- Email: [email protected]
DIAGNOSIS OF THE CARPAL TUNNEL SYNDROME
854
cigarette smoking," I infection, 12 fluid overload, or anticoagulant therapy’3 is usually present. The finding that haemorrhage may occur within hours of reexposure to cigarette smoke"is intriguing in view of the known effect of cigarette smoke on the permeability of the pulmonary epithelium.’4 Various collagen vascular diseases and types of vasculitis can be associated with alveolar haemorrhage. In systemic lupus this is an unusual manifestation but carried a mortality of more than 70% in the reports reviewed by Leatherman et a1.5 In systemic vasculitis episodes of alveolar haemorrhage are more common. In one case of alveolar haemorrhage in Wegener’s granulomatosis the involved lung showed a necrotising alveolar "capillaritis", while typical histological changes of Wegener’s granulomatosis were found only in a localisedcavitating lesion. Other reported associations include systemic sclerosis,16 rheumatoid arthritis,17 Henoch-Schonlein purpura, 18 polyarteritis nodosa,s and mixed connective-tissue disease.19 In idiopathic rapidly progressive glomerulonephritis alveolar haemorrhage may occur early, when renal function is normal. The histology of the lung shows no underlying mechanism for the haemorrhage since there is no vasculitis and immunofluorescence tests are
negative. Exogenous causes are penicillamine,2O
of alveolar haemorrhage trimellitic anhydride,21 and lymphangiography.22 In the cases related to penicillamine the dose has usually been high (750-2000 mg/day) and the course prolonged (over ten months). Leatherman et als stress the favourable response to high doses of corticosteroids in acute, life-threatening alveolar haemorrhage. There is no evidence that such treatment affects the longer term course of idiopathic pulmonary haemosiderosis, but immunosuppressants may. Therapy may need to be supplemented by cyclophosphamide in Wegener’s granulomatosis and by plasmapheresis and immunosuppression in Goodpasture’s syndrome. In the latter, precipitating factors such as infections and fluid overload should be dealt with and smoking discouraged with exceptional vigour. 11
Donaghy M, Rees AJ. Cigarette smoking and lung haemorrhage in glomerulonephritis caused by autoantibodies to glomerular basement membrane. Lancet 1983; ii. 1390-93
AJ, Lockwood CM, Peters DK. Enhanced allergic tissue injury in Goodpasture’s syndrome by intercurrent bacterial infection. Br Med J 1977; ii: 723-26. Kincaid-Smith P, d’Apice AJF Plasmapheresis in rapidly progressive glomerulonephritis. Am J Med 1978; 65: 564-66. Jones JG, Minty BD, Lawler P, Hulands G, Crawley JCW, Veall N. Increased alveolar epithelial permeability in cigarette smokers Lancet 1980; i: 66-67. Stokes TC, McCann BG, Rees RT, Sims EH, Harrison BDW. Acute fulminating intrapulmonary haemorrhage in Wegener’s granulomatosis. Thorax 1982; 37:
1 2 Rees
13. 14 15
315-16. 16 Kallenbach J, Prinsloo I, Zwi S Progressive systemic sclerosis complicated by diffuse pulmonary haemorrhage. Thorax 1977; 32: 767-70. 17. Smith BS. Idiopathic pulmonary haemosiderosis and rheumatoid arthritis. Br Med J 1966; i. 1403-04. 18 Kathuria S, Chejfec G Fatal pulmonary Henoch-Schönlein syndrome Chest 1982; 82:
DIAGNOSIS OF THE CARPAL TUNNEL SYNDROME CHRONIC entrapment neuropathy is common and that involving the median nerve at the wrist is probably the most frequently encountered. So it is surprising that the carpal tunnel syndrome was not widely recognised as a major cause of pain and dysaesthesiae in the hand until the 1950s.1 Patients typically have nocturnal pain, paraesthesiae, and numbness involving the median-innervated fingers which awaken them. The pain often radiates up the arm towards or even beyond the elbow. Relief is obtained by shaking the hand. Weakness is a less frequent complaint. These symptoms may also occur during the day, particularly if unaccustomed exercise has been undertaken such as wringing out wet clothes, sewing, or knitting. Both hands can be involved but the dominant one is usually affected to the
greater
extent.
