DOI: 10.1093/brain/awh017 Advanced Access publication November 7, 2003 Brain (2004), 127, 193±202 Coexistent hereditary and in¯ammatory neuropathy

Lionel Ginsberg,1,2 Omar Malik,2 Anthony R. Kenton,4 David Sharp,2 John R. Muddle,2 Mary B. Davis,3 John B. Winer,4 Richard W. Orrell1,2 and Rosalind H. M. King1

1University Department of Clinical Neurosciences, Royal Correspondence to: Dr L. Ginsberg, Department of Free and University College Medical School, University Neurology, Royal Free Hospital, Pond Street, College London, 2Department of Neurology, Royal Free London NW3 2QG, UK

Hospital, 3Neurogenetics Laboratory, Institute of E-mail: [email protected] Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021 Neurology, London and 4Birmingham Neuroscience Centre, Queen Elizabeth Hospital, Birmingham, UK

Summary Classically, the course of Charcot±Marie±Tooth (CMT) modulatory treatment. In¯ammatory neuropathy has disease is gradually progressive. We describe eight atyp- previously been recognized in patients with hereditary ical patients who developed acute or subacute deterior- neuropathy, with uncharacterized genetic defects and ation. Seven of these had genetically proven CMT with CMT1B. We present detailed assessments of disease type 1A (CMT1A) due to 17p11.2± patients with CMT1A and CMTX, including 12 duplication, and one had X-linked disease (CMTX) biopsy, and conclude that coexistent in¯ammatory neu- due to a mutation in the GJB1 gene. In this group there ropathy is not genotype-speci®c in hereditary motor was suf®cient clinical, electrophysiological and neuro- and sensory neuropathy. Although this was not a formal pathological information to indicate a diagnosis of a epidemiological study, estimates of the prevalence of superimposed in¯ammatory polyneuropathy. The age CMT disease and chronic in¯ammatory demyelinating range of the patients was 18±69 years, with a mean of polyneuropathy indicate that the association is more 39 years. A family history of a similar neuropathic con- frequent than would be expected by chance. This has dition was present in only four patients. All eight had implications for understanding the pathogenesis of an acute or subacute deterioration following a long in¯ammatory neuropathies and raises important consid- asymptomatic or stable period. Seven had neuropathic erations in the management of patients with hereditary pain or prominent positive sensory symptoms. Nerve neuropathies. If a patient with CMT disease experiences biopsy demonstrated excess lymphocytic in®ltration in an acute or subacute deterioration in clinical condition, all eight patients. Five patients were treated with ster- treatment of a coexistent in¯ammatory neuropathy with oids and/or intravenous immunoglobulin, with variable steroids or immunoglobulin should be considered. positive response; three patients received no immuno-

Keywords: Charcot±Marie±Tooth disease; chronic in¯ammatory demyelinating polyneuropathy; peripheral nerve; nerve biopsy; neuropathy

Abbreviations: CIDP = chronic in¯ammatory demyelinating polyneuropathy; CMT = Charcot±Marie±Tooth; CMT1A = Charcot±Marie±Tooth disease type 1A; CMT1B = Charcot±Marie±Tooth disease type 1B; CMTX = X-linked Charcot± Marie±Tooth disease; MCV = motor nerve conduction velocity; MPZ = zero gene; PMP22 = peripheral myelin protein 22; SAP = sensory nerve action potential

Introduction Until the last quarter of the twentieth century there was polyneuropathy (CIDP). With the advent of validated clinical signi®cant uncertainty in the classi®cation of the chronic and electrophysiological criteria for the hereditary motor and demyelinating neuropathies. Thus, many patients given a sensory neuropathies (Harding and Thomas, 1980) followed generic diagnosis of hypertrophic interstitial neuropathy by the advances in molecular analysis of the last decade, most (Thomas et al., 1975) undoubtedly had a hereditary neuro- patients with a genetic basis for their neuropathy can now be pathy when a family history was lacking. Others would now given a ®rm and speci®c diagnosis (Boerkoel et al., 2002). be diagnosed as having chronic in¯ammatory demyelinating Similarly, strict criteria now exist for the diagnosis of CIDP,

