Isolated proximal weakness of the legs due to neuroborreliosis

Abstract

Proximal muscle weakness of the legs is a symptom with a broad differential diagnosis. It is mainly caused by neuromuscular disorders and is often a diagnostic challenge. Here, we present a 73-year-old man with isolated proximal weakness of the legs due to lumbar root involvement on the basis of neuroborreliosis. After treatment with intravenous antibiotics he recovered completely. This is the first described case with isolated proximal muscle weakness of the legs due to neuroborreliosis. Despite the fact neuroborreliosis is a rare cause of proximal muscle weakness of the legs, clinicians should include it in their differential diagnosis, especially since it is a treatable condition.

Background

We present a well-known clinical vignette, proximal muscle weakness, with a rare, novel and well-treatable cause. Our case presented with isolated proximal muscle weakness of the legs, which is often a diagnostic challenge. There is a broad differential diagnosis that can be divided in (less common) central and peripheral causes, mostly neuromuscular disorders.¹ After the first negative ancillary investigations, new heteroanamnestic information and, subsequently, positive serology findings led to neuroborreliosis as the cause of his complaints. The lumbar nerve roots were involved as the site of causing weakness. To our knowledge, this is the first case with isolated proximal muscle weakness of the legs due to neuroborreliosis. Clinician should include it in their differential diagnosis, especially since it is a condition that can be treated without any residual complaints. You should not miss it, like we almost did.

Case presentation

A 73-year-old man developed progressive walking difficulties over the course of 4 days. Support of two people was necessary to cover short distances and to make transfers. Moreover, he had already fallen four times. Luckily, he was not injured seriously. The patient had only mild pain in his upper legs. He consulted the outpatient clinic because he would like to walk independently again. His medical history contained hypertension treated with chlorthalidone and conservatively and successfully treated right sided neurogenic claudication L5 due to a neuroforaminal stenosis. His family history was negative for neuromuscular diseases.

Neurological examination showed obvious symmetric proximal muscle weakness of the legs. Medical Research Council Scale for Muscle Strength (MRC) was used: iliopsoas MRC grade 2/2, hamstrings MRC grade 4/4, quadriceps MRC grade 4/4. The straight leg raising test (Lasegue) was negative on both sides, the revered straight leg raising test (revered Lasegue) was slightly positive on both sides. There was an obvious Gower’s sign. There was no distal weakness of the legs. The arms were unaffected: normal sensory and normal motor function. Except a minimal loss of vibration-sense at the feet, the sensory function of the legs was also unaffected. The biceps tendon reflexes were low, and the Achilles tendon reflexes were absent. The triceps tendon reflexes, patellar tendon reflexes and the plantar reflexes were normal.

We decided to make a summary of the clinical vignette, a differential diagnosis and a plan for relevant ancillary investigations. After the first investigations, we performed a new anamnesis and a more detailed hetero-anamnesis. In this conversation, his wife told us that the patient had multiple tick bites during the last years. These were all without any sign of erythema chronicum migrans.

Investigations

Blood results including C reactive protein, vitamin B₁₂, methylmalonic acid, Creatine Kinase, Thyroid Stimulating Hormone, Thyroxine (T4), sodium, potassium, magnesium, calcium, phosphate, Parathyroid hormone (PTH), vitamin-D, anti-Acetylcholine Receptor Antibodies, anti-Volgtage Gated Calcium Channel Antibodies and alfa-glucosidase were all normal.

Despite the absence of pyramidal signs, we ruled out a central neurological origin of the weakness. A CT-head and an MRI of the total vertebral column, including the lumbar column, were both normal.

Nerve conduction studies (Sensory: n. suralis and n. medianus; Motor: n. medinanus, n. ulnaris, n. tibialis and n. peroneus) showed, including F-waves and tibial H-reflexes, no abnormalities. Needle myography showed normal motor units in the musculus biceps and tibialis anterior on both sides. In the musculus quadriceps and the long head of the biceps femoris we found a neuropathic pattern on both sides, the musculus iliospsoas showed a single muscle action contraction pattern on both sides, also a neuropathic pattern. None of the muscles showed spontaneous electromyographic activity, fibrillations or positive waves.

Borrelia serology was performed after the new hetero-anamnesis. This showed positive IgM and IgG (Elisa and Western blot) serum values for Borreliosis. A subsequent lumbar puncture showed a mild pleiocytosis: 45×10⁶/L with 97.8% lymphocytes/monocytes, a glucose of 4.0 mmol/L (normal) and a total protein of 1.45 g/L (increased). IgM and IgG were positive for Borrelia in the CSF as well, with a positive index of 25.7 (increased, reference <2.0).

Differential diagnosis

At first, we made a summary of the clinical vignette to lead us to the differential diagnosis. In this case we noted: ‘Isolated symmetrical proximal weakness of the legs without sensory loss due’. The differential diagnosis of neuromuscular disorders can be made on the pattern of weakness:

1. Proximal versus distal weakness.

2. Symmetric versus asymmetric weakness.

3. sensory loss versus no sensory loss.