Carpal tunnel syndrome is associated with pregnancy and with various systemic disorders including hypothyroidism, rheumatoid arthritis, acromegaly, and amyloid. Previous Colles fracture also predisposes to its development, as does peripheral neuropathy. There is some evidence that patients with carpal tunnel syndrome have small carpal tunnels,2 and many of the associated conditions either increase the bulk of the contents of the carpal tunnel or narrow the canal. Vascular engorgement of tissue and flexion of the wrist, trapping the nerve against the proximal edge of the carpal ligament, probably account for the nocturnal exacerbation of
symptoms.3 Experimentally, carpal tunnel syndrome can be induced in guineapig, and this has supplemented the sparse human pathological material, leading to a better understanding of the pathophysiology. Demyelination of fibres occurs as the myelin lamellae break away from the paranodal region and retract owing to compression.45 A striking symmetry of the lesion is seen at the upper and lower portions of the carpal ligament, the retraction of myelin being in opposite directions. These demyelinated fibres can remyelinate. In addition wallerian degeneration occurs in many fibres, leading to regeneration clusters of spouting axons passing down a single Schwann cell tube. Extensive endoneurial and to a lesser extent perineurial fibrosis also occurs, resulting in fascicular enlargement. Ischaemia does not play a part in the development of these abnormalities, but certainly contributes
the
to
the
pain.6
Diagnosis of carpal tunnel syndrome rests upon the clinical story, signs,- and electrophysiological testing. Examination may reveal some wasting of abductor policis brevis with weakness best assessed by having the patient abduct the thumb at right angles to the plane of the palm, a procedure that renders the long abductor and extensor of the thumb ineffective. Sensory testing is often normal but there may be a superficial sensory impairment in the median-innervated digits, especially the index finger. Assessment of two-point discrimination is
"splits"
the
a
useful sensory test: the sensory loss often never happens with
ring finger, something that
654-56 19 Leatherman
M, Gilliatt RW, Golding JSR, Wilson JG Acroparaesthesiae in the carpal tunnel syndrome Lancet 1953; ii: 590-95. 2. Dekel S, Coates R. Primary carpal stenosis as a cause of "idiopathic" carpal tunnel syndrome Lancet 1979; ii: 1024. 3. Phalen GS. Reflection on twenty one years experience with the carpal tunnel
20
4. Marotte LR. An
21 22.
JW, Sibley RK, Davies SF Diffuse intrapulmonary hemorrhage and glomerulonephritis unrelated to anti-glomerular basement membrane antibody. Am J Med 1982 72: 401-10 Sternlieb I, Bennett B, Scheinberg IH. Penicillamine induced Goodpasture’s syndrome in Wilson’s Disease. Ann Intern Med 1975; 82: 673-76. Herbert FA, Orford R. Pulmonary hemorrhage and edema due to inhalation of resins containing trimellitic anhydride Chest 1979; 76: 546-51. Marglin SI, Castellino RA Severe pulmonary haemorrhage following lymphography. Cancer 1979, 43: 482-83
1. Kremer
5. 6.
syndrome. JAMA 1970; 212: 1365-67. electron microscope study of chronic median nerve compression in the guinea pig. Acta Neuropathol (Berlin) 1974; 27: 69-82 Neary D, Ochoa J, Gilliatt RW. Subclinical entrapment neuropathy in man.J Neurol Sci 1975; 24: 283-98. Fullerton PM. The effect of ischaemia on nerve conduction in carpal tunnel syndrome J Neurol Neurosurg Psychiatry 1963; 26: 385-97.
855 lesions of the brachial plexus or cervical roots. Tinel’s sign, induced by tapping the wrist just below the carpal ligament, is said to occur in three-quarters of the patients’-an overestimate in all probability. Electrophysiological testing is important for three reasons. Firstly, it will help to clinch the diagnosis, especially in those patients with no signs or an atypical story. Secondly, it facilitates early diagnosis and operation, thereby preventing the occurrence of excessive wallerian degeneration. Thirdly, it is useful in assessing the patient who returns to the clinic for a
second
opinion after an apparently unsuccessful operation.