Brain Vol. 127 No. 1 ã Guarantors of Brain 2003; all rights reserved 194 L. Ginsberg et al. emphasizing neurophysiological measurements (Ad Hoc for all patients listed as having a ®nal diagnosis of CMT disease. As Subcommittee of the American Academy of Neurology it is not routine practice to biopsy patients with a classical CMT AIDS Task Force, 1991). syndrome, we deduced that these patients were in some way Even before the developments in the molecular genetics of atypical. They may have been biopsied because CMT disease had , however, there was evidence that this not been suspected beforehand, presumably in the absence of a separation of hereditary causes from CIDP was sometimes family history. Alternatively, patients with known CMT disease may too rigid: there were patients who apparently had both have been biopsied because of an unusual disease course. Either way, the selected patients were judged likely to be a fertile source for conditions. Thus, individuals were identi®ed who had the the present study. Seventeen patients were identi®ed initially. Of phenotype of Charcot±Marie±Tooth (CMT) disease and a these, ®ve were eliminated because of incomplete molecular genetic positive family history, yet were steroid-responsive (Dyck information. The remainder all had CMT1A due to the chromosome Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021 et al., 1982; Bird and Sladky, 1991). With the arrival of 17p11.2±12 duplication, apart from the one patient with a GJB1 molecular techniques, it has proved possible to classify such mutation. Another four patients were excluded through lack of patients according to genotype, notably for mutations in the clinical and/or pathological data (only patients whose nerve biopsies myelin protein zero (MPZ) gene (Donaghy et al., 2000). had been subject to immunocytochemical analysis in addition to Indeed, it has recently been suggested that coexistent standard histological techniques were included). Of the remaining in¯ammation in CMT disease may be genotype-speci®c to patients (seven CMT1A and one CMTX), the majority were the type 1B disease (CMT1B) due to MPZ mutations examined by at least one of the authors (L.G.); otherwise, clinical (Watanabe et al., 2002). In an immunological study of and paraclinical information was obtained from the case notes. patients with CMT1A, however, a subgroup was thought to have superimposed in¯ammation (Gabriel et al., 2002). This conclusion was based on their stepwise (as opposed to DNA analysis gradual) disease progression and, in some instances, a In all cases, the molecular genetic diagnosis was obtained using response to immunomodulatory therapy. CMT1A, an auto- DNA extracted from blood by standard methods. The chromosome somal dominant condition, is the commonest form of CMT 17p11.2±12 duplication was detected using ¯uorescent quantitative disease and is usually the result of a 1.5 Mb duplication at polymerase chain reaction (PCR) of ®ve microsatellite markers from chromosome 17p11.2±12 (Lupski et al., 1991; Raeymaekers within the 1.5 Mb duplicated region. Samples were analysed on an et al., 1991) involving the gene for peripheral myelin protein Applied Biosystems 3100 Genetic Analyser (Applied Biosystems, 22 (PMP22) (Matsunami et al., 1992; Patel et al., 1992; Foster City, CA, USA) using Genescan software (Genescan Europe AG, Freiburg, Germany). The presence of the duplication was Timmerman et al., 1992; Valentijn et al., 1992). con®rmed by the detection of three alleles at one or more marker loci Here we describe in detail a patient with proven CMT1A or by gene dosage. The GJB1 mutation was detected by sequencing due to the chromosome 17p11.2±12 duplication, who had the entire coding region of the gene (Bergoffen et al., 1993; coexistent in¯ammatory neuropathy, as evidenced by clin- Fairweather et al., 1994). ical, neurophysiological and neuropathological features and a marked positive response to treatment with intravenous immunoglobulin. This patient's presentation prompted a Neurophysiology review of our departmental diagnostic database for neuro- All patients had undergone sensory and motor nerve conduction pathies, based on nerve biopsies, which yielded six other studies in the upper and lower extremities using standard techniques patients with CMT1A who had an atypical phenotype for (Medelec Sapphire, Oxford Instruments, Woking, Surrey, UK). CMT disease, suggesting a superimposed in¯ammatory neuropathy. Finally, we report a patient with evidence of an in¯ammatory neuropathy in the context of a mutation in the gap junction protein beta 1 (GJB1) gene, the cause of X- Nerve biopsy linked CMT disease (CMTX) (Bergoffen et al., 1993). Taken Sural or radial nerve fascicular biopsies had been obtained under together, these ®ndings indicate that coexistent in¯ammation local anaesthesia from standard sites. The bulk of each patient's in CMT disease is not a particularly rare phenomenon, nor is specimen was ®xed in buffered 2.5% glutaraldehyde, postosmicated, it genotype-speci®c. Some of these results have appeared dehydrated and embedded in epoxy resin (Durcupan, Fluka, Buchs, previously in abstract form (Malik et al., 2000). A modi®ed Switzerland). Semithin sections (0.5 mm) were stained with thionine and acridine orange (Sievers, 1971). The remainder of the specimen and abbreviated version of the index case history has been was snap-frozen in liquid nitrogen. Frozen sections were stained given in an educational text based on neurological cases immunocytochemically for B lymphocytes (CD22), T lymphocytes (Ginsberg, 2001). (CD4 and CD8), early macrophage marker (CD68) and late macrophage product (Mac387). Image analysis was performed using a Zeiss Axioplan microscope (Zeiss UK Ltd, Welwyn Garden Methods City, Herts, UK) ®tted with an automated stage (Gerbr MaÈrzhaÈuser, Patient ascertainment oHG, Wetzlar, Germany and using KS400 imaging system (Zeiss The nerve biopsy database in the Department of Clinical UK Ltd, Welwyn Garden City, Herts, UK). All myelinated ®bres in Neurosciences at the Royal Free Hospital, London, was searched all available fascicles were counted and measured. Hereditary and in¯ammatory neuropathy 195