The differential diagnosis of isolated symmetrical proximal weakness of the legs without sensory loss includes metabolic disorders (electrolyte disturbances, vitamin deficiency especially vitamin B₁₂ and D, thyroid dysfunction, parathyroid dysfunction), central disorders (eg, cervical-cord stenosis/or myelopathy) or primary neuromuscular disorders (myopathy with increased Creatine Kinase, myopathy without increased Creatine Kinase, myasthenia gravis, Lambert Eaton myasthenic syndrome and Pompe’s disease). This is mostly based on the differential diagnosis of diseases with a limb-girdle muscle weakness (table 1). Blood results (electrolytes, vitamin B₁₂ and D, Thyroid Stimulating Hormone, Thyroxine (T4), Creatine Kinase, calcium, phosphate, Parathyroid hormone, anti-Acetylcholine Receptor Antibodies, anti-Volgtage Gated Calcium Channel Antibodies and α-glucosidase-activity), imaging (CT-head and MRI of the total vertebral column) in our presented case however were normal. The physical examination in combination with the EMG led us to lumbar root nerve involvement. Unfortunately, we did not have needle-EMG data of the lumbar paraspinal muscles. This could have given us the final anatomical site of pathology. Nevertheless, given the distribution of weakness and EMG findings we localised the symptoms in the lumbar nerve roots. At that point, without a diagnosis, one of the authors remembered the words of his former trainer in neurology: ‘If you don’t understand the case or you have no clear explanation for the medical condition start all over again with a new anamnesis, heteroanamnesis and neurological examination’. This brought us to the diagnosis neuroborreliosis based on his wife’s story about multiple tick bites.

Table 1.

Differential diagnosis limb girdle muscular weakness

Endocrine/metabolic	Cushing’s syndrome Hyperthyroidism Hypothyroidism Hyperparathyroidism Acromegaly
Anterior horn cell	Spinal muscular atrophy Kennedy’s disease
Radiculopathies	Hernia Nuclei Pulposi L3 and L4 both sides Infectious: for example, Neuroborreliosis (this case)
Neuropathies	Motor variants demyelinating neuropathies Motor variants Guillain-Barre syndrome Motor variants Chronic Inflammatory Demyelinating Neuropathies
Neuromuscular junction	Myasthenia Gravis Lambert-Eaton myasthenic syndrome Botulism
Myopathies	Hereditary Muscle dystrophies: Duchenne and Becker muscular dystrophy, Limb-girdle muscle dystrophies, Myotonic dystrophy type 2, Fascio-scapulohumeral muscle dystrophy Metabolic myopathies: Mitochonrdial myopathy, Pompe’s disease, Mc Ardle’s disease, ‘lipid-storage’ diseases Congenital myopathies Channelopathies Acquired Inflammatory myopathies: Dermatomyositis, overlap syndromes, inclusion body myositis Toxic myopathies

Treatment

Intravenous ceftriaxone (2 g/day) was started for 4 weeks.

Outcome and follow-up

The patient rehabilitated in a nursing home. After 2 months, he was completely cured and could walk normally again. Now, 3 years after onset, he is still in a good health without any difficulties in walking.

Discussion

Proximal muscle weakness in both arms and legs due to dermatomyositis in relation to Borrelia is a better-recognised clinical vignette^2–5 than our case with isolated proximal weakness of the legs due to neuroborreliosis. General criteria for dermatomyositis are proximal muscle weakness, increased muscle-associated enzyme (Creatine Kinase), characteristic rashes and typical EMG and histological features.⁶ These classical signs were absent in our patient, except for the proximal muscle weakness of the legs, so we called it isolated proximal weakness in the legs. In combination with a light pain in the upper legs, the positive revered straight leg raising test, EMG and the serology results, this presentation is most likely due to a multiple lumbar radiculopathy based on neuroborreliosis.

Concerning the case reports of lyme myositis with proximal weakness we can report the following: The first report of Lyme-myositis described a patient with severe myalgia in combination with proximal muscle weakness (arms and legs) and an increased Creatine Kinase.⁵ EMG in combination with histological features were compatible with myositis. Additional analysis in this case confirmed the involvement of Borrelia. The proximal weakness of both arms and legs improved after antibiotic treatment. Hoffmann et al, Horrowitz et al and Novitch et al described patients with typical symptoms of dermatomyositis due to Borrelia.^2–4 Gorson et al described five cases of an acute brachial diplegia due to Lyme borreliosis.⁷ Patients developed pain and proximal muscle weakness of the arms within 3 weeks of onset. All patients responded well to antibiotic treatment.

We presented the first case of neuroborreliosis with isolated proximal weakness of the legs without any signs of a (dermato)myositis. Only Siddiqui at al. also diagnosed a patient with neuroborreliosis with as a sole symptom proximal muscle weakness, however, this included proximal weakness in the arms and was accompanied by a Syndrome of inappropriate antidiuretic hormone secretion (SIADH). This proximal muscle weakness also improved clearly after antibiotic treatment.⁸

Patient’s perspective.

It was terrible to have weakness in my legs and being dependent for all activities. I was confused about the fact that they did not know the cause of my complaints. I was relieved by the diagnosis, and especially after the treatment and the result.

Learning points.

• Novel: We present the first case with isolated proximal weakness of the legs due to neuroborreliosis.

• Neuroborreliosis should be included in the differential diagnosis of isolated proximal weakness of the legs, especially when there is lumbar nerve root involvement.

• IMPORTANT: Despite it is a rare condition, it is very important because neuroborreliosis is a well treatable condition in which patients can cure without any residual complaints. You should not miss it, like we almost did.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).