It is important, however, to gain the information required with the simplest and least uncomfortable test. The simplest test involves a supramaximal stimulation of the median nerve at the wrist and measurement of the distal latency for motor units in abductor policis brevis.’ The latency is prolonged in some patients, owing to demyelination and regeneration of the motor fibres, but it is normal in a substantial proportion with proven carpal tunnel syndrome. Sensory action potentials are abnormal in a higher proportion. They are customarily recorded by either stimulating a medianinnervated digit, usually the second, and recording the response from the wrist proximal to the carpal- ligament (orthodromic response8) or vice versa (antidromic response9). In carpal tunnel syndrome the sensory action potential is small and its peak is commonly delayed because of slow conduction in demyelinated or regenerated nerve fibres and a reduction in their total number. Comparison of the amplitude of the median nerve sensory action potential with that obtained from ulnar nerve stimulation, the former usually being the larger, is useful both to exclude generalised neuropathy and to clarify the occasional case where the median sensory action potential is small but still within the normal range. While it is difficult to know how often a patient with carpal tunnel syndrome is not correctly diagnosed with a combination of the above tests, the Copenhagen school have shown that near-nerve needle recordings detect additional cases. 10,1 With this technique the lowest velocities are obtained in the median nerve between the palm and the wrist and a change at this segment may be the only abnormality demonstrable in carpal tunnel syndrome. Since this segment of the median nerve, which primarily contains sensory fibres, can be stimulated transcutaneously, it is possible that the action potential recorded from the wrist will be abnormal in a greater proportion of patients with carpal tunnel syndrome than is the case with conventional digital stimulation-in which case the expensive, technologically demanding, and uncomfortable invasive techniques will be needed less often. To this end Mills has reportedl2 a series of 72 hands from 47 patients with a tentative diagnosis of carpal tunnel syndrome in which he compares conventional sensory action potential recordings obtained from stimulation of the second digit (median) and fifth digit (ulnar) with stimulation of the median and ulnar nerves in the palm, recording in all cases at the
7
8 9 10
Simpson JA. Electrical signs in the diagnosis of carpal tunnel and related syndromes. J Neurol Neurosurg Psychiatry 1956; 19: 275-80. Gilliatt RW, Sears TA Sensory nerve action potential in patients with peripheral nerve lesions JNeurol Neurosurg Psychiatry 1958; 21: 109-18. Mavor H, Schiozawa R. Antidromic digital and palmar nerve action potentials. Electroenceph Clin Neurophysiol 1971; 30: 210-21. Buchthal F, Rosenfalk A, Trojaborg W Electrophysiological findings in entrapment of the median nerve at wrist and elbow. J Neurol Neurosurg Psychiatry 1974; 37:
wrist. He found that the peak latency of the response was abnormal in 53% of hands on digital stimulation compared with 67% of hands on palmar stimulation. All but one of the hands with an abnormal digital sensory action potential had an abnormal palm-to-wrist sensory action potential. Unfortunately he does not let us know how many patients were abnormal. Interestingly, 6 patients had an abnormal ulnar sensory action potential: in 5 of these there was a significantly greater slowing of conduction in the median nerve fibres and it was assumed that they all had carpal tunnel syndrome. The abnormality in the ulnar nerve was thought to be due to low hand temperature in these 5 patients; the other patient had diabetes. Mills’ data suggest that transcutaneous palmar stimulation of the median nerve is at least as good at detecting carpal tunnel syndrome as conventional digital stimulation or recording and that the technique is rapid, easily applied, and not too uncomfortable. The data that have yet to be obtained concern the false-positive rate of such a test. As Mills says, the only way to determine this "is a careful follow-up of all operated and unoperated cases". We await his report.
AGEING IN DOWN’S SYNDROME DOWN’S syndrome is known to be due to a complete or partial trisomy of chromosome 21. The way in which an excess of chromosome material results in the syndrome remains undetermined. The characteristic clinical picture is one of growth deficiency, abnormal morphogenesis, and mental retardation. The facial appearance, the shape of the head, and the abnormal posture and gait, are very familiar.