Results epineurial and endoneurial T-cell in®ltrates on immunostain- Index case history (case 1) ing (Fig. 2A). This 39-year-old woman had never been keen to partici- On the basis of the clinical, CSF, neurophysiological and pate in sports at school. Deformities of both feet were biopsy ®ndings, the patient was treated with intravenous noted in childhood. She ®rst came to the attention of immunoglobulin (2 g/kg over 5 days). She improved clinic- neurologists at the age of 25 years, with subacute ally (corresponding to one point on the Rankin scale), progression of her lower limb weakness associated with regaining hand function (con®rmed by quantitative myome- paraesthesiae in the feet. Her gait continued to deterior- try), and electrophysiologically. Most strikingly, partial ate, albeit more slowly, and she required surgery to both motor conduction block was no longer apparent after the therapy (Fig. 3).

feet at the age of 32 years, since which time she started Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021 She has since been stable on maintenance infusions of to wear ankle±foot orthoses. At the age of 39 years, she immunoglobulin, 2 g/kg every 5±6 weeks. With longer presented with a 1-month history of worsening weakness, intervals, her strength and sensory symptoms deteriorate. numbness and paraesthesiae of the hands. She developed dif®culty holding a cup or pen. There was no history of neck pain but she had been aware of weakness of her neck. Sphincter control was normal. Patients with CMT1A: composite analysis (cases Her previous medical history was otherwise remarkable for 1±7) a diagnosis of ulcerative colitis, made in her mid-thirties. In Clinical features her family history, several members, including her father, had These patients had a mean age at the time of nerve biopsy of a similar, but milder, neurological disorder. 39 years (range 18±69). There were four females and three Examination showed normal cognitive function. In the males. A family history consistent with autosomal dominant cranial , there was bilateral ptosis, more marked on the inheritance was present in only three cases. No patient had a left, and weakness of neck ¯exion. There was distal previous history of any general medical condition commonly symmetrical wasting and weakness of the upper and lower associated with peripheral neuropathy; in particular, none limbs. A postural tremor was present in both upper limbs. was diabetic. There was evidence of the neurological disease Tendon re¯exes were absent and plantar responses were in the ®rst decade of life in three patients and in the second in unobtainable. Sensory testing revealed impaired joint pos- two. The remainder presented in adult life. By the time of ition and vibration sense in the ®ngers and toes. Cutaneous their nerve biopsy, all patients had at least minimal evidence sensation to pin, temperature and light touch was diminished of neuropathy, i.e. loss of re¯exes, but none had a pure to the mid-forearm and knee bilaterally. She had bilateral pes classical CMT syndrome of gradually progressive distal cavus and scars of previous foot surgery. Peripheral nerves weakness, are¯exia, foot deformity and minor sensory were not thickened. involvement. All seven patients had come to nerve biopsy Routine haematological and biochemical investigations because of an acute or subacute deterioration following a long were normal. DNA analysis con®rmed the duplication at asymptomatic or stable period. Six patients had neuropathic chromosome 17p11.2±12. Tests directed to excluding the pain or prominent positive sensory symptoms. Cranial nerve remote possibility of coexistent myasthenia gravis (be- signs were noted in ®ve patients (ptosis and weakness of neck cause of the ptosis and neck weakness) were negative, ¯exion in case 1, ptosis and weakness of eye closure in case 2, including anti-acetylcholine receptor . sensorineural deafness and weakness of neck ¯exion in case Examination of the CSF showed an acellular specimen 3, patchy facial sensory impairment in case 5 and sensor- with elevated protein concentration at 0.78 g/l; the glucose ineural deafness and weakness of neck ¯exion in case 6). One concentration was normal. Oligoclonal bands were present patient (case 1) had a signi®cant upper limb postural tremor, in CSF and serum. suggesting the Roussy±LeÂvy variant of CMT disease. Two Nerve conduction studies showed marked slowing of motor patients had no detectable weakness on clinical examination. nerve conduction velocities (MCV) to 18 m/s in the median In one (case 7), this was probably simply a re¯ection of his nerve and 19 m/s in the ulnar nerve. Distal motor latencies relative youth (age 18 years) at the time of assessment and were prolonged (8.6 ms in the median nerve, 8.2 ms in the high baseline level of strength, potentially masking any minor ulnar nerve) and sensory nerve action potentials (SAP) were weakness. The other patient (case 5) was unusual, presenting absent. These ®ndings are typical of a severe demyelinating in adult life with episodes of pain and stiffness in the limbs, motor and sensory neuropathy, as seen in CMT1A. More muscle cramps, fasciculations and calf muscle hypertrophy. unusually, however, partial motor conduction block was This patient has previously been reported and more exten- detected, initially only proximally in the Erb's to elbow sively discussed (as case 56) in a series illustrating the range segment of the median nerve, but on subsequent occasions in of phenotypic manifestations of the duplication at chromo- distal segments of the median and ulnar nerves. some 17p11.2±12 (Thomas et al., 1997). Likewise, cases 2 Sural nerve fascicular biopsy con®rmed the typical and 3 of the present study correspond to cases 15 and 30 hypertrophic changes of CMT1A (Fig. 1A) but also showed respectively in that series. Regarding skeletal and other 196 L. Ginsberg et al. Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021

