Mutations in GDAP1 are a frequent cause of AR CMT. They result in an early-onset, severe clinical phenotype. The range of nerve conduction velocities (NCV) is variable. Some patients have normal or near normal NCV, suggesting an axonal neuropathy, whereas others have severely slowed NCV compatible with demyelination. The peripheral nerve biopsy findings are equally variable and show features of demyelination and axonal degeneration.

Kinesthesia may be defective in patients with Parkinson's disease (PD), and this defect conceivably has a role in parkinsonian hypokinetic symptoms. In the present study, PD patients used kinesthetic perception to estimate the amplitude of passive angular displacements of the index finger about the metacarpophalangeal joint and to scale them as a percentage of a reference stimulus. The reference stimulus was either a standard kinesthetic stimulus preceding each test stimulus (task K) or a visual representation of the standard kinesthetic stimulus (task V). In task V, the PD patients' underestimation of the amplitudes of finger perturbations was significantly greater than that of normal subjects, but not for task K. PD patients' underestimation was also greater in task V than in task K; the difference between the underestimations was significantly greater than for normal subjects. These results suggest that, when kinesthesia is used to match a visual target, distances are perceived to be shorter by the PD patients. Assuming that visual perception is normal, kinesthesia is "reduced" in PD patients. This reduced kinesthesia, when combined with the well-known reduced motor output and probably reduced corollary discharges, implies that the sensorimotor apparatus is "set" smaller in PD patients than in normal subjects.

The end‐plate species of acetylcholinesterase (AChE) is an asymmetric enzyme consisting of a collagenic tail subunit composed of three collagenic strands (ColQ), each attached to a tetramer of the T isoform of the catalytic subunit (AChET) via a proline‐rich attachment domain. The principal function of the tail subunit is to anchor asymmetric AChE in the synaptic basal lamina. Human end‐plate AChE deficiency was recently shown to be caused by mutations in COLQ. We here report nine novel COLQ mutations in 7 patients with end‐plate AChE deficiency. We examine the effects of the mutations on the assembly of asymmetric AChE by coexpressing each genetically engineered COLQ mutant with ACHET in COS cells. We classify the newly recognized and previously reported COLQ mutations into four classes according to their position in ColQ and their effect on AChE expression. We find that missense mutations in the proline‐rich attachment domain abrogate attachment of catalytic subunits, that truncation mutations in the ColQ collagen domain prevent the assembly of asymmetric AChE, that hydrophobic missense residues in the C‐terminal domain prevent triple helical assembly of the ColQ collagen domain, and that other mutations in the C‐terminal region produce asymmetric species of AChE that are likely insertion incompetent. Ann Neurol 2000;47:162–170.

BackgroundAlthough controversial, paradoxical embolism via patent foramen ovale (PFO) may account for some of the migraine attacks in a subset of migraine with aura (MA) patients. Induction of MA attacks with air bubble injection during transcranial Doppler ultrasound in MA patients with PFO supports this view. It is likely that cerebral embolism in patients with right-to-left shunt induces bioelectrical abnormalities to initiate MA under some conditions.Methods and ResultsWe investigated changes in cerebral bioelectrical activity after intravenous microbubble injection in 10 MA patients with large PFO and right-to-left cardiac shunt. Eight PFO patients without migraine but with large right-to-left shunt and 12 MA patients without PFO served as controls. Four MA patients with PFO were reexamined with sham injections of saline without microbubbles. Bioelectrical activity was evaluated using spectral electroencephalography and, passage of microbubbles through cerebral arteries was monitored with transcranial Doppler ultrasound. Microbubble embolism caused significant electroencephalographic power increase in MA+PFO patients but not in control groups including the sham-injected MA+PFO patients. Headache developed in 2 MA with PFO patients after microbubble injection.ConclusionsThese findings demonstrate that air microembolism through large PFOs may cause cerebral bioelectrical disturbances and, occasionally, headache in MA patients, which may reflect an increased reactivity of their brain to transient subclinical hypoxia–ischemia, and suggest that paradoxical embolism is not a common cause of migraine but may induce headache in the presence of a large PFO and facilitating conditions.

The superficial peroneal nerve subserves sensation on the entire surface of the dorsum of the foot, except in small areas. All previously reported techniques for evaluating nerve conduction along this nerve tested a proximal portion of the nerve. We report a new method for evaluating sensory nerve conduction of the four branches of the distal superficial peroneal nerve. Two branches to the second and third toes of the medial dorsal cutaneous nerve and two branches to the fourth and fifth toes of the intermediate dorsal cutaneous nerve were studied orthodromically and antidromically in 37 feet of 21 normal volunteers using surface stimulating and recording electrodes and with a distance of 10 cm between the stimulating and recording electrodes. Maximum nerve conduction velocities (NCV) ranged from 41.8 to 46.9 m/s, and mean response amplitude ranged from 6.5 to 7.6 microV with the orthodromic technique. Values for NCV were almost identical when elicited by antidromic and orthodromic techniques, but response amplitudes were higher with the antidromic technique. Mean amplitudes of the distal superficial peroneal nerve were about 50% of the proximal superficial peroneal, and the conduction velocity in the distal superficial peroneal was slower than that in the proximal superficial peroneal nerve, by 8-14 m/s. In seven cases, distal superficial peroneal neuropathy was confirmed with this technique: two with proper digital neuropathy, two with medial dorsal cutaneous neuropathy, and three with intermediate dorsal cutaneous neuropathy.

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Magnetic resonance imaging findings of a 38-year-old man with epithelioid sarcoma of the penis is presented. It started as a firm, painless and slowly growing nodule at the base of his penis 6 months previously which caused pain radiating to the testis during coitus. It has been well known that sarcomas may well mimic reactive processes. Initial presentation of epithelioid sarcoma may provoke considerable diagnostic difficulty, and its differentiation from benign lesions, such as Peyronie's disease and chronic inflammation, may be a clinical problem. In our present report the MR findings are compared with those of the epithelioid sarcomas of various locations reported in the literature and differential diagnosis of the entity is discussed. To our knowledge, this is the first report regarding the MR findings of the epithelioid sarcoma of penis.