There is
increased risk of autoimmune disease, diabetes and mellitus, thyroiditis, and a high incidence of malignant disease. Premature senility is also characteristic1 especially in the central nervous system.2There is a decline in the already impaired intellectual capacity from an early age,3and at necropsy there are distinctive changes of senile dementiasenile plaques, Alzheimer’s neurofibrillary degeneration, and Sincowitz’s granulovacuolar degeneration of nerve cells.44 Wisniewski et al5 and Takashima and Becked have in addition described basal ganglia calcification. The disturbances in growth and development, being evident from early embryogenesis, are likely to be attributable directly to the presence of the extra chromosome and to interference in the normal pattern of genetically programmed growth and differentiation. It is possible that the premature senility and high incidence of age-related problems are extensions of the same process, an explanation that would be in keeping with the theory that ageing normally
proceeds along 1.
to palm and from palm to wrist the carpal tunnel syndrome.J Neurol Neurosurg Psychiatry 1971, 34: 243-52. 12 Mills KR Orthodromic sensory action potentials from palmar stimulation in the diagnosis of carpal tunnel syndrome. J Neurol Neurosurg Psychiatry 1985; 48:
3. 4.
5.
in
250-55
a
genetically predettrmined
Jervis GA. Premature senility
in
Down’s
559-61. 2. Malamud N
340-60. 11 Buchthal F, Rosenfalk A. Sensory conduction from digit
an
6
syndrome.
Ann NY Acad Sci
course.
1970;
171:
Neuropathology of organic brain syndromes associated with ageing. In. Gaitz CM, ed. Ageing and the brain New York: Plenum Press, 1972: 63-87. Dalton AJ, Crapper DR, Schlotterer GR. Alzheimer’s disease in Down’s syndrome: visual retention deficits. Cortex 1974; 10: 366-77. Crapper DR, Dalton AJ, Skopitz M, Scott JW, Hachinski VC. Alzheimer degeneration in Down’s syndrome: electrophysiologic alterations and histopathologic findings Arch Neurol 1975, 33: 618-23 Wisniewski KE, French JH, Rosen JF, Kozlowski PP, Tenner M, Wiscniewski HM. Basal ganglia calcification (BGC) in Down’s syndrome (DS)—another manifestation of premature ageing. Ann NY Acad Sci 1982; 396: 179-89. Takashima S, Becker LE. Basal ganglia calcification in Down’s syndrome. J Neurol Neurosurg Psychiatry 1985;
48: 61-64
cigarette smoking," I infection, 12 fluid overload, or anticoagulant therapy’3 is usually present. The finding that haemorrhage may occur within hours of reexposure to cigarette smoke"is intriguing in view of the known effect of cigarette smoke on the permeability of the pulmonary epithelium.’4 Various collagen vascular diseases and types of vasculitis can be associated with alveolar haemorrhage. In systemic lupus this is an unusual manifestation but carried a mortality of more than 70% in the reports reviewed by Leatherman et a1.5 In systemic vasculitis episodes of alveolar haemorrhage are more common. In one case of alveolar haemorrhage in Wegener’s granulomatosis the involved lung showed a necrotising alveolar "capillaritis", while typical histological changes of Wegener’s granulomatosis were found only in a localisedcavitating lesion. Other reported associations include systemic sclerosis,16 rheumatoid arthritis,17 Henoch-Schonlein purpura, 18 polyarteritis nodosa,s and mixed connective-tissue disease.19 In idiopathic rapidly progressive glomerulonephritis alveolar haemorrhage may occur early, when renal function is normal. The histology of the lung shows no underlying mechanism for the haemorrhage since there is no vasculitis and immunofluorescence tests are
negative. Exogenous causes are penicillamine,2O
of alveolar haemorrhage trimellitic anhydride,21 and lymphangiography.22 In the cases related to penicillamine the dose has usually been high (750-2000 mg/day) and the course prolonged (over ten months). Leatherman et als stress the favourable response to high doses of corticosteroids in acute, life-threatening alveolar haemorrhage. There is no evidence that such treatment affects the longer term course of idiopathic pulmonary haemosiderosis, but immunosuppressants may. Therapy may need to be supplemented by cyclophosphamide in Wegener’s granulomatosis and by plasmapheresis and immunosuppression in Goodpasture’s syndrome. In the latter, precipitating factors such as infections and fluid overload should be dealt with and smoking discouraged with exceptional vigour. 11