Fig. 1 Semithin resin sections from nerve biopsies of patients with CMT disease (thionine and acridine orange). (A) Case 1, showing widespread hypertrophic changes typical of CMT1A. The ®bres at the centres of some onion bulbs have no demonstrable myelin (arrow) (bar = 50 mm). (B) Case 7, showing extensive subperineurial oedema (asterisk) in addition to the hypertrophic changes in another CMT1A patient (bar = 100 mm). (C) Case 8, showing loss of large myelinated ®bres and effete onion bulbs (arrows) in a CMTX patient (bar = 100 mm).

features of the genetic defect, only three patients had foot deformities, in the form of pes cavus (cases 1, 3 and 7). One patient (case 6) had echocardiographic evidence of hyper- trophic cardiomyopathy. Peripheral nerve thickening was not a feature of the patients in this study.

Blood and CSF ®ndings Routine haematological and biochemical investigations were normal in all patients. In particular, none had evidence of a serum paraprotein. The results of CSF examination were available in six patients. All specimens were acellular with a normal glucose concentration. The mean protein concentra- tion was 0.87 g/l (range 0.43±1.85). Four patients had signi®cantly elevated CSF protein concentrations (>0.7 g/l). Oligoclonal bands were present in CSF and serum in one Hereditary and in¯ammatory neuropathy 197 Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021

Fig. 2 Immunostaining of frozen sections of nerve biopsies from patients with CMT disease. Each example shows T-lymphocytic in®ltration in the endoneurium and epineurium [CD4 antigen demonstrated with horseradish peroxidase (dark brown); bar = 100 mm]. (A) Case 1. (B) Case 7. (C) Case 8. patient (case 1) and only in CSF in another (case 6). In all other cases, bands were absent on CSF electrophoresis.

Neurophysiology Upper limb MCV (usually for the median nerve, recording from abductor pollicis brevis) ranged from 6 to 34 m/s (distal motor latency 6.8±8.6 ms). Values for the lower limbs were rarely obtained due to severe denervation of the small foot muscles. The SAPs were generally absent, except in case 5, where the radial and sural SAPs were obtainable (6 and 7 mV respectively), median and ulnar SAPs being absent. Partial motor conduction block was detected in three patients.

