Nikolaos Karandreas

Athens State University, Athens, Alabama, United States

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Publications (9)30.35 Total impact

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    ABSTRACT: OBJECTIVE: To investigate the underlying mechanisms of polyneuropathy induced by HIV infection or antiretroviral drugs. METHODS: We tested 100 HIV patients (59 with AIDS). Ninety-three patients received antiretroviral drugs. Forty-four were treated with neurotoxic compounds (ddI, ddC, d4T). Nerve conduction velocities and the sympathetic skin response (SSR) in palms and soles were measured in all patients. In skin biopsies (ankle and thigh), the intraepidermal nerve fiber density (IENFD) and the number of epidermal fibers without contact to the basal membrane (fragments) were quantified using PGP9.5 staining. RESULTS: Severity of the disease (CD4+count) correlated to conduction velocities of peroneal (p<0.01, Spearmans rank correlation), sural (p<0.01) and median nerves (p<0.05/p<0.001, sensory/motor). In contrast, the duration of neurotoxic treatment did not impair conduction velocities (p>0.3) but correlated to reduced IENFD in the ankle (r=-0.24, p<0.05). Despite their reduced IENFD, patients with long neurotoxic treatment had a high number of fragments irrespective of their CD4+count. CONCLUSIONS: Neurotoxic treatment appears to primarily impair thin fiber conduction, whereas HIV neuropathy is linked to large fiber impairment and reduction of fragments of nerve fibers. SIGNIFICANCE: These findings emphasize the differential pattern of polyneuropathy in HIV patients caused by the infection or induced by antiretroviral treatment.
    Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 07/2012; · 3.12 Impact Factor
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    Thomas Zambelis, Georgios Tsivgoulis, Nikolaos Karandreas
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    ABSTRACT: The investigation of the association between known risk factors and laterality in patients with carpal tunnel syndrome (CTS). Patients and 130 consecutive subjects with CTS only, or mainly, in the left hand were compared with 130 consecutive subjects with CTS only, or mainly, in the right hand. The following parameters were recorded: age, sex, job, handedness, hand mainly used in daily activities, BMI, diabetes mellitus, thyroid dysfunction, wrist trauma and connective tissue diseases. A left dominant hand was independently associated with 13-fold higher odds for left-hand CTS, while a right dominant hand had 5-fold higher odds for right-hand CTS. Right-hand CTS was more frequent in younger subjects and females. Older age, higher BMI and diabetes mellitus were more prevalent in patients with bilateral CTS. Age and BMI were independently associated with bilateral CTS.
    European Neurology 12/2009; 63(1):43-7. · 1.50 Impact Factor
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    ABSTRACT: Limb hypoplasia is a rare congenital disorder. Is usually encountered in patients with segmental spinal dysplasia (SSD), in progressive facial hemiatrophy (Parry-Romberg syndrome) and in other rare conditions. We performed an extensive electrophysiological study in a 18-year-old female with congenital left lower limb hypoplasia, but with no motor and sensory deficit. Electrophysiological investigation comprised motor and sensory nerve conduction velocities, needle EMG, quantitative sensory studies and SEP with standard techniques. The study showed markedly involved large diameter peripheral sensory nerve fibers and intact motor and small diameter peripheral sensory nerve fibers. Extensive electrophysiological investigation in cases of limb hypoplasia has not been previously performed. In this patient congentital hypoplasia of the muscles also involved the peripheral large diameter sensory nerve fibers.
    Neurological Sciences 07/2008; 29(3):177-9. · 1.41 Impact Factor
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    ABSTRACT: The study assessed HIV-related and anti-retroviral therapy-induced neuropathy in myelinated and unmyelinated nerve fibers. One hundred consecutive HIV patients were examined clinically and standard nerve conduction velocities were measured. In addition, electrically induced sympathetic skin response (SSR) was assessed in the palms and soles. The difference in delay of SSR in palms and soles (DeltaSSR) was calculated as an indirect measure of C-fiber conduction velocity. Thick fiber conduction velocities significantly decreased with age and increasing stage of the disease, whereas no effect of stage was found for DeltaSSR (p=0.6). In contrast, medication of at least one of the most known neurotoxic drugs zalcitabine, stavudine, or didanosine did not result in significantly lower conduction velocities in thick fibers (51.29+/-3.4 m/s vs. 50.86+/-3.5 m/s), but was related to an increased DeltaSSR. DeltaSSR allows an indirect measurement of C-fiber conduction velocity. In HIV this measure of unmyelinated sympathetic fibers was most sensitive to anti-viral treatment whereas conduction velocity of myelinated somatic fibers was more sensitive to disease-related neuropathy. The results suggest that HIV neuropathy preferably affects myelinated and anti-retroviral therapy unmyelinated fibers.