Donaghy M, Rees AJ. Cigarette smoking and lung haemorrhage in glomerulonephritis caused by autoantibodies to glomerular basement membrane. Lancet 1983; ii. 1390-93
AJ, Lockwood CM, Peters DK. Enhanced allergic tissue injury in Goodpasture’s syndrome by intercurrent bacterial infection. Br Med J 1977; ii: 723-26. Kincaid-Smith P, d’Apice AJF Plasmapheresis in rapidly progressive glomerulonephritis. Am J Med 1978; 65: 564-66. Jones JG, Minty BD, Lawler P, Hulands G, Crawley JCW, Veall N. Increased alveolar epithelial permeability in cigarette smokers Lancet 1980; i: 66-67. Stokes TC, McCann BG, Rees RT, Sims EH, Harrison BDW. Acute fulminating intrapulmonary haemorrhage in Wegener’s granulomatosis. Thorax 1982; 37:
1 2 Rees
13. 14 15
315-16. 16 Kallenbach J, Prinsloo I, Zwi S Progressive systemic sclerosis complicated by diffuse pulmonary haemorrhage. Thorax 1977; 32: 767-70. 17. Smith BS. Idiopathic pulmonary haemosiderosis and rheumatoid arthritis. Br Med J 1966; i. 1403-04. 18 Kathuria S, Chejfec G Fatal pulmonary Henoch-Schönlein syndrome Chest 1982; 82:
DIAGNOSIS OF THE CARPAL TUNNEL SYNDROME CHRONIC entrapment neuropathy is common and that involving the median nerve at the wrist is probably the most frequently encountered. So it is surprising that the carpal tunnel syndrome was not widely recognised as a major cause of pain and dysaesthesiae in the hand until the 1950s.1 Patients typically have nocturnal pain, paraesthesiae, and numbness involving the median-innervated fingers which awaken them. The pain often radiates up the arm towards or even beyond the elbow. Relief is obtained by shaking the hand. Weakness is a less frequent complaint. These symptoms may also occur during the day, particularly if unaccustomed exercise has been undertaken such as wringing out wet clothes, sewing, or knitting. Both hands can be involved but the dominant one is usually affected to the
greater
extent.
Carpal tunnel syndrome is associated with pregnancy and with various systemic disorders including hypothyroidism, rheumatoid arthritis, acromegaly, and amyloid. Previous Colles fracture also predisposes to its development, as does peripheral neuropathy. There is some evidence that patients with carpal tunnel syndrome have small carpal tunnels,2 and many of the associated conditions either increase the bulk of the contents of the carpal tunnel or narrow the canal. Vascular engorgement of tissue and flexion of the wrist, trapping the nerve against the proximal edge of the carpal ligament, probably account for the nocturnal exacerbation of
symptoms.3 Experimentally, carpal tunnel syndrome can be induced in guineapig, and this has supplemented the sparse human pathological material, leading to a better understanding of the pathophysiology. Demyelination of fibres occurs as the myelin lamellae break away from the paranodal region and retract owing to compression.45 A striking symmetry of the lesion is seen at the upper and lower portions of the carpal ligament, the retraction of myelin being in opposite directions. These demyelinated fibres can remyelinate. In addition wallerian degeneration occurs in many fibres, leading to regeneration clusters of spouting axons passing down a single Schwann cell tube. Extensive endoneurial and to a lesser extent perineurial fibrosis also occurs, resulting in fascicular enlargement. Ischaemia does not play a part in the development of these abnormalities, but certainly contributes
the
to
the
pain.6
Diagnosis of carpal tunnel syndrome rests upon the clinical story, signs,- and electrophysiological testing. Examination may reveal some wasting of abductor policis brevis with weakness best assessed by having the patient abduct the thumb at right angles to the plane of the palm, a procedure that renders the long abductor and extensor of the thumb ineffective. Sensory testing is often normal but there may be a superficial sensory impairment in the median-innervated digits, especially the index finger. Assessment of two-point discrimination is
"splits"
the
a
useful sensory test: the sensory loss often never happens with
ring finger, something that
654-56 19 Leatherman
M, Gilliatt RW, Golding JSR, Wilson JG Acroparaesthesiae in the carpal tunnel syndrome Lancet 1953; ii: 590-95. 2. Dekel S, Coates R. Primary carpal stenosis as a cause of "idiopathic" carpal tunnel syndrome Lancet 1979; ii: 1024. 3. Phalen GS. Reflection on twenty one years experience with the carpal tunnel
20
4. Marotte LR. An
21 22.