Nerve biopsy Fascicular nerve biopsy in all seven patients showed deple- tion of the myelinated ®bre population with marked loss of the largest ®bres (Fig. 4). Prominent onion-bulb hypertrophic changes were seen in all cases. Thinly myelinated ®bres were evident in six 198 L. Ginsberg et al. biopsies, suggesting remyelination or regeneration. Recent degeneration was not found in any specimen but there was (as indicated by the presence of demyelinated axons) or active evidence of axonal regeneration (clusters of axonal sprouts) demyelination was seen in four biopsies. Active axonal in six. Extensive subperineurial oedema was noted in one biopsy (case 7; Fig. 1B). Immunostaining showed prominent T-lymphocyte in®ltration in the same specimen (Fig. 2B). Lymphocytic in®ltration in excess of that seen in control sections from patients with amyloid neuropathy (where none was evident) was found in all cases.

Response to treatment Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021 Two patients received corticosteroids in the form of prednisolone (cases 3 and 4). Both responded clinically but in case 4 the response was transient and subsequent treatment with intravenous immunoglobulin was unsuccessful. Two other patients were treated with intravenous immunoglobulin (cases 1 and 2). Both responded clinically and in one (case 1, see above) this was supported by myometric and electro- physiological measurements. The other three patients (cases 5±7) did not receive immunomodulatory treatment.

Summary of atypical features in CMT1A patients Taken as a group, these patients showed several clinical and paraclinical features which were atypical for CMT disease. The presence or absence of each of these features for the seven patients is summarized in Table 1.

Patient with CMTX (case 8) This 43-year-old man had undergone corrective surgery to both ankles at the age of 13 years. Further surgery to the left foot was required 20 years later. At the age of 40 years, he developed pain and numbness in the left arm. The sensory disturbance spread to involve the right leg, then the left leg and ®nally, 1 year later, the right arm. He experienced burning sensations in the arms and stabbing pain in both lower limbs, affecting his gait. There had been two episodes of left facial numbness, each lasting 1 h. Sphincter control remained normal and there was no history of neck or back pain. In his family history, a maternal uncle was said to have had hammer toe deformities. Fig. 3 Upper limb nerve conduction studies in case 1, showing On examination, cognitive function was normal, as were partial motor conduction block in the forearm segments of the the cranial nerves, apart from a residual visual ®eld defect on right median and ulnar nerves and its reversal following treatment the left, secondary to a retinal detachment at the age of 31 with intravenous immunoglobulin. (A) Median nerve before years. There was mild distal symmetrical wasting and treatment. (B) Median nerve after treatment. (C) Ulnar nerve weakness in the upper and lower limbs. Tendon re¯exes before treatment. (D) Ulnar nerve after treatment. In each panel, the upper trace shows the compound muscle action potential were absent and plantar responses were downgoing. Sensory (recorded from abductor pollicis brevis in the median nerve study, testing showed impaired joint position sense to the ankles. abductor digiti minimi in the ulnar nerve) evoked by Vibration sensation was absent to the anterior superior iliac supramaximal stimulation at the wrist. The response to spines and to the elbows. Temperature perception was supramaximal stimulation at the elbow is shown in the lower reduced distally bilaterally to the knees and the mid forearms. trace. An amplitude reduction of 76% before treatment in the median nerve study became 22% after immunoglobulin treatment. Pin and light touch sensation were diminished to mid-thigh For the ulnar nerve study, the equivalent ®gures were 56 and 3% level. In the upper limbs, there was impairment of these respectively (corresponding to reductions in the area under the modalities of cutaneous sensation to the elbow on the right action potential curve of 63 and 8%). and to the upper arm on the left. Romberg's test was positive. Hereditary and in¯ammatory neuropathy 199

