rarely other nerves of the hand may be compressed and this underlies the importance of keeping a close watch of these symptoms in patients with early disease.


Another common and characteristic neurological feature in Scleroderma is trigeminal neuropathy. This nerve has three divisions and is responsible for the detection of sensory changes over the forehead and eye (V1), cheek (V2) and lower face and jaw (V3) as shown in the diagram. It detects facial touch, pain and temperature, as well as controlling the muscles for chewing. This is characterised by sudden attacks of pain that are typically brief, lasting for a few seconds to two minutes. These attacks may be severe and are described as intense, stabbing or electric shock-like. It typically occurs only on one side affecting the upper, middle and/or lower portions of the face. Each attack may occur spontaneously or be triggered by trivial stimuli such as a light touch, or a gust of wind brushing against the face. Other common triggers include chewing, drinking, hair combing or tooth brushing. Occasionally, these acute exacerbations may become more frequent and more severe while the period of remissions becomes shorter. In such cases, an aching pain or subtle numbness may develop over the affected area.

 

Medications are the first line of treatment for trigeminal neuropathy. Nowadays, the most effective drug used for this complication includes some of the agents used for epilepsy but at lower doses. They probably work by reducing the hyperactivity of the nerve in the brain. In severe and chronic cases, neurosurgical decompressive approach may be used but it may be difficult to predict who will benefit from the various techniques available.

There are very few reports of mini-strokes and cognitive alterations in scleroderma and it is suggested there may be additional factors unrelated to the usual risk factors associated with strokes in the general population contributing to this complication in Scleroderma. Brain imaging has demonstrated reduced blood flow in the affected areas of the brain.

In conclusion, there is now increasing awareness among patients and clinicians alike that neurological consequences of scleroderma are not all that uncommon but it is reassuring, in most instances, that conservative measures and simple medications are adequate to treat the symptoms.

Dr Voon H Ong, Research Registrar, Royal Free Hospital.