    Autonomic Neuroscience 11/2007; 136(1-2):90-5. · 1.85 Impact Factor
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    ABSTRACT: A simple score derived in the Oxfordshire Community Stroke Project (ABCD score) was able to identify individuals at high early risk of stroke after a transient ischemic attack (TIA) both in a population-based and a hospital-referred clinic cohort. We aimed to further validate the former score in a cohort of hospitalized TIA patients. We retrospectively reviewed the emergency room and hospital records of consecutive patients hospitalized in our neurological department with a definite TIA according to the World Health Organization (WHO) criteria during a 5-year period. The 6-point ABCD score (age [<60 years=0, > or =60 years=1]; blood pressure [systolic < or =140 mm Hg and diastolic < or =90 mm Hg=0, systolic >140 mm Hg and/or diastolic >90 mm Hg=1]; clinical features [unilateral weakness=2, speech disturbance without weakness=1, other symptom=0]; duration of symptoms [<10 minutes=0, 10 to 59 minutes=1, > or =60 minutes=2]) was used to stratify the 30-day stroke risk. The 30-day risk of stroke in the present case series (n=226) was 9.7% (95% CI, 5.8% to 13.6%). The ABCD score was highly predictive of 30-day risk of stroke (ABCD=0 to 2: 0%, ABCD=3: 3.5% [95% CI, 0% to 8.2%], ABCD=4: 7.6% [95% CI, 1.2% to 14.0%], ABCD=5: 21.3% [95% CI, 10.4% to 33.0%], ABCD=6: 31.3% [95% CI, 8.6% to 54.0%]; log-rank test=23.09; df=6; P=0.0008; P for linear trend across the ABCD score levels <0.00001). After adjustment for stroke risk factors, history of previous TIA, medication use before the index TIA, and secondary prevention treatment strategies, an ABCD score of 5 to 6 was independently (P<0.001) associated with an 8-fold greater 30-day risk of stroke (hazard ratio, 8.01; 95% CI, 3.21 to 19.98). Our findings validate the predictive value of the ABCD score in identifying hospitalized TIA patients with a high risk of early stroke and provide further evidence for its potential applicability in clinical practice.
    Stroke 01/2007; 37(12):2892-7. · 6.16 Impact Factor
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    ABSTRACT: It is well recognized that statins affect muscular tissue adversely and that their use is associated with clinically important myositis, rhabdomyolysis, mild elevation of serum creatine kinase (CK) levels, myalgias, muscle weakness, muscle cramps, and persistent myalgias or serum CK level elevations after statin treatment is discontinued. The association between statins and the disclosure of presymptomatic metabolic myopathy is another underrated phenomenon related to statin therapy that was recently recognized in rare cases. The purpose of this report is to provide additional support for this association and to report other neuromuscular disorders that have also been seen following statin intake. The present case series illustrates that statins may act as unmasking agents in asymptomatic patients with a latent neuromuscular disorder. Thus, it may be postulated that statin intake may be a sufficient insult to precipitate neuromuscular symptoms and substantially increase muscle enzymes in presymptomatic patients with an abnormal neuromuscular substrate. In conclusion, muscular symptoms or increased serum CK levels persisting after statin treatment discontinuation should alert the clinician to pursue further diagnostic evaluations for the detection of potential underlying neuromuscular diseases.