He had bilateral pes cavus and scars of previous corrective revealed numerous T cells around epineurial blood vessels surgery. There was also a scar from excision of an occipital and in the perineurium (Fig. 2C). lipoma. Peripheral nerves were not thickened. The patient was treated with intravenous immunoglobulin Routine haematological and biochemical tests were nor- (2 g/kg), with dramatic improvement in his pain and other mal. The CSF was acellular, protein concentration 0.5 g/l and sensory symptoms for a 6-week period. Unfortunately, glucose concentration normal. MRI of brain and whole spine subsequent infusions were progressively less effective and a was normal. DNA analysis excluded a duplication at trial of prednisolone was also unsuccessful. He has since been chromosome 17p11.2±12. Further molecular genetic studies treated with drugs used in the management of neuropathic revealed a Cys173Arg (TGC/CGC) mutation in the coding pain, with varying bene®t. region of the GJB1 gene, which has been described previ- ously (Inherited Peripheral Neuropathies Mutation Database Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021 online, 2003) and is likely to be pathogenic. Discussion Nerve conduction studies showed slowing of MCV to 31, As would be expected for a condition arising on a hereditary 32 and 25 m/s in the median, ulnar and peroneal nerves degenerative basis, the usual course of CMT disease is respectively. F waves were uniformly absent, as were SAPs. gradually progressive. The archetypal pattern which results is Partial motor conduction block was not detected. one of symmetrical distal muscle wasting and weakness, Sural nerve fascicular biopsy showed chronic neuropathic are¯exia, foot deformity and minor sensory abnormalities. features with prominent clumps of Schwann cells but few Considerable phenotypic heterogeneity has been reported, classical onion-bulb formations (Fig. 1C). Immunostaining however, both between and within families, for CMT1A, the commonest form of the disease (Thomas et al., 1997). The patients with CMT1A in the present study deviate from a classical CMT syndrome in several respects (Table 1). These atypical features correspond closely to those suggested by others as pointing to a coexistent in¯ammatory neuropathy (Bird and Sladky, 1991). Taken individually, the characteristics listed in Table 1 vary in their speci®city as indicators of an in¯ammatory process. Thus, in all seven patients there was a history of stepwise deterioration with acute or subacute relapses after periods of clinical stability; this would be most unusual for a classical inherited neuropathy. Similarly, all patients but one had positive sensory symptoms or neuropathic pain; this again favours an acquired in¯ammatory disorder. Elevated CSF protein values are less speci®c but the result in case 7 Fig. 4 Bar chart showing distribution of myelinated ®bre (1.85 g/l) is dif®cult to explain in any way other than an diameters. Combined data from all CMT1A patients (cases 1±7). in¯ammatory neuropathy, particularly when taken in com- The continuous line indicates normal control values (pooled from bination with the neuropathological features in his case (Figs three individuals in the same age range as the patients). The normal bimodal distribution of ®bre calibre has been lost in the 1B and 2B). Of the four patients who received immunomo- patients. dulatory therapy, persistent bene®t was observed in three cases, with only transient bene®t in the fourth. Objective

Table 1 Summary of CMT1A patients Case Age Sex Positive Step-wise Conduction Increased In¯ammatory Response (years) sensory deterioration block CSF protein* in®ltrate in to treatment symptoms biopsy

1 39 F + + + + (0.78) + + 2 25 F + + 0 0 +++ + 3 40 F 0 + + n/a +++ + 4 28 M + + + 0 + +/± 5 55 M + + 0 + (0.71) + n/g 6 69 F + + 0 + (0.99) + n/g 7 18 M + + 0 + (1.85) +++ n/g