JW, Sibley RK, Davies SF Diffuse intrapulmonary hemorrhage and glomerulonephritis unrelated to anti-glomerular basement membrane antibody. Am J Med 1982 72: 401-10 Sternlieb I, Bennett B, Scheinberg IH. Penicillamine induced Goodpasture’s syndrome in Wilson’s Disease. Ann Intern Med 1975; 82: 673-76. Herbert FA, Orford R. Pulmonary hemorrhage and edema due to inhalation of resins containing trimellitic anhydride Chest 1979; 76: 546-51. Marglin SI, Castellino RA Severe pulmonary haemorrhage following lymphography. Cancer 1979, 43: 482-83
1. Kremer
5. 6.
syndrome. JAMA 1970; 212: 1365-67. electron microscope study of chronic median nerve compression in the guinea pig. Acta Neuropathol (Berlin) 1974; 27: 69-82 Neary D, Ochoa J, Gilliatt RW. Subclinical entrapment neuropathy in man.J Neurol Sci 1975; 24: 283-98. Fullerton PM. The effect of ischaemia on nerve conduction in carpal tunnel syndrome J Neurol Neurosurg Psychiatry 1963; 26: 385-97.
855 lesions of the brachial plexus or cervical roots. Tinel’s sign, induced by tapping the wrist just below the carpal ligament, is said to occur in three-quarters of the patients’-an overestimate in all probability. Electrophysiological testing is important for three reasons. Firstly, it will help to clinch the diagnosis, especially in those patients with no signs or an atypical story. Secondly, it facilitates early diagnosis and operation, thereby preventing the occurrence of excessive wallerian degeneration. Thirdly, it is useful in assessing the patient who returns to the clinic for a
second
opinion after an apparently unsuccessful operation.
It is important, however, to gain the information required with the simplest and least uncomfortable test. The simplest test involves a supramaximal stimulation of the median nerve at the wrist and measurement of the distal latency for motor units in abductor policis brevis.’ The latency is prolonged in some patients, owing to demyelination and regeneration of the motor fibres, but it is normal in a substantial proportion with proven carpal tunnel syndrome. Sensory action potentials are abnormal in a higher proportion. They are customarily recorded by either stimulating a medianinnervated digit, usually the second, and recording the response from the wrist proximal to the carpal- ligament (orthodromic response8) or vice versa (antidromic response9). In carpal tunnel syndrome the sensory action potential is small and its peak is commonly delayed because of slow conduction in demyelinated or regenerated nerve fibres and a reduction in their total number. Comparison of the amplitude of the median nerve sensory action potential with that obtained from ulnar nerve stimulation, the former usually being the larger, is useful both to exclude generalised neuropathy and to clarify the occasional case where the median sensory action potential is small but still within the normal range. While it is difficult to know how often a patient with carpal tunnel syndrome is not correctly diagnosed with a combination of the above tests, the Copenhagen school have shown that near-nerve needle recordings detect additional cases. 10,1 With this technique the lowest velocities are obtained in the median nerve between the palm and the wrist and a change at this segment may be the only abnormality demonstrable in carpal tunnel syndrome. Since this segment of the median nerve, which primarily contains sensory fibres, can be stimulated transcutaneously, it is possible that the action potential recorded from the wrist will be abnormal in a greater proportion of patients with carpal tunnel syndrome than is the case with conventional digital stimulation-in which case the expensive, technologically demanding, and uncomfortable invasive techniques will be needed less often. To this end Mills has reportedl2 a series of 72 hands from 47 patients with a tentative diagnosis of carpal tunnel syndrome in which he compares conventional sensory action potential recordings obtained from stimulation of the second digit (median) and fifth digit (ulnar) with stimulation of the median and ulnar nerves in the palm, recording in all cases at the
7
8 9 10