    Archives of Internal Medicine 08/2006; 166(14):1519-24. · 11.46 Impact Factor
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    ABSTRACT: Monoclonal IgM-related neuropathies constitute a heterogeneous group of disorders, which are generally poorly responsive to treatment. Rituximab, a chimeric monoclonal antibody against the CD20 molecule, has been used with success in patients with neuropathy and monoclonal IgM with anti-MAG or anti-GM1 ganglioside activity. Based on this observation, four patients were treated with IgM-related neuropathy with rituximab. Between January 1999 - December 2000, four patients with IgM-related neuropathy (one with chronic inflammatory demyelinating polyneuropathy (CIDP) and three with sensorimotor demyelinating neuropathy) were treated with rituximab. Rituximab was administered at a standard dose of 375 mg m(-2) iv weekly for a consecutive 4 weeks; 3 months later, four additional weekly courses were administered to patients who did not experience deterioration of their neuropathy symptoms. Neurological evaluation was performed before each rituximab infusion and at 1 week and 2 months after last infusion and every 6 months the following years; including motor (MRC in six muscle groups, 9-hole peg test, 10 m walk, hand grip strength), sensory neuropathy (vibration threshold and sensory subjective score) assessment. Neurophysiological parameters were also assessed (MNCV, SNCV, CMAP, SNAP). Strength improved in three of four patients; including the patient with CIDP. This patient developed a significant worsening of her weakness 3 weeks after the initiation of rituximab. This phenomenon coincided with a serum monoclonal IgM flare and resolved spontaneously 1 week later. Her improvement is ongoing for more than 5 years. Considering neurophysiological parameters, two patients showed a slight improved regarding conduction velocities and CMAP (10%) and the patient with IgM flare had a transient worsening of conduction velocities followed by improvement. In conclusion, rituximab is a safe and well-tolerated treatment which may be effective in some patients with IgM-related neuropathy.
    Leukemia and Lymphoma 06/2006; 47(5):859-64. · 2.61 Impact Factor
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    ABSTRACT: Peripheral nerve injury and brachial plexopathy are known, though rare complications of coronary artery surgery. The ulnar nerve is most frequently affected, whereas radial nerve lesions are much less common accounting for only 3% of such intraoperative injuries. Two 52- and 50-year-old men underwent coronary artery surgery. On the first postoperative day they both complained of wrist drop on the left. Neurological examination revealed a paresis of the wrist and finger extensor muscles (0/5), and the brachioradialis (4/5) with hypoaesthesia on the radial aspect of the dorsum of the left hand. Both biceps and triceps reflexes were normoactive, whereas the brachioradialis reflex was diminished on the left. Muscles innervated from the median and ulnar nerve, as well as all muscles above the elbow were unaffected. Electrophysiological studies were performed 3 weeks later, when muscle power of the affected muscles had already begun to improve. Nerve conduction studies and needle electromyography revealed a partial conduction block of the radial nerve along the spiral groove, motor axonal loss distal to the site of the lesion and moderate impairment in recruitment with fibrillation potentials in radial innervated muscles below the elbow and normal findings in triceps and deltoid. Electrophysiology data pointed towards a radial nerve injury in the spiral groove. We assume external compression as the causative factor. The only apparatus attached to the patients' left upper arm was the sternal retractor, used for dissection of the internal mammary artery. Both patients were overweight and lying on the operating table for a considerable time might have caused the compression of their left upper arm on the self retractor's supporting column which was fixed to the table rail 5 cm above the left elbow joint, in the site where the radial nerve is directly apposed to the humerus. Although very uncommon, external compression due to the use of a self retractor during coronary artery surgery can affect--especially in obese subjects--the radial nerve within the spiral groove leading to paresis and should therefore be included in the list of possible mechanisms of radial nerve injury.
    Journal of Brachial Plexus and Peripheral Nerve Injury 02/2006; 1:7.
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    ABSTRACT: Rickettsia conorii is endemic in the Mediterranean region. Infections are mostly benign and neurological involvement is unusual. We describe a case of a man who presented with acute facial nerve palsy followed by flaccid tetraparesis due to an electrophysiologically established polyneuritis with distal conduction failure. Elevated IgM antibody titres for R. conorii were documented by indirect immunofluorescent antibody test. After doxycycline therapy, the patient presented a rapid clinical improvement. Repeated electrophysiological examinations revealed significantly restored compound muscles, and sensory action potentials, corresponding to the clinical course after treatment and ex juvantibus, indicate the causative relation between R. conorii infection and the described clinical syndrome.
    Journal of the Neurological Sciences 08/2005; 234(1-2):113-6. · 2.24 Impact Factor