*Values of CSF protein concentration, for patients in whom it was increased, are given in parentheses in g/l. n/a = not available; n/g = immunomodulatory treatment not given; 0 = absent; + = present; +/± = partial; +++ = marked in¯ammatory cell in®ltrate (>100 CD4 lymphocytes per section). 200 L. Ginsberg et al. evidence of bene®t is an issue but in at least one patient (case immunological study (Gabriel et al., 2002); some of these 1) the clinical impression of a positive response to intraven- patients may have had CIDP (Vallat et al., 2003). ous immunoglobulin was supported by electrophysiological Despite the caveats attached to the individual attributes data (Fig. 3). listed in Table 1, the composite picture that emerges is one of Electrodiagnostic evidence of an acquired in¯ammatory a subgroup of CMT1A patients with coexistent in¯ammatory demyelinating process is dif®cult to adduce in the context of neuropathy. This is particularly evident in the index case patients who already have marked slowing of nerve conduc- (case 1), in which all the markers of superimposed in¯am- tion velocity as a consequence of the inherited disorder. mation are positive. This patient also had a diagnosis of Indeed, the degree of slowing typically seen in CMT1 ulcerative colitis, which is associated with peripheral effectively precludes many of the electrophysiological cri- neuropathy, notably a perineuritis (Chad et al., 1986). The teria used in the diagnosis of CIDP (Ad Hoc Subcommittee of ®rst subacute deterioration in the neuropathy, however, Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021 the American Academy of Neurology AIDS Task Force, occurred years before the onset of in¯ammatory bowel 1991). The major remaining potential method of distinguish- disease and subsequent neuropathic activity was not associ- ing an acquired demyelinating neuropathy from an inherited ated temporally with relapses of colitis. disorder electrically is by measures which indicate patchy, The patient with CMTX also had evidence of a superim- multifocal nerve involvement in the former as opposed to the posed in¯ammatory process. The classical phenotype of more homogeneous features seen in hereditary disease (Lewis CMTX resembles CMT1 with the exception that slowing of and Sumner, 1982). Thus, partial motor conduction block was nerve conduction velocity is usually milder (Nicholson and observed in three CMT1A patients in the present study, in Nash, 1993). Our patient (case 8) deviates from the archetype keeping with superimposed in¯ammation, and in case 1 the in several of the characteristics listed in Table 1. Thus, he had block was reversed by immunomodulatory therapy. a subacute deterioration after a long period of stability, Nerve biopsies suffer from drawbacks in interpretation positive sensory symptoms and neuropathic pain, in¯amma- similar to those for electrodiagnostic data, many of the tory in®ltrates on nerve biopsy and a response, albeit features of acquired demyelination potentially being masked transient, to immunomodulatory therapy. This is the ®rst by the chronic changes of the hereditary disease. Some of the detailed description of coexistent in¯ammatory neuropathy in neuropathological ®ndings in our CMT1A patients suggest a CMTX, though there have been hints from electrophysiolo- superimposed in¯ammatory process, i.e. the presence of gical data that the phenomenon may occur (Tabaraud et al., in¯ammatory cell in®ltrates and endoneurial or subperineur- 1999; Gutierrez et al., 2000). ial oedema, but caution is required to avoid overinterpretation Does the evidence for an in¯ammatory neuropathy in these even of these aspects (Gabreels-Festen et al., 1993). It is cases signify anything more than the chance occurrence of perhaps noteworthy that there was evidence of active and/or CIDP in a proportion of CMT patients? Epidemiological recent demyelination in four out of seven biopsies in the studies of CIDP are few but a point prevalence of 1 in 100 000 present series, compared with only one out of 10 in the study has been quoted for a comparable general population (Lunn of the phenotypic manifestations of chromosome 17p11.2 et al., 1999). The prevalence of CMT disease as a whole has duplication cited previously (Thomas et al., 1997). The been estimated at 1 in 2500 (Skre, 1974). Applying these degree of T-lymphocyte in®ltration was marked in several of ®gures to the present study is complicated by the fact that our patients (e.g. Fig. 2). Although such in®ltrates have been some of the patients came from the region served by the reported in biopsy series of CMT disease (Gabreels-Festen Department of Clinical Neurosciences at the Royal Free et al., 1993), they are generally regarded as helpful in the Hospital, whereas others were referred from further a®eld. diagnosis of in¯ammatory neuropathy, especially when The catchment population for the department is approxi- immunocytochemical markers are used to highlight lympho- mately 2.5 million, of whom ~1000 should, therefore, have cyte subsets (Schmidt et al., 1996). The dif®culty lies in CMT disease at any given time. Of the eight patients in the determining quantitatively whether the cellular in®ltration study, four were referred from within the region, giving an exceeds that found in control biopsy specimens. Contrary to estimated prevalence of 1 in 250 for coexistent in¯ammation the ®ndings in all seven patients in the present series, no in CMT disease. This calculation does not allow for the signi®cant additional in¯ammatory in®ltration was seen in difference between point and period prevalence (the four four biopsies examined in the immunological study of cases were ascertained between 1995 and 2001). Despite this CMT1A mentioned previously (Gabriel et al., 2002). This drawback, an estimate of 1 in 250 compared with that for the difference may be methodological, re¯ecting possible prevalence of CIDP in the general population (1 in 100 