Simpson JA. Electrical signs in the diagnosis of carpal tunnel and related syndromes. J Neurol Neurosurg Psychiatry 1956; 19: 275-80. Gilliatt RW, Sears TA Sensory nerve action potential in patients with peripheral nerve lesions JNeurol Neurosurg Psychiatry 1958; 21: 109-18. Mavor H, Schiozawa R. Antidromic digital and palmar nerve action potentials. Electroenceph Clin Neurophysiol 1971; 30: 210-21. Buchthal F, Rosenfalk A, Trojaborg W Electrophysiological findings in entrapment of the median nerve at wrist and elbow. J Neurol Neurosurg Psychiatry 1974; 37:
wrist. He found that the peak latency of the response was abnormal in 53% of hands on digital stimulation compared with 67% of hands on palmar stimulation. All but one of the hands with an abnormal digital sensory action potential had an abnormal palm-to-wrist sensory action potential. Unfortunately he does not let us know how many patients were abnormal. Interestingly, 6 patients had an abnormal ulnar sensory action potential: in 5 of these there was a significantly greater slowing of conduction in the median nerve fibres and it was assumed that they all had carpal tunnel syndrome. The abnormality in the ulnar nerve was thought to be due to low hand temperature in these 5 patients; the other patient had diabetes. Mills’ data suggest that transcutaneous palmar stimulation of the median nerve is at least as good at detecting carpal tunnel syndrome as conventional digital stimulation or recording and that the technique is rapid, easily applied, and not too uncomfortable. The data that have yet to be obtained concern the false-positive rate of such a test. As Mills says, the only way to determine this "is a careful follow-up of all operated and unoperated cases". We await his report.
AGEING IN DOWN’S SYNDROME DOWN’S syndrome is known to be due to a complete or partial trisomy of chromosome 21. The way in which an excess of chromosome material results in the syndrome remains undetermined. The characteristic clinical picture is one of growth deficiency, abnormal morphogenesis, and mental retardation. The facial appearance, the shape of the head, and the abnormal posture and gait, are very familiar.
There is
increased risk of autoimmune disease, diabetes and mellitus, thyroiditis, and a high incidence of malignant disease. Premature senility is also characteristic1 especially in the central nervous system.2There is a decline in the already impaired intellectual capacity from an early age,3and at necropsy there are distinctive changes of senile dementiasenile plaques, Alzheimer’s neurofibrillary degeneration, and Sincowitz’s granulovacuolar degeneration of nerve cells.44 Wisniewski et al5 and Takashima and Becked have in addition described basal ganglia calcification. The disturbances in growth and development, being evident from early embryogenesis, are likely to be attributable directly to the presence of the extra chromosome and to interference in the normal pattern of genetically programmed growth and differentiation. It is possible that the premature senility and high incidence of age-related problems are extensions of the same process, an explanation that would be in keeping with the theory that ageing normally
proceeds along 1.
to palm and from palm to wrist the carpal tunnel syndrome.J Neurol Neurosurg Psychiatry 1971, 34: 243-52. 12 Mills KR Orthodromic sensory action potentials from palmar stimulation in the diagnosis of carpal tunnel syndrome. J Neurol Neurosurg Psychiatry 1985; 48:
3. 4.
5.
in
250-55
a
genetically predettrmined
Jervis GA. Premature senility
in
Down’s
559-61. 2. Malamud N
340-60. 11 Buchthal F, Rosenfalk A. Sensory conduction from digit
an
6
syndrome.
Ann NY Acad Sci
course.
1970;
171:
Neuropathology of organic brain syndromes associated with ageing. In. Gaitz CM, ed. Ageing and the brain New York: Plenum Press, 1972: 63-87. Dalton AJ, Crapper DR, Schlotterer GR. Alzheimer’s disease in Down’s syndrome: visual retention deficits. Cortex 1974; 10: 366-77. Crapper DR, Dalton AJ, Skopitz M, Scott JW, Hachinski VC. Alzheimer degeneration in Down’s syndrome: electrophysiologic alterations and histopathologic findings Arch Neurol 1975, 33: 618-23 Wisniewski KE, French JH, Rosen JF, Kozlowski PP, Tenner M, Wiscniewski HM. Basal ganglia calcification (BGC) in Down’s syndrome (DS)—another manifestation of premature ageing. Ann NY Acad Sci 1982; 396: 179-89. Takashima S, Becker LE. Basal ganglia calcification in Down’s syndrome. J Neurol Neurosurg Psychiatry 1985;
48: 61-64