000) reduced sensitivity of immunostaining in paraf®n compared still implies that the in¯ammatory process cannot be with frozen sections and the differing panels of antibodies explained by mere coincidence of CIDP and CMT disease. used for immunocytochemical staining in the two studies, or If anything, a value of 1 in 250 is probably an underestimate may simply be a consequence of sampling error. It is of the frequency of superimposed in¯ammation in CMT potentially relevant that biopsies from patients with chronic disease because of the method of case ascertainment. Only idiopathic axonal polyneuropathy (presumed to be non- patients for whom there was complete neuropathological in¯ammatory) were used as controls in the previous information, i.e. semithin sections and immunocytochemical Hereditary and in¯ammatory neuropathy 201 stains, were included. Thus, at least two cases from the series involving the gene product in CMT1A is unlikely to be of Thomas et al. (1997) (cases 44 and 46) were excluded relevant to in¯ammation in CMT1B or CMTX. through lack of histopathological data, though both had The development of an in¯ammatory process in CMT histories suggesting an in¯ammatory component. Another disease may relate to a disturbance of the normal function of two CMT patients with a history of stepwise deterioration and the protein encoded by the affected gene. Both PMP22 and positive sensory symptoms have been seen in the Royal Free MPZ are central to the formation of compact myelin (D'Urso Hospital peripheral nerve clinic since the end of the period of et al., 1990, 1999; Filbin et al., 1990). It has been suggested ascertainment (2001), but were not biopsied. that unstable myelin compaction in CMT1B could allow The pathogenetic mechanism by which in¯ammation `circulating immune elements access to normally sequestered occurs in the context of CMT disease is unknown. An initial endoneurial components' (Bird and Sladky, 1991; Watanabe question is whether the hereditary disorder always involves et al., 2002). A different mechanism would need to be Downloaded from https://academic.oup.com/brain/article/127/1/193/289222 by guest on 27 September 2021 an in¯ammatory component, which remains subclinical in the advanced for CMTX, in which the normal function of the majority of patients. As noted by others (Gabriel et al., 2002), GJB1 gene product, connexin-32, is as a gap junction protein, there are precedents for inherited neurological diseases believed to be involved in the control of molecular transport commonly being associated with in¯ammation. This applies in the paranodal regions of Schwann cells (Bruzzone et al., in the central nervous system, as in adrenoleucodystrophy 1996; Balice-Gordon et al., 1998). A potential unifying (Schaumburg et al., 1975), and peripherally, notably in hypothesis linking in¯ammation with and/or hereditary myopathies, such as facioscapulohumeral muscu- myelin dysfunction in the hereditary peripheral neuropathies lar dystrophy (Fitzsimons, 1994). In experimental studies of would be the putative capacity of Schwann cells to act as peripheral neuropathy, mice heterozygously de®cient in the antigen-presenting cells (Lilje, 2002). murine equivalent of the MPZ gene show less severe In conclusion, despite these uncertainties about the under- neurological disease if the animals are also immunode®cient lying immunological mechanism(s), there is accumulating (Schmid et al., 2000). In the case of human CMT disease, evidence for a superimposed in¯ammatory process in a subgroup of patients with CMT disease. The phenomenon is however, most patients are unresponsive to immunosuppres- not genotype-speci®c. It may contribute to the explanation of sant therapy (Prensky and Dodson, 1984) and histopatholo- the considerable phenotypic heterogeneity seen even within gical changes suggesting in¯ammation are present only in a families with the various genotypes (Thomas et al., 1997; minority of biopsies (Gabreels-Festen et al., 1993). Our own Donaghy et al., 2000; Gutierrez et al., 2000). Finally, the preliminary calculations, given above, indicate a relatively recognition of an in¯ammatory component creates thera- small proportion of CMT patients with coexistent in¯amma- peutic opportunities for some CMT patients, beyond the time- tion, albeit a much greater proportion than would be predicted honoured measures of physiotherapy, orthotics, orthopaedic simply by coincidence of CIDP and CMT disease. surgery and genetic counselling. An alternative view, therefore, would be that only a subgroup of CMT patients is predisposed to superimposed in¯ammation, presumably as a result of an additional genetic Acknowledgements susceptibility to immunological neuropathy. This subgroup is We wish to thank Drs Heather Angus-Leppan, Jeremy Gibbs envisaged as exhibiting an exaggerated immune response and Linda Parsons for permission to publish details of against myelin autoantigens exposed by the inherited patients under their care. We are also grateful to Jane neuropathy. For patients with the chromosome 17p11.2±12 Workman for technical assistance. All DNA analyses were duplication, it has been suggested that there may be genes carried out in the Neurogenetics Laboratory at the Institute of within the duplicated segment which are capable of modify- Neurology, Queen Square, London. ing the immune response (Gabriel et al., 2002). Such a mechanism could not apply, however, to patients who have coexistent in¯ammation in the context of point mutations in References the MPZ gene (Donaghy et al., 2000; Watanabe et al., 2002) Ad Hoc Subcommittee of the American Academy of Neurology AIDS Task Force. Research criteria for the diagnosis of chronic in¯ammatory or in the GJB1 gene, as described here. demyelinating polyneuropathy (CIDP). Neurology 1991; 41: 617±8. A pathogenetic role has been proposed for antibodies Balice-Gordon RJ, Bone LJ, Scherer SS. 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